Shifting Dynamics

by JoMarsh

The heart of their issue was that they weren't just polar opposites but mirror images. Sometimes they brought out the best in each other, but most of the time they brought out the worst. A Dasey oneshot filled with angst, drama, and forbidden love.

AN: this is my ode to Dasey, as I've recently rediscovered this ship. Fair warning: it's dramatic, angsty, and not exactly the happy ending everyone wants.

If Dasey were to happen, this is my take on how it would happen. Also, I rewrote how Derek and Casey meet because I like my way better. I rewatched the series to write this, and I had forgotten about that how they met was included in the actual show. I like my way better, so bear with me.

If any Dasey fans still exist in 2022, this is for you!

---

It started innocently enough; Derek reflects. The first time he noticed her, he didn't know that she was going to be his new stepsister. Stepsisters were ugly and unimpressive, and she was surely the opposite of ugly and unimpressive. She was alone at the restaurant table, in her pink frilly top and blue jean skirt. She had her hair up, with a few loose strands framing her face. Her lips were frosted with lip gloss, and her smile was sweet.

He was fifteen, but he swore he'd never seen anything more perfect.

His dad and Edwin had to run back to the car as Edwin had forgotten something in the car, taking Marti with them – in true Derek fashion, he hadn't really been listening to what had been forgotten and went into the restaurant without them.

He had a few minutes, Derek figured, so he went to go chat her up. He didn't bother with some silly line, just went up and said hi. He did his best to make her laugh, and it sort of worked. Mostly she just smiled shyly at him. He smiled back, his stomach filling with nervous energy. This was different than how it was with other girls. There was an automatic jolt of electricity between them. It felt like they were instantly connected. He'd liked girls before, certainly, more than he'd admit to his friends, but this was something new and different. It felt like a promise, even before they had spoken any words to each other.

In another life, this would be a story she would tell their grandkids that he would scoff at but smile softly at the memory. It was sweet and innocent and filled with the promise of a connection neither had ever thought possible. It would be the start to a simple, if a little cliche, romance with the good girl falling for the bad boy, who actually wasn't that bad. It wasn't another life, however, and this life had something much more complicated in store for them.

A few minutes later, his dad, Edwin, and Marti slid up to the table, delighted that the two new step siblings were getting along.

Later, George would reflect on that particular moment and laugh at the irony. He hadn't noticed both Derek and Casey's smile vanish from their faces, of course. If he had, maybe he would have been able to do something, anything to stop the turmoil that was about to dominate both Derek and Casey's lives.

Nora and Lizzie joined a few minutes later from the bathroom - Lizzie had gotten her first ever period, and Nora had taken her to the bathroom to help sort everything out. George told Nora and Lizzie the good news - Derek and Casey were fast friends - and Nora smiled happily.

The tension didn't start until later, more specifically three days before the wedding. Derek made some offhand crack about love and romance being stupid, he couldn't even remember what he said exactly, but Casey had taken offense. Derek halfheartedly retorted. He didn't understand Casey yet, not even a little bit, so when she snapped back with rage at full force, he was taken off guard by her angry.

He hadn't learned that although Casey was sweet, loving and kind, she could also be pretentious, was often for of a romantic idealist than a realistic thinker – especially in regards to love, and was extremely set in her ways. This was the first of many fights, where Derek would learn that the sweet girl he felt an instant connection to, was also his equal in stubbornness and competitiveness. It only made him like her more.

Her anger persisted, though he hadn't really understood why. She glared at him, insulted him, and then took to simply ignoring him. He really hadn't meant to offend her, but her being unkind bothered him, even if he couldn't put his finger on why. He remembered that shy smile, though, so he was tempted to forgive her. It was his dad's wedding, so he figured he owed it to his dad to try to ignore it, in a very un-Derek-like selfless moment.

It wasn't until he saw Casey flirting with one of his dad's friend's sons, that he allowed himself to be angry. Then it was Casey's turn to learn that Derek was not afraid to fight dirty. That he'd fight her anger with a force so intense she oftentimes was left stunned. He was selfish, rude, and deceitful. He was used to getting his way without questions, and Casey proved to be the first real obstacle in his way. He could be ruthless when he wanted to be.

He wasn't jealous, of course. She was just impossible, filled with unrealistic ideals and romantic ideas. She was too sensitive, too girly to understand that he was just joking.

He repeated his new mantra, as he watched Casey and whatever-his-name-was, but her hand was on random guy's arm, and the jerk had definitely noticed Casey's sweet smile and pretty eyes. He was making her laugh, and it wasn't fair, because Derek wanted to be the guy to make her laugh.

He held on to his crush for a little longer, even despite his anger. He would have forgiven her, he begrudgingly admitted, if she just smiled at him again. It wasn't until the wedding day, when Nora and George had called a family meeting before they all started to get ready. The soon to be newlyweds started off by saying how happy they were to be merging their families. Yes, their lives were about to change, but they were gaining siblings. They were going to be incredibly happy together in their new life.

It hit him then, all the implications he'd been pointedly ignoring. She was going to be his sister.

Stepsister, he clarified. This would begin a series of reminders, both verbal and internal. Stepsister was different than sister sister. Sister sister would be disgusting because his thoughts and dreams were decidedly NOT brotherly. Stepsister was still wrong - at least as far as his daydreams went - but not sick and disturbed.

It was different, just not different enough.

They stood across the aisle from each other, as their parents declared their love for one and other, and Derek realized that he was royally screwed. She looked so pretty in her dress, and her smile lit up her face. They made eye contact as they stood across from each other and they both tuned out the priest's words. The crackle of the electricity flowed between them again, the butterflies and warm feelings flooding Derek's stomach once more.

She looked away first, looking embarrassed and with a slight redness twinging her cheeks.

He would have had a chance with her, he decided, if his dad hadn't married her mom. His heart sunk, as their parents said, "I do." He vowed to let it go, let her go, because he had to. His dad was finally happy, after being miserable forever, and loathe as he was to admit it, he liked Nora.

Derek could be really selfish, even he knew that, but he could never be that selfish. Not really.

So, he allowed a new dynamic to grow between them. He pushed and she pushed back. He went out of his way to annoy and upset her, shoving the guilt down as far as it would go, reveling in her flushed face (a little too much) and aggravated huffs. They fought, screaming and yelling each at other until they were hoarse. He purposely goaded her, and she constantly tried her hardest to outshine him.

It was a different dynamic than the nervous electricity that had surrounded them before. Derek hadn't anticipated that it would be just as alluring. He had hoped to build distance between them by creating a sturdy wall of tension. He did create tension, of that he was certain, but that tension had unintended consequences.

For two people who supposedly vehemently disliked each other so strongly, they spent a lot of time together. They frequently stood too close together. They found reasons to touch each other. She'd slap his arm during an argument - a little too hard, but he didn't really find it painful - and her hand would linger for a second too long. He'd poke her sides when they fought or find ways to instigate a physical fight, one where their bodies would end up pressed together, even if it was aggressively.

Derek found that he liked their arguments, and swallowed thoughts that he might actually be a masochist. She focused on him - and him alone - when they fought. The flush of her checks and the rise and fall of her chest (which always seemed to catch his eye) where delightful to look at. Her piercing gaze and the pure warlike aggression to her fighting style, even when she knew she was wrong, was endearing to him.

There were a lot of things wrong with him, he quickly realized. He knew this, yet he never was able to give his obsession with her up. He'd vow to let her go, but then she'd walk around in her sweats and little crop top that she called "work out gear" or smile a pretty smile, and he'd break that vow without a second thought. He was sure it would kill him one day, and he knew there would be hell to pay if their parents found out. But he'd swear to God that he couldn't imagine his life without her.

He fought dirty, of course, and was meaner than he needed to be, but she always had the upper hand. He couldn't give in just because her smile turned his insides to mush. He resented that they did – turn to mush, that is - at all, even if he kept coming back for more.

It was Lizzie, in the end, who convinced him to ease up on her. It was that horrid, awful word that convinced him. Sister. The worst word in the English dictionary. Except it wasn't, because he loved Marti more than anything, and Lizzie too. It was just Casey he struggled with.

He hated to admit it, but he loved her more than anything, too, but in a completely different manner.

He eased up with her, deciding to help her get over the term Klutzilla, even if he had been the one to give her the stupid nickname in the first place. When he realized that she had a crush on Sam (of all people, his best friend), it felt like the wind had been knocked out of him.

He left her room, and leaned against the door, the pain, jealousy, and absurdity of it all hitting him hard. He noticed Lizzie then, sitting on the stairs, and smiled at her, assuring her that he'd help Casey.

It was just breaking his heart to do so.

This started their new dynamic - it was ever changing. One where they had clear lines that couldn't ever be crossed. They could push and pull and antagonize, but there was a point that they could not cross. Of course, they'd cross that line a million times, but the other person would do something sweet and considerate, and all would be forgiven. They'd share a quiet smile or a nice moment, and then one of them would realize that this was dangerous territory, that they were edging towards a completely different line, one that once crossed could certainly NEVER be uncrossed. The fighting would start again, in a desperate attempt to get away from that line, edging them closer to the other, but that one was much, much safer. The cycle continued, again and again and again.

It was so tiring, yet Derek still thanked God for Casey because despite it all, he couldn't imagine life without her.

He'd still fantasize, in the dark quiet hours of the night, of course, about how their first meeting would have gone differently if they hadn't been stepsiblings.

They'd certainly be dating now if they weren't, and he'd know what her lip gloss tasted like, and perhaps he'd know other things, like the curve of her hip, the softness of her skin, or the swell of her breasts. Those thoughts were dangerous, though. They shared a wall, and the last thing he needed was her to hear him touch himself while imagining touching her.

It was different for her, of course. She had noticed him at the restaurant - he was cute, and somehow despite the fact that she wanted to straighten his messy hair (or was it run her hands through his hair), she found his smile enticing. His eyes were warm and all-consuming as he joked with her. She felt giddy and flushed as he talked to her. She was too nervous to laugh at his jokes, but she could keep the smile off her face.

It came to a shattering halt when the word stepbrother was introduced. His smile faded as quickly as hers, and she hated to see it go.

Casey was a good girl though, and followed the rules, and stepbrothers were certainly off limits. She avoided his gaze for the rest of dinner. Their first fight was forced, she pushed harder then she should and that had left him confused.

She purposely flirted with someone at one of their parents wedding events. His name was Todd, and Todd was certainly not funny, but Casey laughed anyways and wished she felt the butterflies in her stomach for Todd instead of Derek. She caught Derek glaring, and felt a pride swell in her chest because he was jealous. She shoved the thought away because it didn't matter if he was jealous or not.

Stepbrother. Stepbrother. Stepbrother.

When the fights began, she welcomed them. She allowed herself to be a little more dramatic than necessary and pushed herself to be more competitive than usual. We'll not really, but that made her feel better about herself, and thus began the series of lies she told herself. She quickly learned that the hardest lies to tell were the ones she told to herself.

Emily thinking Derek was hot was gross. She lied convincingly about that one, because the entire female population at her school being obsessed with Derek did make her sick, just not for the right reasons. She didn't lie, when she vehemently disagreed when Emily insisted that she was lucky to be Derek's stepsister. She absolutely did not feel lucky. The lies continued, some greater in magnitude, some smaller and simpler.

Derek did not look good in his leather jacket. Girls, especially her, did not like Derek better when he was sweaty. She definitely did not want to go to Derek's hockey games. Her heart did not thump in her chest when he said her name. She definitely did not feel the weight of his stare that one time she had to trek in her towel down the hallway because she had forgotten her robe (she did not make that mistake again, because the look on his face had been pure electricity and if she had to face it again, she'd surely cave to his will – whatever that may be).

This began her new ebb and flow, one that would consume her, she was sure, for the rest of her life. Because sometimes she really did hate Derek. He could really, really, be an asshole. He'd bring her to tears (not that she'd let him see it, of course). His insults hurt, and she wasn't made of steel.

It stopped mattering, after a while, how cute he was, or how his eyes made her melt inside. His words would cut deep and would keep her up at night. It didn't matter that their first meeting had the tinges of romance, because she'd surely never be with someone who constantly made her feel awful and insecure.

There were times that she really did hate Derek, that she gave up on the little silver of hope that kept her wanting Derek. Those times always were the darkest. He could always tell when their fighting shifted from competitive challenge to extreme dislike.

He'd do something sweet or kind, and she'd promise she wouldn't melt, but always did. He had a way of thawing out her hard edges. She wished that she had the same effect on him.

Something always pulled her back to Derek; something always made her forgive him. Their lack of fighting would be a reprieve, and their standstill will foster such charged moments, that they'd play on loop in her head for months. It was the way their eyes locked, during the truces, that kept her coming back for more. The air between them was alive, all the cells in her body demanding his touch.

It was an agonizingly wonderful. It wouldn't last long, ass they were both stubborn, and moreover, they were both completely self-centered in their own way. The push and pull of their arguments would start flirtatiously and then end in flames. Still, it would take months for the thrill of their truce to wear off, and though the never did anything romantic, the heat of the moment would make her toss and turn in her bed with need for something, but God, she couldn't figure out what.

She'd discover what, exactly, she wanted from him, when she not so accidently touched herself between her legs one night. She'd never done anything of the sort, but she thought of Derek and his lips the entire time. They didn't fight during her fantasies, but they were equally as passionate.

She pretended it hadn't happened the first time, but by the fifth and sixth time, she was too deep in it to care.

She'd tell her friends she thought of Sam when the topic came up during a sleepover. It was embarrassing, but not as embarrassing as touching herself to thoughts of her stepbrother.

Her crush on Sam was real, as real as the sweet relationship they created, even if it was fleeting. She loved (or at least really, really liked) Sam in a completely different way than she cared about Derek. That should have gone without saying, but her affections for Sam had a ticking clock, and her love for Derek may have waxed and waned, but she was certain it would remain as long as she did.

Derek became a part of her. He was her first and last thought every day, even when she was convinced she hated him and determined to never forgive him. They danced around each other their entire existence. She could set aside her feelings and form normal, healthy attachments to other boys, but those romances always fizzled, and Derek always, always remained.

Her counselor once told her, "If you give love, you get love" in reference to Derek. Surely, he wouldn't have said that, if he had any idea the love that both Derek and Casey craved from one and other. She thought of his words, late at night when her thoughts of Derek became extremely dangerous, when she panted and sighed at his imaginary touch. She thought of other implications of giving and getting love, and then was horrified at her dirty mind.

Because Paul had certainly not meant that.

And then he'd piss her off again, or worse, tear her down to a million Casey shaped pieces. She'd feel shame them, at how she thought of him while doing that. She'd go to hell for it. The shame would manifest itself in real sickness because what the fuck was actually wrong with her? She couldn't even get a crush right. Of course it would be Derek, who so completely off limits and so horribly cruel.

She learned to hate herself just as much as him. Her highs would tie in with her with adoration of him, but her lows were filled with self-hate, doubt, and absolute abhorrence for him. She was stupid and disgusting and he was a barbaric chauvinistic pig that she naively fell for.

She craved control more and more, the longer their standoff continued. She couldn't control her feelings, but she could control her actions. She would try and control his actions, but she'd been there before, and the results were always awful.

The worst part is she loved them all so much, in the right way: Edwin and Marti. Even George. It's just the Derek of it all that she could never get right. Their family is messy, loud, and annoying, but it's so, so perfect. They were the pieces her old life had been missing, so much so that she can't even stand to wish them away, even if it would absolve her of her sins.

Her need for control grew, with every passing day. She always assumed that teenage crushes eventually go away, but Derek's hold on her never seemed to dissolve. She kept waiting and waiting, but her strange, confusing, all-consuming attachment somehow became a part of her heart, etched in the corners, never heard, but always felt.

She learned to swallow the self-hatred, constantly reminding herself that she's in control. She put on such a good show that even she's convinced for a while, and branches out, dating Sam, Max, Truman, and Jesse. Their romances always felt off, but she shoved that aside. She learned, with Sam, not to seek Derek's approval of her boyfriends, because the look he sent her is so loaded, it sends her spiraling. He approved of Sam. He must because Sam is Derek's best friend, but the look he would send Casey is always so possessive: screaming mine, mine, mine. It's too hard to swallow and too fucking unfair, because Derek paraded his girl of the week around her every day. It's unfair because she can never be his, and it would really be kind if he could just try to pretend.

She learns quickly that the moments that are too close for comfort are usually instigated by Derek. Like the time they were locked in the bathroom, right before their parents busted them for their out of hand party, when he leaned his whole body towards her, their eyes locking. She was sure, if they had 30 more seconds alone together, he would have kissed her. Or the time that she got sick with a severe case of the flu, and he sat up all night at her bedside. She had been in and out of sleep, the fever causing delusions. But she knew the feel of his skin, the difference between her imagination and real life, so she knew that he held her hand the entire night and planted several kisses to her temple. He doesn't show the same consideration when she had appendicitis, so she assumed that maybe he learned his lesson the hard way.

It's almost always Casey that pulled away in those pivotal moments. Afterwards Derek would be viscous. It takes years to understand that he's just hurt and acting out. The whiplash kept her feelings at bay, however, and allowed her to hate him again, which is better as it's not as dangerous.

It just makes her incredibly sad, but she'd long sense learned to hide her tears; tears complicate things, and they make Derek sweet again. Sweet Derek always threatened her resolve.

---

The years passed as Casey and Derek danced around each other. Every time Casey thought she had Derek figured out, he'd do something to make her head spin. She'd never met anyone who challenged her quite like Derek. He was frustrating and infuriating, but he was also exciting and alluring.

They have sweet moments mixed in with the bad. It's little moments, here and there, but they matter. They matter more than either care to admit. It's a push and pull, a game they play where the rules are never set in stone.

One moment Derek is helping Casey lie to cover up missing an assignment - of which he gets a very perverse pleasure in corrupting her, though he can't really put his finger on why. The next moment, he's setting her alarm on Saturday, convincing her she's late to school.

After Casey helps him earn the A he needs by "grade grubbing," he buys here favorite coffee drink as a surprise. The surprised smile makes the whole mess worth it, and their drama softens for a while. It's not that he bought her coffee, it's the fact that he knew which coffee was her favorite that keeps her up at night.

In those first years it's typically Derek who is the instigator, not Casey. Casey responds dramatically and drastically, but she rarely starts the fights. By grade 12, she's just as guilty as he is in starting fights. Their fights are childish, reckless, and petty, but they still remain close, in their own way. Casey is always baffled by how Derek is simultaneously her least favorite and favorite person in the world. Derek marvels at how someone so completely annoying and infuriating can be the person he thinks about most.

When George and his band reunite, Casey and Derek sit on the table, apart from the family and exchange amused looks. When Lizzie starts one of her crusades or George and Nora fight or when Marti does something concerning, it's Casey that Derek looks to first and it's Derek that Casey seeks out to help solve the problem. They've built a relationship that is oxymoron in and of itself, even if Derek still doesn't know the definition of the word.

They date other people, of course.

Casey's relationship with Sam is dramatic and sweet but ends in a lifelong friendship.

Her relationship with Max is different. Max is exactly the guy that she's always dreamed of dating. He's sweet and kind; maybe he's not as gentlemanly as Casey always dreamed, but she understands (at least eventually) that her dreams are unrealistic. It's easy being with Max because he's the kind of guy that girls like Casey should fall for. She branches out and becomes a cheerleader and it's all perfectly perfect. Somewhere along the way, she loses herself in the difference of what should be and what actually is.

It's Derek that makes her realize (of course it is), when he makes a snide comment about how she's dropped all of her lame habits. Perhaps it was Derek being Derek or perhaps Derek's way of checking her. It doesn't really matter in the end. She starts to realize that maybe Max isn't as sweet as she originally thought. He's nice enough, sure, but somehow, he's helped (or was it pushed or manipulated) her to change into a completely different person with very little thought, as if she was clay for his to mold into the perfect girlfriend. Soon enough, she finds herself single, though she doesn't fully understand why. She was happy with Max, but happy and simple aren't really her anymore. Maybe it's never really been. Simple and easy are boring, and she learns that prefers a challenge.

Truman really is an imitation Derek. It's exactly how she imagined her and Derek meeting, in another life. It's dramatic and intense. He's smug and egotistical, with just a hint at sweetness. The attraction is a little forced because Truman isn't her first option, but it works. When he kisses Vicky it's a reality slap. In her fantasies Derek would never have cheated on her.

She loses her virginity to Truman, two weeks after graduation. He's completely sweet about the whole thing, and truth be told, it's her idea, mostly to get it out of the way before college. He's gentle and kind, and as far as first times go, it's about as good as it gets, she supposed. She comes home sobbing, sneaking in past curfew. It's Derek who finds her, and she can't tell him why she's crying; even she's not certain. He doesn't say anything about her tears, even though he's sufficiently freaked out. Just holds her as she cries and wakes up Lizzie, who spends the night in Casey's bed, confused but supportive. It's all wrong, all of it, but she can't tell Derek or Lizzie why.

She breaks up with Truman a week later. He's confused and hurt, but it doesn't matter. She can't shake the feeling that she's tossed something important away for all the wrong reasons. She wonders if subconsciously she slept with Truman because she couldn't sleep with Derek or if it had anything to do with Emily telling her that Derek wasn't a virgin.

Derek dates way more often and way less seriously than Casey. His first serious relationship with Kendra isn't really that serious, but he does loose his virginity to her on the sagging couch in their living room. Their relationship ends as quickly as it starts; they're far too similar and far too immature. Derek still thinks very highly of Kendra, even if he sees how silly they were.

When Amy breaks up with him because of his obsession with Casey, Derek's world is blown apart. She doesn't realize how deep the obsession goes, but it's too close to home.

Sally is a different story. It's the first (and only) time that he can imagine a life without Casey. Sally isn't an imitation Casey, though they do share similarities. He chalks that up to having a type and doesn't delve too deeply down that well. Sally is sweet and kind, bringing the best out of Derek. When she leaves for university, his heart breaks and its different than the constant Casey heartbreak. For just a little while, he convinced himself that there could a life of happiness without Casey, and his relationship actually doesn't center around her like all of his other relationships. Sally and Derek talk for a little while, but they both know that they won't work with all that distance and space.

He dates Emily for a while, but it's not really serious. He cares a great deal about Emily, but their relationship is forced, even if it is comfortable. He needed a date for prom, and dating Emily seemed like the logical answer to the problem at hand. It's fun, and they remain friends even after they break up a few weeks after graduation. It conveniently corresponds with Casey's break up with Truman.

Despite their various significant others, Derek and Casey were the primary relationship in each other's lives that all other relationships were second to. It's why Derek quit Smelly Nelly's and why he confronted Truman for cheating on Casey. It's why Casey spent so much time obsessing over Derek when he decided to drop out of school to follow Sally, and why she always bent her personal and ethical rules when it came to Derek.

While Casey was kind, thoughtful and smart, the truth was Casey was also arrogant, spoiled, and self-absorbed. Derek could be sweet, perceptive, and was a natural born leader, but he was also lazy, entitled, selfish, and oftentimes unkind. They'd grow out and into their worst habits as time passed, but the heart of their issue was that they weren't just polar opposites but mirror images. Sometimes they brought out the best in each other, but most of the time they brought out the worst.

Casey spent a lot of time fantasizing about if they met in an alternate universe. They wouldn't get along at first, that much she was certain of. It'd be a slow burn, she decided. Their relationship couldn't automatically be romantic, or they'd fizzle out for sure (or kill each other). They'd be older. Derek's hard edges would have rounded, and Casey's rigid ideals would have softened as they both naturally matured. They'd still fight all the time, but it'd be half the fun. She never could picture farther than that. Every time she did, she'd see a relationship in ruins. Even in her fantasies, Casey didn't see a future where they could coexist happily.

---

Things get more complicated when they go off to university. At first, they ignore each other, and while both had agreed to this plan, it's secretly agony for both of them.

They see each other at a party, and it's Casey who breaks first, while Derek smirks with glee.

"What is a keener like you doing at a college party? There's underage drinking, drugs, and premarital sex happening here, Case. You sure you can handle it?" He's teasing and not mocking, and Casey knows the difference by heart.

"I have a drink." She showed him the half empty cup with what he presumed was jungle juice proudly. "I won't do the drugs, but it's a party, so it's not my problem." There was a pause and she smiled evilly. "And I never said that I was against premarital sex."

He pushes away the jealously because even though he needs to know, knowing would kill him. So, he pushes the jealously down, and saves it for another day, because in another context her words could be considered flirtatious.

"Huh." He said, stalling. This is new. This territory feels exciting, but if he pushes too hard, she'll disappear again and that'll break his heart. "Well then, miss college girl, I think you need a shot."

She smiles hesitantly but eventually complies, a shy smile on her face that is so reminiscent of when they first met, that he almost kisses her right then and there.

His friends don't know who she is to him, so they smile encouraging, leering smiles at him. He smacks Tyler in the back of the head, telling him not to be a dick. He friends start to wonder who exactly she is, and Casey picks up on this.

"My name is Casey." She smiles sweetly at his four friends.

Derek points at his friends with a tight glare, begging them to fuck off. He hasn't seen her in over a month, so as far as he's concerned, they can go away. "Brett. Eric. Tyler."

She smiles at them and begins to engage in small talk. Derek sighs and pours five shots of vodka for all of them. Her eyes turn to him then, suddenly unsure. A few of her friends magically appear at her side.

"Kay-seee," one girl whines, clearly already drunk. Derek later finds out her name is Haley. "You can't do a shot without me."

Eric beams at the Haley, in her miniskirt and halter top, with her eyes glazed with drink and her pretty smile. "Of course," and pours three more shots for Casey's friends.

Casey stands a little too close to Derek during her shot, and he watches her. She gags a little and he discreetly rubs her back.

"I should have warned you," he mummers, softly.

"It's okay," she chokes out, blinking roughly.

They spend the rest of the night talking. Derek and Casey's friends - Haley, Natalie, and Sarah - hang out in a corner together, playing drinking games, dancing, and laughing. Derek and Casey remain in their own world, their friends casting glances and smirks their way.

It's a little after one in the morning when the mood starts to shift. Haley, who had been slurring earlier in the night, is now on the verge of throwing up. Casey throws Derek an apologetic look, and she and her three friends rush to the bathroom and then back to their dorm.

"Damn," Eric says, bumping his shoulder, as Derek deflates. "It's too bad. She seemed to really like you."

Derek shrugs because what exactly is supposed to say? The truth is much too twisted.

"You couldda scored, man." Tyler, who is also slurring, laments. "She was hot, too."

Derek slaps the back of his head, and his two other friends laugh.

"Did you know her, before tonight?" Brett asks. Brett's quickly becoming his best friend, and Derek realizes that Brett's question is loaded with implications.

"Yeah, we went to high school together." He ruffled his hair. It's not a lie. It isn't; they did go to high school together. "Never got along well, though."

Brett smirks at him. "You sure were getting along tonight, eh?"

---

He sees her, not even a week later, when he gets frantic call from her.

It's high strung Casey on the phone, a completely panicked princess. "Der-rek!" She yells. "It broke. Oh god, it broke. I don't know what I'm going to do. You have to get over here now!"

She stressed the word now aggressively, and he's tempted to fall back into his old ways and mock her, but something in her panicky tone makes him stifle that urge. Or maybe it's the memory of her swaying in front of him to the beat of the music at the party last week. She wasn't dancing with him, of course, but she was only a few inches from hips.

He realizes she won't sway in front of him any time soon if he continues to piss her off.

He shows up, completely unprepared with the mess he walks in to.

Casey and Haley, her drunken friend from the party and apparently also her roommate, have tried to bunk their beds without help.

They had, indeed, broken the bed. Haley was in tears and just kept saying her dad was going to be pissed.

Casey looked at him, wide eyes, unsure of how to deal with Haley's fear of her dad. It wasn't something either of them understood. Yeah, their parents had certainly gotten angry with them, but they never inspired this much actual fear.

"It's okay." Derek said calmly, even though he had absolutely no idea what he was going to do. "I'll fix it."

He ended up calling Brett, who did know how to fix the problem. He hadn't given Brett many details, just that he needed his help, but he wasn't terribly surprised when Casey opened the door. Brett smirked at Derek as Casey thanked him profusely.

The girls took Derek and Brett out for dinner afterwards, just to the local pub, and Derek wondered vaguely how Casey could afford to pay her half of the bill. She'd had always been better with her money, after all, so he didn't question it too much.

He found out later that she used the credit card their parents had given to her for emergencies (not to him, for obvious reasons). She told her mom the story, and George had called him, proud of his son for being there for his sister. Casey didn't get in trouble, of course, because it was Casey, but Derek found that it didn't bother him.

Because they had fun, the four of them. Well, the three of them. Derek would never like Haley, and vice versa. There was something off about the girl, and when Haley would later sleep with Daniel, the boy that Casey would date for a few months toward the end of her freshman year, Derek would have to push down the desire to tell her he told her so.

But Brett and Casey got along, and it was different then how Casey and Sam had gotten along. There was no flirtatious vibe or small smiles. Brett liked Casey, sure, but she was very clearly Derek's girl or whatever weird approximation of that they were playing at, so they joked and laughed like old friends and never, ever anything more.

They don't cross the line, just created more definitions for the line, pushing it farther and farther away. Being friendly isn't crossing the line. Having the same friends isn't crossing the line, this is sort of familiar territory anyways. Studying together isn't crossing a line, but it does typically start a fight, as Derek would much rather do anything but study, and Casey is still Casey. They eat dinner together most nights, typically accompanied by friends. He doesn't like Haley, but he finds Natalie and Sarah enjoyable to be around.

They don't date each other's friends, like in high school. Their friends don't know about their family, and even though Casey and Derek aren't dating, there is definitely a line in the sand. None of their friends would cross it, except maybe Haley, but she doesn't like Derek that much, so the point is moot. Their friends cast knowing smirks at each other when they fight or flirt, but none of them pushes them towards a relationship.

It's clear to everyone that they are on a path to dating, but that it has to happen in its own time. Casey freaks out the few times her friends tried to mention it, and it clearly becomes off-limits territory. Derek shrugs and tells Brett that he wasn't nice to her in high school, and that there's too much baggage there. He likes being something to her, and it's better than nothing. It so close to the truth, and Brett can tell Derek is being sincere, so he drops it.

Sam comes to visit. Derek tried to postpone it, but he misses his best friend. Casey hugs Sam and tells him she's missed him. Derek's heart throbs because he's not sure he'll ever recover from the heart break of them dating, even if their romantic feelings have long since dissipated.

Sam doesn't question their new dynamics and their friend groups being intertwined. At first, he thinks it's nice, that they're finally getting along. Casey and Derek keep a distance between them that is definitely not normal, and their friends notice immediately.

The girls question Sam, when Casey is not around, and find out they dated. Sam swears that it's platonic now, and that he came to visit both Derek and Casey, but they can tell something is off. Sam can tell too and asks questions of his own.

In the end, Sam isn't surprised, not really. Upon reflection, not even at all. Their words revolved around each other for three whole years. He'd never thought it before, because they shared parents and a bathroom, but it made sense. Sam swallows the bitter resentment he initially feels, because this knowledge somehow taints Casey and Sam's innocent relationship. Had she always felt something for Derek? Even when he told her that he loved her? Had Derek felt it when he had tried (successfully) to break them up? Breaking up with Casey had been his first heart break, and the knowledge that something that was decidedly not sibling-y existed between them made him indescribably sad.

He got over it quickly, because he really was over Casey, and he liked being her friend. Their relationship still feels different now, all three of them, and Sam doesn't visit for a while after he leaves. His calls and texts slow. Both Derek and Casey feel shame, though neither admits it to the other. Neither admits that anything has changed.

It takes about a month, but Sam begins texting and calling Derek and Casey again, and the tension fades. He won't visit again until the next year, but Derek visits him, and everything falls back into place.

Sam doesn't ask and Derek doesn't tell. There's not much to tell, besides. Mostly Derek and Casey are just friends, with a hint of sexual tension and a knack for being just a little too close, which really is nothing new.

They don't cross the line because it's been their constant companion for years, and they aren't sure what they'd do without it.

Casey starts dating Daniel during their second semester. Daniel is different than the other boys that Casey's dated. He's incredibly smart, good looking, and polite.

Casey's friends like him, but they still smile at Derek apologetically. Derek's friends try to dislike Daniel, but they're Casey's friends too, and Daniel is a hard person to dislike. Brett holds out the longest, because Brett truly is Derek's best friend, but eventually he caves, too.

It happens after Casey and Brett have a heart to heart, which Derek definitely, 100% did not mean to overhear. Casey and Brett are good friends, not as close as Derek and Brett, but the bond is real. So when Casey cried and tells Brett that her and Derek cannot happen, and that she really, really likes Daniel, he starts to thaw around Daniel. Brett is never really satisfied with the why of it all, he can't see the reason Derek and Casey can't be together, but they both feel it so strongly, that he just lets it go.

Derek ends up liking him, too, although it's definitely begrudgingly. He tells Daniel that if Casey gets hurt, it's Derek that he'll answer to. Derek isn't as scrawny as he was in high school, the hockey regimen filling him out, and he's always been able to sound truly menacing. Daniel gulps, but promises he really cares about Casey.

They form a friendship and even hang out. It makes Casey queasy, but she recognizes it's for the best because the other alternative is to let go of Derek, and that she absolutely could not do.

Casey is smitten, completely content with Daniel. She doesn't think of Derek when she's with him, and that's the best part. Despite what she knows she may always feel for Derek, her relationship with Daniel is real.

When Derek catches Haley flirting with Daniel, he corners her. Up until this point, their interactions had been civil, but Derek can be cruel, and he chews Haley up with his viscous words. Derek isn't too a worried, because Daniel is too nice to cheat, too good of a guy. In retrospect, Haley probably wouldn't have done anything with Daniel, but Derek got to her.

It wasn't fair that Casey got Daniel and Derek, and Haley got nothing but cruel words. Casey didn't notice at first, but Haley began to actively seduce Daniel. She picked up on it after a while, and an uncomfortable tension became to take shape. Daniel ignored it, mostly, and avoided Haley.

It wasn't until Daniel and Casey got into a huge fight, that it happened. The fight was over Derek, or at least sort of. Daniel wanted to meet Casey's family, but she obviously couldn't allow that. Daniel got too close to the truth, although in reality he was nowhere near it. When he accused her of having feelings for Derek out of the blue (because their fight had gotten that out of hand and c'mon, it was kind of obvious), she stuttered poor excuses.

They probably would have broken up over the fight, truly, but Daniel slept with Haley before they had gotten there. Haley purred with victory and couldn't wait to tell Casey.

It was just like what happen with Truman, although much much worse. Casey ploughed into Derek and Brett's room and rushed into a confused Brett's arms. She couldn't go to Derek's, at least not right away, because that'd make her the hypocrite and she currently had the moral high ground.

Derek beat the shit out of Daniel, like he promised he would. Brett had to intervene, otherwise Derek would have gone too far. In the end, Derek was lucky that Daniel didn't press charges, or he surely would have ruined his life.

Casey avoided her dorm room and Haley, although Haley tried to apologize for over a month. She slept on Derek and Brett's futon. Their dorm was always clean after that, and she brought them treats and sweets. She didn't try to make their dorm girly, like she had with their bathroom back home. She recognized that she was the outsider and tried to be respectful of their space; they tried to make her feel at home. Derek bought a few fluffy pillows and duvet cover for the futon - in dark blue, he couldn't force himself to buy pink - so she could be more comfortable. In return she helped (rewrote) a few of his papers, helping him retain the GPA he needed to retain his hockey scholarship.

Casey didn't really date much after the Daniel fiasco.

Their parents didn't visit a lot. Derek and Casey go home to see their family, claiming it's easier. It really is, so their parents don't push it, too afraid to dislodge the friendship formed between their two oldest children.

Their relationship reverts, slightly, when they enter their childhood home. They still tease instead of mock, but there is a harder edge around it, hiding the flirtatious undertones. They find it's easier to focus on their siblings than each other.

The family breaths a sigh of relief when they don't automatically break out in a nasty fight or throw food at each other during dinner. Casey focuses on Lizzie and Marti. Lizzie had a new boyfriend, and Edwin claims he has a "file" on him, but is really just a pro con list, outlining Matt's (because that's his name) faults and strengths. Lizzie is massively annoyed, but also touched by the gesture. Casey meets him, and hates him immediately, but doesn't tell Lizzie, because she knows Lizzie has to make sense of it all in her own time.

Marti is too smart for her on good and gets picked on in school. Casey comforts her, and Derek threatens to beat up her bullies. Casey stiffens at that, and Derek sighs helplessly. Casey tries her best to help Marti, but despite Derek's teasing, she hadn't been bullied in high school.

Derek and Casey worry about her constantly.

Edwin has grown into himself, with Derek being away. He still worships his older brother, but he accepts himself for who is, and for how different he really is from Derek. Casey tells Edwin she's proud of him and gives him advice about girls. Derek gives him different advice, and Edwin follows Derek's advice, because Derek never had any problems landing a girlfriend.

Sam visits them at home, too, and observes the dynamic they have there, how it different from when they away at school. He takes Casey out for coffee when he hears about Daniel, and comforts her in a way that only Sam could.

Emily doesn't visit much or answer Casey's calls and texts as often as she used to. When they see each other, they fall back into their friendship easily, but it's completely changed somehow, and doesn't last the second they part. This makes Casey indescribably sad, but it's life and a part of growing up. Eventually the calls and texts stop completely, and they're only friends when forced to be so, in front of their families.

But Sarah and Natalie are the best girlfriends Casey could have ever had, so she lets it go, because honestly the wall is too thick and the bridge too broken to fix their relationship. Upon reflection, Casey realizes she was the one to push Emily out, because she couldn't share the new life she had built with Derek with Emily. How could she? It's the first list of casualties in a long line of broken friendships, and damn, does it hurt the most. She's glad she still has Sam, at least.

Brett, Eric, and Tyler are amazing friends, too - especially Brett, who she is certain will remain one of her best friends for the rest of her life. Derek and Casey don't compete over Brett, like they would have in the past. Their relationships with him are completely different, but coexist so easily that it's natural.

When Derek and Casey go back home for the summer, their relationship is tested because it's one thing to pretend for a weekend, but several months is just too hard.

They avoid each other mostly, because Derek knows if he's cruel now, it'll crack their relationship, and Casey knows where pushing Derek will lead.

They both get summer jobs, and they alternate their time with Sam. He notices but doesn't say anything because, honestly what the fuck could he say? It's too bizarre, and they both determined to ignore it.

Casey focuses on Lizzie, as she's sure Lizzie is the person she loves most in the world, and watches as Lizzie turns in to a teenager. It's easier for Lizzie than Casey, but perhaps it's because Casey is a difficult person, and Lizzie is easy going and sweet.

The summer goes by quickly, and although her relationship with Derek is infinitely more complicated at home, she's missed the chaos. It's definitely bittersweet when Derek and Casey begin to pack their things, and she feels extraordinary guilty because she feels relief that she's going back to school. She misses Derek, the university Derek, who she's doesn't have to tiptoe around.

Their parents think they're maturing, learning to pick their battles. They'd surely wouldn't find them mature if they knew the strange web of lies they'd built at school.

They convince their parents they don't need help moving into their new apartments - Casey in a three bedroom with Sarah and Natalie and Derek in a four bedroom with Brett, Tyler, and Eric. Their lives are so hectic with Lizzie's sports, Edwin's friends, and Marti's drama, so they allow it.

They both sigh in relief. Because the life they built would surely crumble, if their friends met their parents.

They live in the same building. Casey's apartment is one floor above theirs, but honestly, the seven friends come and go in each other's apartments as they please.

The trouble begins when Derek gets a girlfriend. Alyssa is gorgeous - brown hair, blue eyes, and super outspoken. Brett sighs, thinking that Derek has a type. At least Casey wasn't that obvious when dating Daniel.

It starts off amicable enough, with Casey and Alyssa being courteous to each other. Natalie and Sarah aren't as friendly, but Casey sends them a glare and they all get a little nicer. Derek thinks this might actually work for a week or so.

It's not until a lazy Saturday morning, when Casey lets herself in to the guy's apartment to grab a few eggs (one of the things they actually regularly have stocked) for pancakes, and Alyssa comes out of Derek's room wearing pajamas, having obviously spent the night. Casey freezes, but quickly puts on a fake smile.

Derek exits the room, too, grinning, but recognizes Casey's cool, fake smile from their years of fighting, and his smile falls from his face. She apologizes for barging in, and Brett laughs at the absurdity of that statement, reminder her she's always welcome.

But Casey doesn't feel welcome anymore, because she's intruding on something, and her heart twinges because it should have been her. It couldn't be though. She doesn't say anything; she has no right, and Alyssa is nice.

Casey doesn't pop by unannounced anymore. She barely comes over. She still sees the guys, as they're a constant presence at her apartment (the girls are much, much better cooks).

Brett doesn't really like Alyssa, even if she is nice enough. Alyssa and Derek feel like a poor imitation of Derek and Casey. When Brett, Derek, and Alyssa are together, they don't mesh the same way. Brett ends up feeling like an outside, a third wheel.

He spends a lot of time at Casey's apartment when Alyssa is at his.

There's no real beef between the two girls, and they're always nice to each other, but it's uncomfortable when they're in the same room because they're so similar but so different. Their views are completely different, but their reactions are the same, and they're both so determined to not dislike each other.

It's awful to be around.

Their friends think that Derek and Alyssa aren't good together. They don't bicker or tease each other, and their vibe is all wrong. It would be easier to swallow, if Derek still didn't watch Casey when she moved, if he didn't reserve a special half-smirk-half-smile specifically for her. If he didn't wonder aloud, in front of Alyssa no less, where Casey was.

It doesn't last long between Derek and Alyssa, and no one is surprised. Derek's is only phased for a few days, and even admits to Brett that the whole relationship revolved around Casey.

It's different than Casey and Daniel, because Derek would sometimes forget that he was with Alyssa and pretend it was Casey. Brett tells him he's a dick, and Derek definitely agrees. He apologizes to Alyssa, but she won't hear it and slams the door in his face.

He resolves to not date for a while, at least not until he can get Casey out of his head. He resigns himself to being a monk for the rest of his life.

Casey doesn't forgive him either, though she'd never admit she was angry out loud. She still doesn't come over unannounced. She only comes over when they're all hanging out there. She no longer proofreads Derek's essays before he turns them in, and only eats dinner with him when someone else is there.

She doesn't hate him, like she would have in high school. She's completely at ease with him, as long as they aren't alone. She avoids it at all costs.

Alyssa was a reality check. Casey couldn't be the one leaving Derek's room after spending the night with him, in his bed. Derek doesn't really understand, but even though they're still on friendly terms, he feels an icy breeze from her.

Casey starts to hang out with other friends, missing their friend dinners and is noticeably absent when they all hang out. Natalie made excuses for Casey, while Sarah scoffed. They both knew it was Casey putting distance between her and Derek, but they couldn't understand why.

Then Emily called. It catches Casey off guard, but Emily was sobbing uncontrollably. Casey spent the entire night talking to her, wasting all of cell phone minutes. Casey wasn't super surprised when Emily showed up on her doorstep, but it did complicate things.

Emily stayed in Casey's room, and the discord between the two is all but forgotten. Emily was surprised when Derek walked right into Casey's apartment, and then room, but quickly learned that they had become friends.

Casey had put enough distance between herself and Derek, that Emily wasn't too suspicious, but she couldn't help her eyebrow raise when Casey informed her that she didn't want their friends to know that they were stepsiblings.

Emily didn't talk about why she came, and Casey didn't push, but a few days turned in to a few weeks. Eventually Derek and Casey determined that they had to talk with her.

They schemed together, and it felt like old times. They're friends encouraged it, distracting Emily because their new dynamic was weird and unsettling, worse than the undertones of sexual attraction and whatever was stopping them from dating. Derek prolonged the process because he was selfish. He missed Casey and hated the distance she had put between them. He hadn't pushed her, hadn't pushed them, so he didn't understand why she was backing off. He'd shake off the never-ending desire for her, if she'd simply be his friend again (at least in theory).

Their determination to help Emily proved to do just that, and the two confronted their friend. Emily still didn't want to talk about it, but she had definitely dropped out the of university, and it was becoming clear that something bad had happened to Emily. She was depressed and moody, two qualities that were very unlike Emily. Casey began to seriously worry, and although she never said the word (rape), she began to put the pieces together. Her heart broke for Emily, and Casey remembered how to hate herself. How could she push Emily away and leave her to her own defenses? What was it all for? Her insides squirmed uncomfortably because, really, what was it for? A pretend life, one where she wasn't even dating Derek.

She shuddered at the thought because even though she knew that's what she ultimately wanted; it was still programmed in her brain as wrong, wrong, wrong.

"Derek," she began slowly when she finally confronted him. "I think we should take Emily home. The Davis' don't even know she dropped out."

He sighed. "I know, but I'm not sure how to get her to go home. And we can't bring the Davis' here, because..."

He trailed off because how the hell did he put that in to words?

"We have to do something, Derek." Casey looked close to tears. "I can't help her, and she needs help."

He nodded, feeling helpless.

It's Derek, in the end, that convinced Emily to go home, although Casey isn't sure how. Her parents are exactly as they should be, kind and understanding. Casey and Derek visit more on the weekends, and so does Sam. Emily tells them that they're stupid, but appreciates it all the same.

The whole thing changes Casey and makes her blood run cold. Derek feels awful for Emily but doesn't really understand. Casey learns to check over her shoulder when she's waking alone, and when they're out drinking, she sticks by her male friend's sides. Tyler and Eric make fun of her sometimes, but they always stop laughing when Derek turns his glare at them.

The whole thing leaves Casey feeling empty. She thinks back on it more often than she should, and she feels like she's lost a part of herself. She feels guilty because it wasn't her trauma, and perhaps she doesn't have any right to feel this way. But Emily is her oldest friend, and it still eats away at her. She wonders if this is what it's like to grow up, and starts to resent it all. It's not fair, life has never been fair, but it's one thing to not be able to date your stepbrother (or that he was her stepbrother at all) and another thing entirely that someone would hurt Emily in such an awful way.

Things go back to normal, after Emily moved back home. The school year passes quickly, Casey's classes are getting harder, and Derek is starting to really get ice time during games.

Their lives still spin around each other, but they've either gotten over the constant need for each other or it's cooled to something they can bare. They aren't careful around each other anymore, because they've learned to quell the urge to touch the other. She hasn't dreamed about kissing him, and he doesn't purposely stand too close to her, waiting for her to lean against him.

They seemed to find a good place in the relationship, and for a while it seemed like this dynamic could work. It was the healthiest they had ever achieved, so they went with it. It would be okay, Derek tells himself, if Casey didn't seem so sad all the time. He wonders if that's why they're really getting along, because she doesn't have the energy to fight or even flirt.

They continued to get busier and busier, and Casey isn't able to come to all of his games, but she tries her hardest to attend when she could. The games were the hardest for her because his elation when he won was contagious, and it was socially acceptable to hug him in that moment. Despite what she told him while growing up, girls did like a sweaty guy, especially when he's just won a hockey game. They'd all surround him, and he'd grin his stupid grin, and she feel jealous for no reason at all.

He comes to her dance recitals, but it's almost too hard to watch, because it's an activity that's specifically meant to watch the movement of her body. He could watch forever, and that wasn't brotherly or healthy at all.

The fantasies start again and the lust and desire return as if they had never left at all, so he stops coming. He recognizes that he's always the one who ruins it when they're at a good point, and he understands that kissing her, touching her, or any of it, would certainly ruin it all over again.

She's upset that he stopped coming and he knows it, but she doesn't say anything.

He feels a little disillusioned with the world. He always thought things just worked out for him, but there's no real way to work this out, no way to make her not his stepsister.

She learns to accept that there simply are things in the world that she can't change.

Their relationship is still amicable, but it's twinged with sadness and regret. Casey feels shame, and Derek feels extremely tired.

The first time they admit their feelings out loud to each other, they're drunk.

This version of Derek and Casey is their friends least, both seem deflated and it's not fun to be around. They seem feed into each other's misery.

Their friends devise a purely university plan: drink the pain away. They throw a big bash - at the guy's apartment, obviously, as there was no way the girls would risk their security deposit. Brett thinks getting Derek laid will help. Tyler and Eric think it should be Casey, but Brett knows better. He might not understand it, but Casey and Derek are weird about each other. That's the truth of the matter. He was beginning to think Casey and Derek weren't as inevitable as he originally thought, and it wasn't really his business.

The girls thought Casey could use a cute distraction. Sarah had long since given up Derek being the cute distraction, and she arranged for several options to be at the party. Casey was hot, and she needed to be reminded of the fact.

Natalie decided to stay out of it. Casey was scary when she was mad, and she knew despite their ever-changing dynamics, they'd always be weird towards the other's significant others.

The whole night very clearly had disaster written all over it. Casey ended getting way too drunk. She told Sarah's date suggestions off, and went as far as yelling at Sarah, which she immediately regretted. Derek didn't take the bait either, despite a parade of girls in short skirts.

The alcohol did provide Derek and Casey with the perfect excuse, however, to throw the freaking line they'd always toed out the window.

She's just gotten done yelling at Sarah when she turned on him.

"You!" She shouts, pointing her finger at him and hitting him in the chest.

He throws his hand up in mock surrender, because frankly he hasn't done anything wrong. He's wanted to do something very, very wrong, for so fucking long, but he hasn't acted on it because of her rules. So she doesn't get to yell at him. If he wasn't so drunk that logic wouldn't have worked, but it did and he was.

"Me." He said, his smile mocking.

She groans in frustration, already annoyed because she knows how these fights always end. "You're going to do this, then?"

Their friends stare at them. They'd never seen this type of fight. Eric coughs that they should get a room, but Casey and Derek ignore him.

"Do what?" He demands. "I haven't done anything at all."

"You're always doing something, Derek. You're always doing something to drive me crazy." She shouts.

"Did you ever consider that you're actually just crazy? Because I haven't done anything."

"Nice, Derek. Really. Fucking. Nice." Her face is flushed, and she steps closer to him, invading his personal space. He refuses to step back and give her the upper hand. If she's uncomfortable with the fact that their chests are grazing each other's, she can move away.

"What did I do, exactly?" He demands, taking a step closer. Their noses are touching now.

He remembers why he liked fighting so much, and why everything was a competition between them. It's so fucking hot, and it's not fair.

"You were supposed to come to my show yesterday, remember?" She's using her princess voice, and it's turning him on. It shouldn't be, but it is. It always has.

He suddenly remembers that their friends are watching.

"C'mon, Casey." He said, stepping back and pulling her into his room.

"Really?" Tyler questioned. He had been enjoying the show. And maybe, just maybe if they'd kissed or fucked or something, they'd stop being such a buzz kill to be around.

"Yeah, really." Derek said, before shutting his bedroom door tightly.

"I had to stop going, Case." He said, gentler than before.

"Why?" She demanded, still upset.

"You know why," he said quietly.

"No, I don't. That doesn't make sense!"

"It doesn't make sense?" He was angry now. "The whole idea is for the audience to watch your body move. You're an amazing dancer, Casey, but watching you dance makes me remember how badly I'd like to touch you. It makes me think of all the things I've always dreamed of doing to you but can't."

He's done it now, officially pushed past the line. There's no way she can ignore that. As it turns out, she doesn't want to ignore that because a second later, her lips are on his.

He's drunk and she's drunk, but the kiss is actually sobering because it's better than either of them imagined.

There's too much sexual tension for their kiss to be innocent. They've both wanted this for five years, and once they start, it's impossible to stop. His hands start on her waist, then move down to her hips, then come to rest on her butt. It's wonderful because, God, it's as firm and perky as he's always imagined it would be. His lips roam her neck, and she arches herself, so he has better access, shifting their bodies even closer.

Her hands run up his arms and chest, roaming freely and roughly. They eventually find purchase on the small hairs at the bar of his neck, and she uses them as momentum to get closer. She's the one that removes the first piece of clothing - his shirt flung to the floor with a gusto he hadn't been expecting.

He raised his eyebrow at her and she smiled dangerously at him, "I wanted it off."

His dick twitches because fuck that's hot. "What else do you want, Casey?"

She stares at him for a second, before he continues. "You've waited five years to control me. Now is your chance."

She doesn't need to be told again. "Take off my shirt."

"Gladly." He complies, quickly shedding her of her shirt. "Now what." He's a little distracted because she's running her hand just under the top of his jeans.

"Now my bra." She says, and he's glad to do that task too.

He doesn't touch her, not yet, because she's in control. He takes a step back. He's dying to reach out to her, but it's important to him that it's on her terms. It's also incredibly sexy, but that's sort of moot.

She runs her hand down her sides then back up her chest, roaming over her very perk boobs. His eyes follow their movement.

"You don't want to touch me?" She asks, even though she can clearly see he does.

"I'm waiting for you. You're in charge. Tell me what you want me to do."

"I want you to touch me." She says slowly. "Then I want you to take off my pants."

He steps closer to her then, and under her instruction, he runs his hands all over her naked chest. He kisses her neck, as his handles fiddle with her nipples. She moans softly, urging him to continue. He complies, pinching and pulling lightly.

Her hips squirm slightly, and he knows what she wants. He lets his mouth travel lower, paying special attention each breast before moving downward. When he hits her navel, he gently guides her to the bed, laying her down on her back. He continues to kiss her lower stomach, and runs a tongue right about her jeans. She moans again.

"Derek." She says in her princess voice. "I said to take off my pants."

He responds quickly, dragging his head down her legs with her pants, kissing every inch of her exposed legs. Her hips twitch and he can smell her arousal.

Even if he wanted to (he really doesn't), there's absolutely no turning back because, fuck, she's so turned on and it's him that's turning her on.

"Now what, princess?" He asks. She's always hated him calling her that, but as he reaches up to fiddle with her nipple, head dangerously close to her underwear, while he waits for her next command, she can only find it incredibly alluring.

"You know what I want." She said, arching her hips upwards.

He's almost undone by that admission alone, but he needs her to say it. Needs to hear it because otherwise he's not certain he's allowed to.

"I'm not sure I do." He urges, and despite his husky voice, she picks up on the undertones of him needing her permission. "Tell me."

"Derek!" She begs, and his dick twitches at the sound of his name from her lips, while she's dressed only in underwear on his bed. "I want you to take off my underwear."

"And then?" He prodded.

"I want you to kiss me!" She said, locking eyes with him.

"Kiss you where?" He wasn't going to allow her to get away without saying it. Somehow the dynamics have switched and now he's in control, but it's important to him that she says it out loud.

"Derek!" She uses the princess voice again. "I want you to - to go down on me!" She demands.

He was hoping for something a little more explicit, but it's Casey and she's demanding he eat her out, and he has no desire to say no to her.

He takes his time removing he underwear, kissing her legs the same way he did when removing her pants. He kisses his way back up her legs, taking his sweet time with her inner thighs. Her hips buck because she needs him, now.

"Derek!" She begs, annoyed, "Now."

"As you wish, keener." He breathes. Of all those times he called her that, he never imagined she'd be this keen for his tongue on her.

She moans when his tongue finally meets her clit. He tried to be slow about it, but goddamn, he'd dreamed about it too many times. Her hands were in his hair, and she's moaning his name. His left hand joined his tongue, and he moves his fingers in and out of her, while his tongue circls and lapps at her clit. She wasn't being quiet, and they were both sure their friends could hear, but it doesn't matter because it's his name she's moaning again and again.

It felt so good, so wonderful. After five years of waiting, it was exactly what she needed. She cums quickly and loudly. It was perfect.

He watched her cum, on his knees with her legs spread around his face and he knew, this moment would be burned in his mind forever. There was no going back now. He allowed her a few minutes to come down, her breathing erratic.

"Am I still in charge?" She asked. It was so typical Casey, but her voice was low and sultry, so what was a guy to do?

"Yes." He choked out.

"Good, because it's your turn."

Fuck, that's another thing he'd never forget.

"Take off your pants." She demanded and watched as he did so. "Now your boxers."

And then he was bare before her. He was so hard it hurt, but he let her take her time. It was only fair. The agony was part of the pleasure; it always had been.

She kissed his neck and then moved lower, crouching down, before settling on her knees, eye level with his dick.

She ran her tongue over the tip, and he couldn't suppress his moan. Her hand came to lightly massage his balls, just as she took the tip of his dick into her mouth.

She had a horrible gag reflex, so she used her hand, and pumped with her hand and head, creating a steady rhythm while her other hand massaged his balls.

She increased her speed and the pressure of the suction and Derek moaned loudly again. He tried his hardest to stay still and not thrust into her mouth, but his hips twitched with his dick, and she knew he was close. She started moving a little frantically, and Derek moaned again, her name on his lips as she came.

"Fuck," he said. "That was amazing."

She pushed the shame down because in this moment he most certainly was not her stepbrother. Perhaps he never had been.

He stepped closer and kissed her greedily. She pulled away, if ever so slightly. "Derek we can't have sex."

His bubble popped, and doubts flew around inside his head. She must have noticed the look on his face.

"We can't have sex because were drunk, Derek." She clarified. "We owe it to ourselves to be sober. We've waited this long."

He sighed in relief and kissed her again. "Well then. We'll just have to see how many times I can make you cum with my hands and tongue."

She gasped in surprise, but found she was completely content with his plan. That's exactly how they spent the rest of their night, with their hands and mouths all over each other. They called it a night when they're hangovers started to form and they both drifted to sleep.

She woke up with a throbbing headache, completely naked, with Derek wrapped around her. She wouldn't have moved, but she really had to pee.

She finds her underwear in a heap, but there's absolutely no way she's pulling on her tight jeans and top, so she settles for a pair of Derek's sweats and a t-shirt that are lying on the floor. She has to roll the sweatpants a couple times, and they land a little too low on her hips, but it'll work for a bathroom tip (and for her eventual trip back to her apartment).

She comes out of his room, to find all three of Derek's roommates staring at her.

"I'd ask you how your night was," Brett begins. "But we have incredibly thin walls, and I unfortunately already know."

She blushes, but all three boys grin at her, and she laughs even though she's still embarrassed.

Derek saunters out of his room, awoken by the noise, in just his boxers. He has a content grin on his face and looks completely unashamed when he suggests that his friends invest in headphones, as he has no intentions of being less noisy.

It's a completely Derek thing to say and it makes Casey blush like crazy, but their friends are happy for them, so it's all okay.

The first time they have sex, it's a week after the party. Casey insisted that they go on a date first.

"I'm not that kind of girl. I'm not even the kind of girl that has sex on the first date, but for you, I'll change my ways."

He laughed. He didn't mind taking her on a date, or even waiting a few days to have sex (because sex had never been on the table before, so honestly, he was just glad even the possibility existed for them).

"Case, we've been going on dates for like five years."

She giggled because it was kind of true but also kind of not true, "We still have to go on a date, Derek." She reminded him.

He found that he kind of liked how bossy she was. He was sure it would still annoy him, but now that he could admit that he found it hot, it was definitely less bothersome.

"I know." He paused. He didn't want to break the spell they were under, but he had to say it. "Case, I'll never be the guy that wants to celebrate month anniversaries or to sing you sappy love songs or any of that shit."

"Derek Venturi," she said, with her princess voice. "Do you honestly think that I don't know who you are? After all this time?"

He shrugged, feeling self-conscious. She did know him, but he also knew her. He had seen her with her previous boyfriends, and he knew what she could be like. He wanted to make her happy, but he knew he couldn't be someone he wasn't. He voiced this, with a shaking voice, fearful that he was ending this before it even started.

"Derek." She said softly. "Did you ever think that the reason I was like that with my other boyfriends is because they weren't what I really wanted?"

"What did you really want?" He asked, grinning because he knew the answer. They had both always known, that's what had made it so damn difficult.

"You, stupid." She teased.

He smiled at her and leaned down to kiss her.

Their first date was a disaster. Derek tried to be sweet but told her to only expect it on special occasions.

"Us having sex is a special occasion?" She grinned.

"Yes." He grinned back. "I've only been imagining it since that time you walked by me in that pink little towel."

"That was years ago, D." She giggled.

"I know." That came out huskier than he meant because he had wanted this for years, actual years.

She kissed him again, and the kiss was super intense, and they almost broke their resolve to wait until after the date. Almost. Derek would have happily forgotten the reservations he had made, but Casey had her rules, and for whatever reason, it was important to her.

He had made reservations at a fancy French restaurant. Pierre, the French exchange student, had recommended it, and Derek thought it'd be perfect and romantic.

They hadn't expected to see their high school teacher, Mr. Roberts - who knew they were stepsiblings - at the restaurant. Casey lied (poorly) that they were celebrating something or other, Derek faked laughed, and the two bailed.

The ended up at the pub they went to every other week, which Derek felt was lame, but Casey didn't mind. Their friends were there, and they were over dressed, but their meal was good. They laughed as they ate, exchanging meaningful glances. Casey declined dessert because she didn't want to be too full - their night was far from over.

She blushed on the car ride home because she couldn't believe she was about to have sex with Derek. The mood shifted in the car as they neared their apartment complex. Nervous anticipation filled the air. Neither said much during the drive.

She knew, even then, that there was time limit on their relationship. That they would have an expiration date, and it would hurt worse than anything else she'd ever experienced. She knew their family would never understand, could never understand.

Because Edwin was her brother and Marti was her sister, the same as Lizzie. George was better than her dad, he certainly cared a whole lot more. Simon actually was their brother, sharing both their blood.

She didn't know if he knew, but she supposed it was for the best. They were a ticking time bomb, and they'd surely take everything down when they finally exploded. She wasn't sure how long they'd have, and she'd surely try and make it last as long as possible. In truth, it had been so easy to fall in love with Derek, that she hadn't even know she did until it was too late.

He wouldn't be able to handle it, this timeline built to end. She knew that, but she'd take what she could get for as long as she could.

It was by far the most selfish thing that Casey would ever do, for so many reasons.

They barely made it to the elevator of their apartment complex before cloths started coming off. The made love in the family room of his apartment, her dress hiked up and scrunched down to a ball on her waist. He'd later rip the dress trying to get it off her.

She rode him on the recliner (he insisted on bringing it with him when they left for school). It squeaked terribly and she honestly thought it might break. He was both incredibly sweet and frantically passionate.

They fucked on the counter later that evening - hard and fast, with Derek's fingers at Casey's clit the entire time. She screeched his name and dug her fingernails in to his back until he bled, but neither of them cared.

They made it to his room before Brett, Eric, and Tyler came home from the pub, and made love in his bed. He whispered to her the entire time about how beautiful she was, how perfect. He said the mantra she had always seen in his eyes, every time she was with a different guy: mine, mine, mine. She reveled in it because she was his, and he was hers.

She never spoke about their timeline. He never realized (or was never brave enough to allow himself to realize) that their relationship would expire. She knew this because for all of his declarations of extreme masculinity over the years, it was he who couldn't handle it, not her.

He finally felt like he was winning in life, like he could have everything they wanted.

They never told their parents, and both made excuses to stay at school for the summer. Casey for summer school (which wasn't actually an excuse, she was double majoring, thank you very much). Derek got an internship, which he actually excelled at. Then hockey camp started, and it just made sense.

They visited home at different times, and the family joked that the house would implode, if they ever saw Derek and Casey at the same time ever again. Despite their separate appearances, their parents were grateful that they had each other, some semblance of family when they were away.

If only they knew.

Sam could tell, the first time he saw Casey. Derek, being the Lord of Lies, hadn't let it slip, of course.

"I hope you know what you're doing, Case." Sam warned, and the words haunted her.

"I do, Sam. I really do." She assured him, and she did. She always knew.

He looked at her with a sad smile. "That's what scares me."

Their friends would tell acquaintances that Derek and Casey were the reason they believed in love, though they never uttered the words to one and other. Derek thought it was too cheesy, and believed that Casey knew, which of course she did.

Casey thought it'd make things too complicated in the end, as if that would actually make a difference.

Casey kept her room in Natalie and Sarah's apartment, at least as a closet and a clean shower or a quiet place to study. She paid rent, of course, but she lived with Derek.

Their junior year flew by.

They were a perfectly imperfect couple. Derek had been right, it did annoy him when she was bossy, but it was still hot, and he had found much, much better ways of shutting her up then when he was in high school. They still fought, and their drive and competitiveness hadn't cooled over the ages. They learned to pick their battles because they couldn't stand being a part.

And the sex, dear god, the sex was amazing and frequent. Brett did end up buying those headphones after a few weeks.

The holidays were the worst. Casey always made up some reason not to go home for Christmas and Easter. Derek argued with her, telling her he should take a turn, but Casey always won. It wasn't that Derek was afraid to fight with her - he certainly was not - but she always won. He didn't put up much of a fight, not really.

He wasn't being selfish, because once they started dating, he was rarely selfish when it came to her (except maybe their whole relationship was selfish, but that's neither here nor there). She was inflexible on this, and he didn't really understand why. They had agreed to wait until after they graduated to tell their family, so he understood the necessity of one of them staying home, but she was relentless that it was always her.

She insisted it was because she was a bad liar, but in reality, she viewed this as her penance. She knew, and Derek didn't, so she would suffer the lonely holidays. She loved holidays and she missed her family, so in a way, it was penance, indeed.

Her mom called her crying on the first Christmas she missed, and Lizzie threatened to come drag her ass home, but Casey was determined, so Casey won. She cried on Christmas and on Easter too. She made herself boxed Mac and cheese and watched the most un-holiday shows on TV. Edwin wrote her a letter, trying to understand why and Marti refused to talk to her for a few days. Simon was too little understand, but he asked his parents where his "Cee-Cee" was.

She came home a week later, and Derek left early so she could. Derek fed their family a lie about how they'd had a fight, and it was for the best. Casey kept that lie going but refused to talk about it (because eventually someone could uncover the truth).

George and Nora sat Casey down and begged her to work it out with Derek after they were forced to celebrate Easter twice, once with Casey and once with Derek. They told her that they thought it was getting better between them, and Casey stared at the wall. She responded with half-truths: Derek and her would never really be brother and sister; they weren't wired that way. It was the truth, but her parents would never guess the true meaning behind it.

Derek began to hate the holidays; he couldn't spend it with the person he most wanted to spend it with. He began to consider telling their parents, but Casey begged him not to. She argued that they'd force them to change schools, that the life they'd built - a very, very happy one, mind you - would be destroyed. It was better to wait until they were truly independent of their parents, that way they could stand on their own, if they needed to. They only had one more year of the deception, after all.

There was truth to her words; it was exactly how Casey imagined her parents would react. And they really did only have one more year of deception, he just didn't realize that he, too, was being deceived.

Her parents pressed for details about why they suddenly hated each other, but neither would budge. The truth would be worse, so they both thought it would be best. Derek began to struggle with lying to his parents. Casey teased him that he was finally maturing.

Truthfully, Derek was a little worried about pushing her too hard on this subject, afraid of the consequences. The first line of their relationship was drawn. Derek wasn't too worried; crossing lines was their specialty.

Casey still knew, and it was the biggest lie she had ever told. Maybe, just maybe she wasn't as bad of a liar as she had always thought.

Lizzie almost found out, in February of their junior year. Matt broke up with Lizzie in the most heartbreaking way - in front of everyone at a school dance.

Lizzie stole the keys to the car that she and Edwin share and drove straight to Casey. It was lucky that Casey had a test the following day, and actually was in her room when Lizzie arrived.

Casey held her sister while she cried. They stayed up the whole night, talking, crying, and laughing. She texted Derek while Lizzie was in the bathroom, and they agree to take her out for breakfast and then send her home.

She tells her roommates that her sister is too upset for company. They're all curious - they haven't met any of Casey's family. Casey wakes Lizzie up at 5:00am and Lizzie is perplexed when she discovers that Derek is also awake.

"I thought you two hated each other or something?" Lizzie asked.

"We do." Casey said quickly. "We called a truce because we both love you."

Derek looks down. He really, really is starting to hate the lies. How could anyone believe that he could actually hate her is beyond him. Although, he supposed he was convincing for a while.

Lizzie didn't buy it. And despite how upset she is, she notices... things. Like how Derek's eyes follow Casey around the room, and how Casey finishes Derek's sentences. Or the fact that they don't snipe at each other once, even though they are supposed to hate each other. Even when they got along in the past, they still couldn't help sniping at each other. Its weird and uncomfortable.

But it doesn't make sense. Why would they lie? Maybe Lizzie doesn't really want to know, because she pushes the feeling that something isn't right down and ignores it completely.

She even lies, once she goes home, and says she didn't see Derek at all because it was all just too weird, and she didn't understand. Casey knows that Lizzie sort of knows, but she doesn't think that she'd ever tell, so she talks herself out of her panicking, and tells herself that their time isn't up. Not yet.

She thanks God that it's not yet.

The summer before their final year of university, she gets an internship at a law office and Derek gets a job coaching hockey camp for youth groups with the university.

He absolutely loves it, and he realizes he may have found his calling by accident.

Derek gets his own apartment, and Erik, Tyler, and Brett move into the three bedroom apartment that Casey, Natalie, and Sarah used to live in. Natalie and Sarah move in to a two-bedroom apartment.

Without really discussing it, Casey and Derek move in together. It's a tiny apartment. There's not nearly enough closet space, but Casey is creative, and Derek would throw everything away if he had to, because it's perfect.

Casey still knows, but playing house is perfect and wonderful. She's going to have to give it up, so she's going to enjoy for as long as she can.

She has a year. One year, and then she'll fix the mess she made.

Their parents want to visit, but they both Derek and Casey say they'll come to them. For the first time, Nora and George question the logic that's persisted for so long. The kids are older, and they have more time on their hands, so the lie of convenience starts to wane.

It happened on a Tuesday night; Casey knows because she was in a night class about libel law. Her phone rang once, and she hastily shut it off before her professor kicked her out of class. It rings again, this time on vibrate. And then again. And then again. She grabs her bags and slips out the back of the classroom as quietly as possible, knowing something must be wrong.

She answers her phone with shaking hands. It's her mom. She can barely understand her through the sobs, but she hears Marti and hospital, and sprints back to her apartment. Derek is waiting, face pale and voice shaking.

She drives because Derek's hands are shaking too badly, proving what she knew all along: of the two of them, she's the one that can hold it together.

They sleep in the lobby of the hospital, or at least they try, as they wait for the news.

Lizzie and Edwin fill them in on the details, filling in the gaps when the other gets too emotional. Marti had always been different, special. But the bullying only got worse. Just when they thought it couldn't get worse, it somehow got even worse. Marti took pills, which caused a seizure.

Lizzie found her, and they had her rushed to the hospital.

"How could you not tell us?" Derek demanded. "I didn't know it was this bad! Did you?" He turned to look at Casey.

Casey shook her head, unable to keep it together. She sobbed and Derek wanted to go to her, but he knew he couldn't. Lizzie held her and cried as well. Edwin leaned in too, hiding his tears behind Casey's hair. Derek stood by himself, refusing to cry.

He yelled instead. At George and Nora for not telling him. At the horrible little shits that would bully such an amazing person. At the school for letting it happen. He wanted to press charges against Marti's bullies. He calmed down after 20 minutes of yelling, and then he really did cry.

He apologized when he calmed down, but his hands still shook. Out of fear or anger, he wasn't really sure.

Marti pulled through the night, and the doctors said she'd get better, but they placed her in a psych ward. They got to see her before, for 20 minutes, and then they took her. The hold was for two weeks; they could visit, but only for an hour or two. Everyone knew it was for the best, but it still fucking sucked.

Derek and Casey stayed at home. If anyone noticed their dynamic, no one said a word. The truth was everyone was too wrapped up in their own grief to notice.

They mostly avoided each other, except at night, when Derek would sneak into Casey's bed. He'd leave before anyone woke up, of course. It wasn't sexual in the slightest. He just needed her. Marti's suicide attempt shook him to his core. He missed their tiny apartment, where he could seek Casey's comfort without fear of their secret being discovered.

When Marti was released, Derek had a long talk with her. He told her to call if she needed anything, and he vowed to be more involved.

They left after a week; their parents told them they had to. Missing anymore school would push them back, and they were only a few hours' drive away. George and Nora promised to keep them updated.

Marti transferred schools. Time healed, though it was slow.

Derek's view of the world had been deeply shaken, and Casey did her best to keep him afloat. He ended up dropping his classes for that semester. The school made allowances for him, siting a family emergency. It was a miracle he didn't lose his hockey scholarship.

Casey went home for Christmas and so did Derek. How could they not after all that had happened? Derek and Casey avoided each other. Casey wouldn't let him in to her bed, it was too risky. The family was functioning better now, and someone would notice.

It was only for a week, but fuck did it feel wrong.

Christmas was a muted affair, but Marti told them all to stop treating her like she was broken, and that began to break the ice. She made jokes and Derek joined in, desperate for something because in this house he couldn't hang on to Casey for balance.

It returned to semi normal.

Casey threw herself to in to taking care of Simon. She played with him constantly, and he loved every second of it. Derek watched them, when he thought no one else was looking. She was perfect with Simon, and he realized she would make a wonderful mother.

That thought should have scared him. If 16-year-old Derek knew what he was thinking, he'd have punched himself. It didn't matter because he wasn't 16 anymore, and Casey was his lifeline. In a way, she always had been.

He re-enrolled in the classes he dropped when they returned to school. She helped him with his school more than she should, and Derek slowly returned back to normal.

The last semester hadn't gone how she planned, but she could still make the best of the time she had left.

The acceptance letter for a law school in New York came on a Wednesday afternoon, and she purposely did not tell Derek. She began to make her plans. She had been accepted on a partial scholarship, and she enrolled for university apartment living. She'd have to find a job quickly to pay for it, but it would better than living with a stranger. After living with Derek, she wasn't sure she could live with anyone else ever again.

She made the most of the time she had left with Derek. They went on dates and spent every moment together. They made love almost every day, sometimes more than once. She kissed him with reckless abandon, giving him all of herself, at least for a little while longer.

She didn't break until three weeks until the end of the semester. Derek wouldn't graduate on time, the missed semester pushing back his graduation date, but Casey would. It was a rare night where Derek didn't go out and she did.

She met Brett, Natalie, and Sarah at their favorite pub and drank way too much, way too quickly. Sarah threw up in the pub's bathroom, and Brett took all three girls back to his apartment. It was weird, she reflected, she'd lived there for two years, but her and Derek's apartment felt more like home than anywhere else ever had.

Natalie and Sarah eventually walked back to their apartment (it was only down a flight of stairs).

Brett peered at Casey for a few moments. "Alright, out with it. What's wrong?"

Because somewhere along the way, Brett went from being Derek's best friend, to being their best friend, and Casey wouldn't have traded that for the world.

"I got accepted to law school. In New York." She finally said.

"When?" Brett said, completely caught off guard. "I didn't even know you applied."

"Three months ago." Casey replied calmly. "I've accepted. I move into my apartment in July."

"Does Derek know?" He asked because frankly his head was spinning.

"No."

"No!?"

"No."

"Fuck, Case." Brett swore. "Why?"

She sighed and contemplated lying, but she needed at least someone to know. And she figured he could help Derek once the dust had settled.

"Derek is my stepbrother. My mom married his dad when we were fifteen." Casey said after a moment. "We met before we knew who the other was. I knew then, who Derek would be to me, and then spent 5 years fighting it. The last two years have been perfectly amazing."

"But?" Brett prodded, always the optimist.

"But it isn't sustainable. Our parents don't know. We share a brother; did you know that? A brother who is related by blood to both of us. Even if we didn't, Edwin is my brother, even if it's not by blood."

"So, the family emergency we never got details on?" Brett asked.

"Our sister, Marti attempted suicide."

"Fuck, Casey." Brett said.

"Do you plan on telling him, or just leaving in the dead of the night?"

"I haven't decided yet." Casey said honestly. "I'll probably leave a letter."

"That's chicken shit." Brett said. "You have to tell him. Because you're not just leaving for school, you're leaving him."

She nodded slightly, confirming what Brett already knew. She collected herself quickly because tears were starting to fall down her cheeks, scolding herself.

"Why?" He asked again.

"It isn't right. It never was. He's supposed to be my brother."

"What am I supposed to do with that?" Brett demanded.

"I don't know. I've never known what to do with it." Casey answered honestly.

"I can't convince you to stay, can I?"

"No, I have to go. I always knew I would."

"Does Derek know? That there is and end date for your relationship?"

"No. He thinks that they'll understand, accept it."

"And they won't?" Brett prodded.

"No. I'm not sure they'd ever forgive us." Casey sighed.

"This will kill him, Casey. He's only started to get back on his feet. Don't do it."

Tears formed in Casey's eyes. "It would be worse when our parents and siblings find out. That's why I'm telling you. He'll need you, after I'm gone."

"You know I love you, Casey, but I kind of fucking hate you right now." Brett snapped.

"It's okay to hate me. It's okay for Derek to hate me. Maybe it'll stick. It'd make it easier. I don't plan on coming back home for a few years. I'd love to say that's enough time, but we couldn't get over each other in five years, so I'm not sure. Hopefully distance will help."

"Casey this is fucked." Brett asserted.

"I'm giving him the family, at least temporarily. I'm giving up everything, except for my career, to fix the everything we fucked up."

"He loves you." Brett pleaded.

"He's never said it." Casey admitted. "Not when we were playing at being brother and sister and certainly not when we were playing at lovers."

"I know there's a value on the words 'I love you' but he doesn't need to say it, Case, for you to know it."

"You're probably right, but maybe he hasn't said it for the same reason I haven't. Our relationship was never meant to last. We had two years, that's more than most people get."

Brett shook his head. He was too drunk to process this further.

"Just promise me you'll take care of him." Casey begged.

"I will."

"I will," he repeated as she stood up to leave. "But it should be you."

"In another life, it would be." She replied, and then she left. She wouldn't talk to Brett for another three years.

That was the real reason she had this conversation so soon before she left: she was giving Derek Brett, too.

Two weeks before the semester ended, and one week since Casey and Brett had their talk, Derek was sitting in Brett's living room.

"I think I'm going to propose to Casey," Derek blurted out.

Brett was in the kitchen, with his back turned, and therefore had a few seconds to collect himself.

"What?" He asked, buying time.

"You heard me." Derek said softly. "I know I still have a semester left, but honestly it feels right."

"Okay..." Brett didn't know what to say.

"There's something you should know. It might be a bit of a shock, but Casey and I haven't been fully honest with you."

Brett panicked, knowing exactly where this was going, but Derek didn't notice, he had to get it out.

"I met Casey when we were fifteen when my dad married her mom." He rushed out. "We're step siblings, which is super messed up, but God, I've never loved anyone else more in my life."

"I know, Derek." Brett replied. He couldn't lie to his best friend. "Casey told me."

"What?" Derek asked, stunned.

"She told me last week after the bar. She was drunk." He offered.

"You're okay with it?" Derek asked. Brett nodded because the stepsiblings thing wasn't even the most fucked up part of it all.

Derek took a relieved breath. "You're a good friend." Pause. "Casey didn't tell me she told you."

"Yeah, Casey hasn't told you a lot of things," Brett grumbled.

"What?" Derek questioned, utterly baffled now.

Guilt surged through Brett. "Look man, I'm sorry I have to say this. It really shouldn't be me. Don't buy a ring."

"Why not? You said you were okay with it?"

"It's not that she's your stepsister. Look, talk to Casey, okay? I don't want to be in the middle of this, but don't waste your money."

Derek sat there, dejected for several moments before getting up and leaving.

The argument that ensues is ugly. Truly ugly. Casey breaks down and tells him everything because she can't continue to lie to him any longer.

He begs, he's embarrassed to admit. He'll come with her, after he graduates. It won't matter if George and Nora don't approve; they'll be in a different country. It's a tempting offer, and maybe if Marti hadn't attempted to take her life, she would have considered it. Derek can't leave the country, can't leave Marti.

He blinks back tears and begs again. There are other schools, closer schools, he argued. They could keep their relationship a secret. It didn't have to end.

But it did. It really, really did. Casey had made up her mind, years ago, when she crossed the uncrossable line. She couldn't go back on it because there was no future for them.

He nodded angrily at her, his tongue pressing against his check. She knew that look anywhere; Derek was royally pissed off. He went into their room, pulling something out of one of his drawers.

He tossed it at her, and it took a second for her to process what it was. A velvet black box.

"Derek," Casey sobbed.

"You're not even going to look at it?" He demanded. "It's not much, but I saved everything I could for it."

That broke her heart, and she held back another sob. She opened the box. He was right, the ring was small, but it was lovely. It was a silver band with a simple oval diamond. She fought the urge to slip it on her finger.

"It's beautiful, Derek." She said softly.

Derek looked up, hope swimming in his eyes. "We'll make it work. I know it seems hard right now, but we can make it work. Dad and Nora will understand when we tell them. We fought it for five years, and it's not just a passing phase. They'll see how serious we are."

It sounded so good, but she knew that's not how it would go down.

She walked up to him, and he watched her, stalked her really, with his eyes. She placed the ring box back in his hand.

"It's beautiful, and I want you to know how much I truly, truly wish we could. Our family is already in shambles, Derek. This would destroy them. Us getting married would break the family down, make the Venturis and the McDonalds separate entities, but they're not. They're one beautiful, perfect family, and we're the only ones who couldn't get it right."

"Don't do this Casey." He begged.

"I have to." She said. She stood up and starting packing her things. She had really wanted the last few weeks with him, but she supposed this would have to do.

"You knew this would happen from the beginning?" Derek demanded, following her into their bedroom.

"Yes." Her voice was quiet.

"The whole time. You knew? You knew when we went on our first date? You knew when you moved in with me? You knew?" He was getting angrier and angrier.

"I'm sorry." Casey said. "I know it might be hard to see now, but it was this or never at all. We had two years Derek, two beautiful years. That's more than most people get in a lifetime."

"I love you."

Casey dropped the mirror she was packing, and it shattered to pieces.

"I know, baby. I know." She was choking back tears. "And I've loved you from the second we locked eyes, seven years ago."

"Don't do this."

"We never should have done this at all. This was our timeout from the real world." Casey said.

She grabbed a dustpan and broom and began picking up the glass she shattered. She cut her hand, but didn't register the pain, not even a little bit. It was nothing compared to the pain in her heart.

He ran to the bathroom, slamming the door. She could hear him vomiting even with the door closed.

She packed quicker now, not taking the time to organize anything - in a completely un-Casey manner. Her hands were shaking.

She stopped packing. She could still hear Derek vomiting in the bathroom.

She called Natalie. Brett hadn't told anyone, so they had no idea what was happening, but Natalie agreed to Casey sleeping on her couch until the end of the semester.

She had packed most of her clothes by the time Derek left the bathroom.

"I'll come by tomorrow with some boxes for the rest of my stuff." She told him briskly.

Derek stared at her, completely numb.

He ends up packing most of her things because he can't bear to look at them, which she picks up after her last final. They've agreed that she'll go back to their parents' house, and he'll stay on campus. That there's no need to see each other again before she leaves in July.

He doesn't say much to her because she's stolen all his words. Stolen his heart, too, if he's honest.

He doesn't help her load her car, but she supposed that's fair.

They don't say much to each other. She looks around at the half empty apartment one last time, and this time allows the tears to fall. This was her home, and her life had been perfect. It was just too fucking bad that it had all been a lie.

"If you change your mind," Derek says, because his pride is dead. "I'll be waiting."

"I won't, Derek. I hope one day, you can look back at these past two years as happy memories. Despite it all, I'm wouldn't have traded them for anything."

"Sure." He said, bitterly.

She stares at him, and he stares at her, and then suddenly they're kissing.

He tears at her clothes, ripping them off with little care to any possible damage. She's just as savage, her fingers desperate to rid him of his clothes. They start out quickly, but Derek slows their pace, moving in and out tortuously slow. He plays with her clit, because it's habit and because he wants to hear her moan his name.

"You'll never find anything like this again," he warns aggressively in her ear.

"I know." She responds. He's in control, and she's letting it happen because he's right. She'll never feel like this again, not ever.

"Will I see you again?" He asks, as he speeds their space slightly.

"Not for a few years," she admits.

"I'll miss you every second." And with each word he speaks, a little piece of her heart chips away. She wonders if she'll ever be able to put the pieces of her heart back together.

She can't take it anymore and speeds up their pace. She cums shortly after, but he's not done, so he lets him continue, matching his rhythm.

"I love you." He chants. "I love you; I love you; I love you."

She doesn't say it back, because he knows, but he also knows it doesn't change anything. He finishes shortly after, and he can't stop the tears that form in his eyes.

"I shouldn't have let that happen." She says in way of an apology.

He nods and blinks back tears. Then watches her dress and leave.

After his last class, he calls Brett and he comes over, but fuck, it doesn't help at all.

She has to pull over on her drive home because she's crying too hard.

She spends the entire summer devoted to her siblings, paying special attention to Marti. Her parents are surprised by the news when she tells them she's going to law school, but so, so excited for her. They wish she wasn't going so far away, but they get it.

When her mom asks her, two weeks after she moves back in, if she wants to talk about the boy who broke her heart, Casey can't answer. She's lost her voice momentarily, and Nora just hugs her. She doesn't cry. She swears she lost the ability when she left Derek for the last time.

Casey moves forward and begins to get excited about New York. Lizzie sleeps in her bed most nights because it feels like a chapter in their life is ending, and neither sister wants to let go. Marti joins them in the middle of June, and then Nora gets involved, because her girls might be small, but the three of them in one double bed is ridiculous. Nora buys an air mattress, and even spends a few nights there, because it is the end of an era, and nothing will ever be the same.

Casey pays special attention to Edwin and Simon, spending time with them as well. The summer days pass quickly, and Casey's heart breaks even more because she loves this family so much. She loves them more than she loves herself. She'd definitely proven that.

Nora plans a goodbye party and is outraged when Derek says he can't come. George gets involved and a horrible fight ensues. It's Casey who ends the argument, by sitting her parents down.

"I know you always wanted Derek and I to be brother and sister, but you have to let it go." She begged. "It's never going to happen. He's not coming to my going away party, please don't force him. Our relationship is unrepairable, and I don't expect that will ever change."

Nora stares at her and Casey continues. "I'm sorry to disappoint you; I really, really am. But I love this family, so please let me leave without any drama. This isn't about him, so don't make it."

George puts the pieces together, or at least a few, and drives down to see Derek without telling Nora. He isn't prepared for the broken mess he finds in place of his son. He doesn't ask for details because he isn't sure he wants to know. Just spends a few hours trying to console his son and drives back home.

He doesn't tell Nora because it's all too much, but he does get her to stop harassing Derek, because it's only making it worse.

He wants to hate Casey. That broken man he saw was a shell of his son, but he loves her too much. He becomes really supportive of Casey's move, and he understands now why she had to do it.

He blames himself, because how the fuck did they not know?

Sam comes to the going away party. He shakes his head at her because he knows and his heart breaks for her. After all this time, he still hates to see her upset, even when she's the one who caused her own pain.

Derek calls her the night before she leaves. He doesn't beg; he doesn't try to reason. He knows her too well; he knows it'd be pointless. He wishes her good luck through gritted teeth because damn him, he still loves her, and this is her dream.

She steps outside, on the porch they grew up on, and wishes him nothing but happiness and success. He doesn't tell her that she's taken his happiness (she knows because she's taken her own, too).

She drives across the border and doesn't look back. It's what had to happen.

She gives law school her all, and she excels because she's still Casey, despite her broken heart.

She meets Jamie on her first day of class. He's basically a Sam 2.0, but smarter and less easy to manipulate. They're friends for six months before she agrees to go out on a date with him.

She falls in love, and it's a different kind of love then she's ever known. He's kinder than Derek and Truman, understands her much better than Max, and is more perceptive than Sam. He has an uncanny ability to read her, better than anyone, even Derek.

She tells him on her third date, that she may never be fixable; she might not ever get over her ex.

Despite being a mess, a work alcoholic, and having the world's largest set of emotional baggage attached to her, he still wants her. She holds him at arm's length for as long as she can because Derek is still her first and last thought each day. She eventually gives in; she frankly just misses human contact. She can certainly do worse than Jamie Santiago, with his accent and charm.

He isn't bothered by her past, and doesn't push, but he knows something bad happened. He becomes a constant source of comfort, someone to count on. He goes out of his way to make sweet gestures for her, buying her coffee, making her lunch before he leaves for work and leaving a sweet note, showing up after her class to pick her up so she doesn't have to take public transportation.

He's so different than Derek; their relationships are so different, so she doesn't even try to compare them. Because Jamie is wonderful, and the comparison to Derek wouldn't be fair. Jamie is by far the better boyfriend, the kinder person, the better match. She knows Jamie should win the comparison, that's she's definitely not making, but somehow it always Derek who come up winning.

Lizzie fills her in on Derek's well-being, because Lizzie knows, even though she doesn't know everything, and Casey is grateful in a way.

The family doesn't see Derek until August, and when he returns home for a visit, he's loss some muscle and weight. He looks a little swallow, but he smiles and jokes and pranks. Casey is thrilled to hear it, because she couldn't stand an altered version on Derek, not because of her.

He finishes his semester and accepts a coaching position back home. The pay is shit, but Derek loves every moment of it. Derek quickly moves in with Sam, five blocks away, and the two live out their childhood dream of having their own bachelor pad.

Lizzie doesn't tell Casey all of the details, like how Derek felt out of place living at home, like his presence without hers didn't make sense. Even to their family, they had become so intertwined. How sometimes Lizzie would wake up and miss their fights or how she dreams about prank wars and illicit parties or the two just downright scheming together.

Because it feels wrong to Lizzie, this permanent discord between the two. She doesn't voice her opinion. It won't change a thing. Lizzie feels like a part of her childhood has been taken, though she can't put her finger on why. Casey and Derek had been staples in her life, she practically revolved around their antics, and now she barely had either in her life at all.

Marti calls twice a week, on Wednesday's evenings and Saturday mornings. They talk about anything and everything, and Casey sighs in relief every time she hears Marti's voice. Marti wants to visit, and Casey convinces her parents to let Edwin, Marti, and Lizzie visit by themselves.

Her apartment is too small, but Lizzie and Casey share the bed, Edwin takes the couch, and Marti sleeps on the air mattress that Casey bought specifically for the purpose.

She's been gone for six months at this point, and having them here, with no space and fighting over the bathroom, feels just like old times. They bicker a little, like all siblings do, but when they do, Casey's heart throbs a little, because Derek is missing. Her heart throbs a little harder, as she realizes that if Derek were here, it still wouldn't be the same.

She fucked that all up several times over.

Casey takes them paintballing, when Edwin says, "Derek would take us." She's still competitive, but mainly it's because she thinks that maybe she'll feel closer to Derek for just a minute. It doesn't work, and she's gets paint in her hair.

The kids have fun, though. They spend the weekend watching movies and ordering take out.

Casey cried for 30 minutes after they leave. She called Jamie for the first time (at this point he always calls her, and she typically finds an excuse to not hang out with him). He comes over and cooks her dinner. It's amazing and when he kisses her, she actually doesn't think of Derek.

---

Life at in the "Bachelor Pad" isn't super bachelor pad-dy, at least for Derek. Sam has a new date every week, which Derek high fives him for (he's still Derek after all).

He goes on a few dates, even brings a few girls home. It's easy, it always has been. It just feels flat. So, he stops going on pointless dates. Sam teases him, but he's gets it, so he leaves it be.

Derek focuses on his job, which he actually really does enjoy. He picks up a serving job on the weekend for extra cash. He likes it, and it keeps him busy. He has dinner with his family once a week but convinces the family to come to his house or go out most weeks.

The house doesn't feel the same without Casey.

But it certainly doesn't feel the same with her in it either, he discovers, when Casey came home for her grandmother's funeral. Nora was distraught, Lizzie tried not to cry, and Casey tried to take care of them.

Derek tried to stay away, but George said he had to go the funeral, and the reception at their house afterwards. The funeral went on without a hitch. He saw Casey crying but didn't go to her. It felt wrong, but she made that decision for him.

He did hug Lizzie and Nora, though.

The reception back at their childhood house was another thing. Casey was everywhere, talking to their relatives, getting a comforting hug from Sam, telling entertaining stories about her grandma to family friends. He tried to keep his eyes off her, but it was impossible.

Casey's cousin Vicky raised an eyebrow at him, and he turned his attention to her. She smirked at him because they both knew the other was a good kisser, but mostly because she could see right through Derek. Vicky liked to have the upper hand in all situations. She also knew that Derek liked to have the upper hand, too, so it made it even more fun.

"Did you need something from Casey?" Vicky asked.

"No." Derek said, shrugging his shoulders and turning to go find Sam.

"Do they know?" She asked, gesturing to George and Nora.

"There's nothing to know." Derek said, feigning a nonchalant attitude.

She nodded, "Sure." Pause. "Is that why you were into me?" She asks.

"Huh?" He says, though he's pretty sure he knows where this going.

"Because we look so much alike?" She tilts her head in an imitation of Casey that's pretty spot on. "That's really messed up. Even for you."

"I don't know what you're talking about." Derek says and walks away.

Casey had to sleep in Derek's old room. George and Nora had moved back into hers when she left, and she might be 22 years old, she still refused to sleep in the basement. She avoided it the first night, as all three girls piled into Marti's bed and watched movies. She was too exhausted to that for a second night in a row.

The room doesn't have any of Derek's furniture in it anymore, only an air mattress, an end table, and a desk (it functioned as a home office these days). She could almost pretend that this was some different room with no attachment to Derek, except for the memories. How many fights had she had with Derek in this room? How many times had he smirked his stupid smirk at her while laying on a bed in this very spot? She can close her eyes and see it, how they used to be. It's not fair, but it's never been fair.

She ends up crawling in bed with Lizzie, who doesn't question it.

She leaves the next day, saying she had to study, even though she's been given a reprieve for all assignments for her time of bereavement. She doesn't say goodbye to Derek, but she calls him before she crosses the border. He answers on the fifth ring.

"Everyone alright?" He asks. Of course, that's why he thinks she's calling. "Yeah, everyone is fine. I just wanted to tell you I left, so you can stop avoiding the house."

"I'm not avoiding anything." His voice is casual. For the briefest of seconds, she thinks that they might be able to return to semblance of what they were before they dated.

"I miss you." She says. It's the truth.

"What do you want me to say, Casey?" He bites back.

"I don't know. I just thought you should know." She responded. "Do you miss me?"

"That's not fair." He replied harshly.

"I'm sorry." She says, and even though she's been living in New York for close to a year, she still had a Canadian accent. It throws him for a second, though he's not sure why.

"I feel like my life has revolved around you since I met you." Casey admits, pulling over. She's suddenly not ready to leave Canada.

"Okay..." he says slowly.

"It's weird because in New York, you feel so far away. I used to think my world spun in circles around you. Now it feels like it doesn't spin at all."

"Case, I've revolved around you for years. Maybe it's for the best, the distance." He sighed. "You finally have the Derek-free, uncomplicated life you always wanted."

He doesn't remind her that he gave her the option for the exact opposite. There's no point now.

"Does it feel like it's the best, for you?" She asked, needing him to say something to make her cross the border, otherwise she won't go. She'll turn around and run straight to him.

When he replied, she knows right away she's pissed him off. "You do NOT get to do that, Casey. This has always been your choice, not mine. If you want to go back on it, you have to make it right. I can't just forgive you because you miss me."

She's silent.

"Fuck. You don't even want to get back together. You want to go back to whatever the fuck we were before we dated."

"Stepsiblings." She reminds him.

"No, no. We were never siblings." He argued.

"Yes, we were. We always were. We just liked to pretend we weren't."

"You did all the pretending, Casey. Not me." He says and then hangs up.

She sits for a moment before heading back towards the border.

They don't talk for two years after that. She doesn't come home for the holidays, but he already knew she wouldn't. George and Nora never stop bringing her up, which frustrates him to no end. He gets it, though; they're proud of her.

George comes over one Saturday in August after Casey has graduated law school and knocks on Derek's and Sam's door. They upgraded to a nicer apartment than the dump they used to live in. If Derek is surprised by his father's presence, he doesn't show it.

"Did you want to watch the game?" Derek asks.

George agrees, but Derek can tell he's being shady. Sam plops down with them and turns on the hockey game. They sit through the first period without much real conversation, except for cheers and hockey commentary.

During a commercial Sam asks how George feels about Lizzie and Edwin going away for school.

"The house is going to be quiet." George admits, and Derek claps him on the back. He feels a bit of nostalgia too, even if he tries to block out most of his past knowing it's too painful to think of.

"Listen," George begins after the game is over. "I have some news, which I'm sure Nora will tell you tomorrow, but I didn't want it to come as too much of a surprise."

Derek turns off the TV and turns to face him. He has no idea what his dad is about to say, but his serious expression is making him worried. Out of the corner of his eye, Sam shifts uncomfortably.

"Casey is coming home." George says softly.

"Is that it?" Derek asked, relieved. It's not necessarily good news, but he knew it was her eventual plan.

"She's not coming back alone." That stops Derek short, and suddenly he knows where this is going.

"Oh. Is what's-his-name, John with an H or whatever coming with her?"

"Jamie," Sam corrects because he knows Derek knows his name.

"They bought a house, it's about 20 minutes from here." George continues. Derek nods because words are failing him.

Sam watches George and waits. "Is that all?" He asks. "I mean, I can't wait to see Case again, but I'm not sure that warrants a visit."

It's then that Derek realizes that Sam already knows.

"Jamie proposed to Casey." George finally says, and Sam coughs.

"And she said yes." George adds unnecessarily because Derek had already figured that out for himself.

"That's great!" Sam exclaims, filling in the awkward silence because Derek should be saying something rather than just standing there staring, if only to avoid looking suspicious.

"Yeah, great." Derek echoes, but it's hard to swallow because he remembers her saying no to him when he had proposed to her.

He wished he was over it. He just wasn't.

"Derek, I think we should talk." George says. "I don't know what happened between you two, but I know something did."

Sam sits down. A part of him wants to leave; it's massively uncomfortable. He thinks Derek may need a friend, though, so he stays put.

"You have to let it go. I know it must have been confusing with her being your stepsibling and all. I'm not sure, but I'm assuming that she returned your feelings, at least a little bit? Maybe you kissed or... whatever and she freaked out and ran away. I think she did the right thing, D."

"The right thing." Derek said and Sam tried to stop him, but Derek was too mad because how could she say yes to Jamie and not him. "You think we kissed? Or do you think we fucked? You think that's the reason she fled to a different fucking country?"

"It's not?" George asked before he could stop himself. He hadn't come to find out anything more.

"No. No, it's not." Derek's unstoppable now. There were a few times in Derek's life where he could actually be considered cruel for the sake of being cruel, and this moment trumped all of those times. He's heartbroken and angry. Angry at Casey, and his dad, for diminishing what Casey and Derek had to something as simple as a kiss.

It was so, so much more than that.

"We didn't just sleep together dad - though we did do that quite a lot. We were together. For two years. We lived together for fucksake. For a whole school year. Why do you think we didn't want you to come visit, huh? If you would have come to visit our senior year, it would have been to our apartment. It had one bedroom and one bed."

"What?" George asked after several beats. He thought he had an idea what happened, but this was beyond him.

"We weren't stepsiblings at university." Derek said finally, softly. "We were Derek and Casey. Derek and Casey only. No strings."

George knows what he means, but he pretends he doesn't.

"It's been years." George said, after searching for something to make it better. "The two of you can be mature about it, can't you?"

Derek stands still, looking at his feet.

"You're not over it?" George asks, trying to fill in the piece that he's still missing without actually finding out more information. "It's been three years!"

"They don't have to see each other." Sam interjects. "They've done it before, they'll manage again."

"You have to go the wedding, Derek. Nora will expect it. You'll just have to get over it."

Silence. Sam tried again, but Derek and George ignore him.

"It's been years, Derek." George had run out things to say, so he kept repeating his best argument.

"I didn't know there was a statute of limitations on being upset over a rejected proposal." Derek snaps, and then walks out the front door.

George turns to Sam. "Did he-" but he can't finish the sentence. It's too messed up. Too wrong.

"Yes." Sam says. There's a pause. "If she had said yes, would you and Nora have come around to it? They were really happy."

"No." George says curtly. "No, we wouldn't have."

He walks out the front door too.

---

It's Sam who convinced him he had to go her wedding. She's been back six months, and they've spoken twice, but only because he's had to. They both played it cool. She tells Jamie that Derek is a jerk, and they never got along. Derek plays into that roll, making snide comments under his breath and sending glares at Casey.

George kicks him under the table.

It's uncomfortable, and Jamie surely knows there's more to the story. He doesn't say anything though.

She has the fucking audacity to send him (and Sam, since they live together) a wedding invitation. Jamie obviously gave Casey the reigns on wedding decorations because it was pink and frilly.

He wouldn't have let her pick out something pink and frilly.

Except he totally would have, because he wouldn't have cared what the invitations looked like or the wedding decorations or any of it. He would just have been happy to be with her.

They choose the cheesiest banquet hall, Derek thinks. It's cliche and overdone.

They would have picked something different. Unique.

She asks Lizzie, Marti, Emily, Natalie, and Sarah to be bridesmaids.

They would have done the same, with Edwin, Sam, Brett, Eric, and Tyler as groomsmen.

If they even had a traditional wedding. He always imagined them having a destination wedding or simply just eloping and being done with it.

He wonders what Casey is going to tell Natalie and Sarah when they see him there. Maybe she's hoping that she won't come so she can avoid it all.

Maybe it's spite or maybe it's just them, but he can't make it that easy for her.

If she marries that guy, she going to have to do it despite the obstacles. She'll have to explain away the ex-boyfriend whose also her stepbrother. He revels in the fact that Jamie will definitely find out.

It's perverse and spiteful and probably just mean spirited. Derek can't imagine Jamie wanting to marry Casey after finding out. It's the whole reason they ended their relationship, the taboo of it all, but it works for him in this instance, so Derek's going with it. To hell with the fucking irony.

---

She's only invited three people from college to her wedding: Brett, Natalie, and Sarah. Brett already knows, so it's all good there, but she has no idea what Sarah and Natalie will do, when they find out.

Maybe he won't come. She's actually banking on it. It'd be just like him, to run like a coward. That's what she tells herself at least, because it's actually just like him to show up just to spite her.

She waits until the last possible minute. She worries they'll back out when they find out. She feels guilt when they buy their dresses and book their hotel rooms. Jamie picks up on it, because he can read her better than anyone else, but he doesn't understand why she feels guilty, just that she does.

Jamie doesn't like Derek. She can tell by the way Jamie's eyes follow Derek around, and how his voice rises - just an octave higher - when he speaks to him or about him.

Her family can tell too. They look away or at each other when Derek and Jamie speak. It only happens a few times, but it's certainly memorable each time. Derek is nasty and Jamie is just a touch too rough. It's uncomfortable. George won't meet her eyes, and she can't understand why, but deep down she knows it's because he knows about her and Derek.

Casey knows that Jamie knows, or at least suspects.

Derek makes sure to be at his parents' house, as they get ready for Casey's bachelorette party, three days before the wedding. Lizzie does everything in her power to shoo him out, but it doesn't work. Derek is too stubborn.

Sarah walks in with Natalie, and they both freeze when they see Derek perched on the couch, with an extremely peculiar look on his face. It's a mix between smugness and hurt.

"Hey D." Natalie says, breaking the ice. Her voice is soft, but it's loaded with implications.

"Hey Nat. Hey Sarah." Derek grins at them, but it maniacal. Neither girl is sure what to say for half a beat. Casey walking in prevents them from taking action, whatever that might be.

"Oh, hi sis." Derek says cheerily when he sees Casey. His grin is dangerous.

"Sis?" Sarah asks, her voice several octaves too high.

Casey is dressed to the nines, black jeans and sparkly top with her makeup done up. She glares at Derek because of course he would. Natalie and Sarah turn to Casey for confirmation.

"I'm sorry," Derek says, though he feels a twinge of guilt. Natalie and Sarah are his friends too. "Did we never mention that before?"

"Derek." Lizzie warns. She might kind of know, but she doesn't actually know and she's certain she doesn't really want to. It'd ruin something, or was it everything?

"What?" Natalie asks, again looking only at Casey.

"If you don't believe me, look at this." He's holding a family picture out for them to see. If they had time to process everything, they'd have noticed that the family room featured photos of six children, Casey and Derek both included.

"Step-siblings." Casey says quickly. "Look, guys, I can explain."

"Explain what?" Marti asks, confused.

"Go to your room." Lizzie says, practically pushing her up the stairs. "Now."

"That's not fair!" Marti screams, and Derek feels incredibly guilty now that Marti is involved. He's determined, however, to see this thing through. Damn the consequences. He would have told them when they were dating if Casey would have allowed them to. Now he'll tell them to fuck her over. He's always loved Casey and he's so fucking tired of pretending that he doesn't.

"Please." Sarah says low. "Someone explain something."

"We met when we were fifteen." Casey says, facing her best friends. Somewhere in the mix Emily arrives, though she isn't wholly surprised by any of it. "We didn't lie about that. We met before we knew who the other person was. It was... whatever it was at first sight."

"Love," Derek says, his voice the opposite of loving. "Love at first sight."

Casey glances at him for half a second, her breath hitching despite herself. She ignores it and moves on. "Fine. It was love at first sight." She concedes. It's true, so no point in denying it. "But we couldn't let anything happen, for obvious reasons. So, we fought throughout high school and ignored what we wanted. When we went away for university, Derek introduced me as someone he knew from high school, and it was kind of like a fresh start. We still fought it. You remember, it took years and lots alcohol to convince us to be together."

"What!?" Marti asks, staring at Derek.

"Go upstairs, Smarti. We will talk later." Derek says, but his voice is soft.

"I don't think I will." Marti says, walking over to Lizzie, who automatically opens her arms to her. "I think I need you to explain, too."

Its Derek who speaks this time because its Marti who is asking and he didn't think this through. "Casey and I were together, for two years at university. We broke up before she went to New York."

Lizzie inhales sharply. She was right. Kind of knowing and actually knowing is super different. Marti just stares at them because what. the. actual. fuck.

Derek's grin turns menacing again. "Casey knew the entire time, of course, that our relationship was doomed to end. She didn't tell me that, though. She let us date - and even live together. I thought, after we'd graduate that we'd tell everyone. It'd be awkward, sure, but you'd come to understand, with time. She knew the entire time, so the point is moot."

"I need to sit down." Natalie says. Sarah nods in agreement.

"I should have told you two." Casey said, looking at Natalie and Sarah. She turns to Emily. "You too, Em."

"Eh." Emily says. "I think I always knew, deep down."

It's as accepting as she's going to get, so Casey accepts it. "I understand if you don't want to be in the wedding anymore." Casey says. She's talking specifically to Natalie and Sarah, but honestly, it's an open invitation to the five women in front of her.

"I think we should go." Sarah says. Natalie follows her, throwing a look at Casey.

Derek grins evilly.

"I hope your proud of yourself!" Casey screeches, running out of the house.

Lizzie follows immediately. Marti hesitates, then turns to Derek. "You are proud of yourself, aren't you?"

"Kind of." Derek says with a smug look.

"Fuck you." She says, and Derek does a double take. He didn't know that Marti swore. "You say you loved Casey, but this isn't love. Its petty and cruel. I'm sorry that this is the hand you were dealt; it's not fair, but some of us have to deal with much worse."

"Marti..."

"For the first time in my life, Derek Venturi, I'm disgusted to be your sister." She slams the door as she follows Casey and Lizzie.

Emily stays for a minute to glare at Derek. "You knew the risk, when you dated her in the first place." She's all hard edges. It's protective Emily, and it still scares him. "Shame on you."

She walks out, too.

---

Lizzie and Marti come home late smelling of alcohol, after Derek has already left. George had waits up, and when he sees the girls, he guesses.

"Derek spilled the beans?" He asked.

"Yeah." Marti says shortly. "Casey is a mess."

"The whole thing is a mess." Lizzie says. "She's thinking off calling off the wedding."

George groans. If she calls of the wedding, then Derek and Casey might get back together. Nora would find out then, and he was sure it would break her heart.

"Not a word of this to your mom, Edwin, or Simon." George warns. "Off to bed. Now."

Then he goes off in search of Derek.

He doesn't find him.

Casey had rented a hotel room. Jamie had a big work presentation the next day, and she wanted to be considerate.

Emily, Marti, and Lizzie stay with her most of the night. They drink too much, even Marti. Casey allows it under protest. She's not in her right state of mind. Emily makes Lizzie take Marti home before it gets too bad, and for that Casey is grateful.

Emily stays with her. Around three in the morning there's a knock on the door. Emily opens it, to find an equally drunk Derek. "Case, it's for you."

She leaves because whatever is about to happen is beyond her, but she sends a glare at Derek on her way out.

"What are you doing here?" Casey asks as Derek barges in.

"Don't marry him!" Derek exclaims.

"Derek..."

"No, don't 'Derek' me. Don't marry him, Casey. I get it now, why you couldn't marry me. Honestly, I do. Just don't marry him." His voice cracks and so does Casey's heart.

She starts to respond but he cuts her off with his lips.

She pushes him off, but then she meets his eyes, and she melts. She's too drunk for this, and suddenly she's kissing him again.

They spend the rest of the night making love. Casey knows it's wrong, for so many reasons, but his lips are on hers and she's missed him so much.

"What does this mean?" Casey asked, with her head on Derek's chest as they watch the sun rise from the window of her hotel room.

"What do you want it to mean, Casey?" He asks. "It's always been up to you. Don't pretend like you don't know that."

He doesn't sound too bitter; they've spent the entire night making love, kissing and touching the damage away. But the ball has always been her in her court, so to speak, and he won't pretend otherwise. He was the one who always pushed too far, and she was the one that always pulled away.

"I should talk to Jamie." She sighs. "You're right. I can't marry him."

It's pure joy, hearing her say that. Even if they aren't together, at least she won't marry him.

"And us?" He asks because he can't help it. He still a little drunk, so he ignores all the damage that may or may not irreparable.

"The whole family knows by now, I'm sure." She says. "We'll deal with the fallout together."

He grins because together is what he wants to hear.

It truly unfortunate when the pair - naked and wrapped around each other - are awoken to the sight of Nora and Jamie. Casey hadn't responded to any of Jamie's texts the night before, and when he finds out none of the girls spent the night with Casey, he's worried enough to get Nora involved.

Jamie grits his teeth and glares at Derek. Casey's suspicions are confirmed: he did know all along.

Nora shrieks and swears. She's completely blindsided; she hadn't even realized that this was even a possibility.

"Mom. Just hold on." Casey begs as she clutches the sheet to her naked body.

Nora, still Casey's mom, throws her a shirt (Derek's, but she doesn't notice) and Casey slips into it. She picks her underwear off the floor, sliding them up her legs and throws Derek his boxers.

"Just give me a minute, mom." She begs, running after Jamie, who is almost out the door.

"Wait, Jamie." Casey cried.

"Why?" He asked, his voice bitter.

"I'm sorry." Her voice is small. "I don't expect you to understand, but I'm so, so sorry."

"Is that supposed to make it okay?" He demands. "That you cheated on me by fucking your brother? Sorry, stepbrother."

Derek realized she's made that correction to him before. It's a small detail, but it matters.

She looks down at the floor. Derek, still in his boxers, stands up, ready to intervene if necessary. Nora watches in horror.

"It's okay, Case." He says softly. "You told me, on our third date. You were honest, I'll give you that. You told me you'd never get over your ex. It didn't matter then. It probably should have."

She doesn't say anything. Nora looks at Derek and mouths "ex" to him. He shrugs. They can explain later.

"It never occurred to me that it was your stepbrother. Not until I met him. I knew then."

"I'm sorry." Her voice breaks. "You never been anything but perfect. You don't deserve this."

"No. I don't." He shakes his head. "We never should have come here, Case. I knew it, but I let you talk me in to it."

"We have a few things to work out. The mortgage and what not." Jamie said. "We'll talk. Not for a few days, but we'll talk."

Jamie leaves. Casey shuts the door behind and turns to face her mother.

"Do I want to know?" Nora asks, her voice faint.

"Nora." Derek says. He's put on pants, but he's shirtless, as Casey is wearing his shirt. "It's not as bad as you think."

"So, you two didn't sleep together then?" Her voice is pure venom.

"Mom." Casey tried, but Nora holds up her finger.

"Jamie said ex. Is Derek your ex, Casey?"

"Yes." Derek answers.

"How long?" Nora asks, her voice rough and dangerous.

"Two years." Casey says, looking at the floor.

Derek kind of gets it now, as he watches Nora process, why Casey did what she did.

"When?" Nora demands, voice the same.

"Right before our sophomore year ended all the way up until a few weeks before I graduated university." Casey responds.

Nora looks at both of them for a second. "I can't do this." She walks to the door but turns right before she leaves.

"Of all the terrible things the two of you have done, I won't forgive this. I can't."

---

They aren't together because nothing's changed. If anything, their family knowing has made it too real. They still spend the night together a few times a week though. They don't talk; there's really nothing to say.

Brett - who was staying with Sam and Derek for the wedding - helps Casey call off the wedding. Sarah and Natalie go home, telling Casey it's just too much. Jamie puts their house on the market. It sells quickly, but they don't really make a profit, as they've only lived there a few months.

Casey was right; she'd been right all along. George and Nora don't understand. They probably never will. Derek supposed she should have known; Casey is always right. He's learned that the hard way.

Sam smirks at Casey when she lets herself in to his and Derek's apartment for the fourth night in a row. She rolls her eyes at him. There's no real need for an explanation at this point.

"He's not home," Sam calls when her hand reached the doorknob of Derek's room. "You can wait there if you want. Or you can come have pizza with me."

She finds herself sitting on Derek and Sam's couch, on her second slice of pizza, laughing at an episode of Friends, when Derek walks in. He freezes for half a second, before grabbing a slice and joining her on the couch. Three minutes in his arms settle around her shoulders. Even though they've been sleeping together for weeks, this feels like the most intimate thing they've done in a long time.

They fall into a new dynamic. It's a weird state of not-dating-but-kind-of-really-dating.

They're not dating. There's too much damage, most of it irreparable. They haven't talked about any of it.

Yet Casey spends her free time in Derek and Sam's apartment. She makes dinner, watches tv with them, and sleeps in Derek's bed. She has a drawer in Derek's room and a shelf in their bathroom.

Nora doesn't answer Casey's calls. George answers Derek's, but all he does is yell. Marti and Lizzie get over the shock after a while. Edwin still doesn't know. Derek wonders if he should tell him. Secretly he thinks Edwin would be the most upset, either because he's the last to know or because Casey has been Edwin's sister for close to ten years. Somehow he feels like Edwin knowing about Casey and Derek would cheapen the sibling relationship formed by Casey and Edwin.

The most messed up part, Derek's the happiest he's been in a long time. He likes having Casey back, even if it isn't exactly how he wanted. Every moment he spends with her feels like a gift.

They don't talk about what happened. George and Nora's reactions prove that Casey had been right all along. He doesn't let himself think too hard in that vein; the difference between him and Casey is that he'd have chosen her over the family, and she clearly chose their family.

He doesn't blame her. Really, he doesn't. He even understands it. Her way was sensible, practical. His way was selfish. It's true to who they both are, and completely unsurprising.

Two months after Casey called off the wedding, Casey's apartment floods. Or rather, the old lady living above her floods her bathroom, and it all leaks down to Casey's apartment. It's a horrible one studio apartment that Casey can barely afford on her starting law job. Half her stuff is destroyed. She dials Nora first on instinct.

Nora doesn't respond.

She ends up calling Derek, who picks her and helps her pack up what isn't ruined. She's released from her lease and ends up moving in with Derek.

They're not dating. They can't be dating. Everything is just too broken.

Yet they share a bed and cook meals together. They joke around with Sam, as they eat the meal they cooked sitting at the kitchen table. When dinners over, Sam insists on doing the dishes, and Casey dries. They all watch TV together, before Casey goes to bed, stating she has an early morning the next day. Derek follows her into their shared bedroom.

They're not dating. Except they totally are.

Derek blurts it out on evening, as they're laying in bed watching The Office reruns. "What are we doing, Case?"

She freezes for half a second and then shrugs too causally. "We're watching tv."

"Casey!" Derek groans. "What are we doing together."

"Derek, we can't go down this road?" Casey begs.

"Or what? Our parents will find out? Nora will stop speaking to you? My dad will be angry and disappointed? I hate to burst your bubble but we're already living with the consequences."

She blinks. He's right, yet openly dating Derek still feel inherently wrong. It's been ingrained for so long. She tells him as much, and he laughs.

"I was thinking something a little more permanent than dating." Derek pauses. "But this will be the last time I ask, so I need to know that you won't say no again."

Her breath catches. "How would that work?"

It's not a "no," at least not yet, and Derek's stomach fills with hope.

"We'd move to Kitchener or somewhere that's not close, but not too far. George and Nora may not approve, but Marti, Lizzie, Sam, and Emily seem fine with us. Edwin still doesn't know, but he's always looked up to us. He'd come around."

She tilts her head and waits for more.

"We'd start fresh in a new city. We don't have to move immediately. We can start applying to jobs and figure it out from there. We'll find an apartment - bigger than our last - but within our price range. I'll work my way up to university level coaching and you'll work your way up in the law firm of your choosing, and then we'll buy a house. We'll be close enough that any family that wants to can visit can. Maybe Marti can even go to school in Kitchener."

"What about Simon? We'll miss his entire childhood?" Casey asks.

"Unless something changes, that's already a high probability." Derek's voice is soft with regret. He hates it as much as she does. For a while, he resented Simon, because Simon was just another one of many reasons why they couldn't work. It's hard to resent a baby, however, especially one as cute as Simon. It only took meeting Simon to realize that he could never truly resent his little brother. Derek just loved him too much.

"And when we get into a fight? Or you realize you're still angry with me?"

"I'm not." Derek says plainly. "I get it now. You were always right. We lost George and Nora. They don't understand."

She knows she should say no. She knows it down to her very core. But it took years to heal (if she ever really healed) from their first break up. Living without Derek was fine. She was even happy for a while. Yet there was a piece that always felt like it was missing. Life with Derek was so much for fulfilling.

"And if we fight?" She repeated, though he could tell her argument was fading.

"Making up is the best part." He said, his voice low, as he bent to kiss her neck.

"We'll lose a big part of our family." She says with one last attempt to do what she knows is right.

"We'll start a new one." He murmurs before catching her lips.

---

They get married at city hall. It turns out that Marti and Lizzie do understand and while they certainly are a little hesitant, they both attend the wedding.

Edwin doesn't take the news well. He can't fathom how he missed all of it, or how they kept it a secret for so long. He tells them he's not coming to the wedding. Derek understands but it does break his heart, just a little bit.

Casey calls Edwin before they leave for City Hall. She reminds him of the address and time, just in case. She tells him that she won't hold it against him if he doesn't show, but it'd mean the world to both of them if he does.

Edwin bursts in - in Derek's old hockey jersey and jeans - right before they say, "I do."

They all go to dinner afterward. It's not big or spectacular or anything Casey imagined her wedding reception would be. It's still perfect. Casey can't imagine ever being happier. It's exactly as Derek imagined, and he swears he'll never forget a moment of this day.

She holds back the tears that Nora and George didn't come - they'd sent an invite, which was completely ignored - until Derek and Casey are alone. He holds her as she cries and tells her it's going to be okay. He doesn't cry, and he's certainly not surprised, but it's hard for him to shake the hole in his heart as well.

They move two months later, and they forge the life that Derek described. It's Casey and Derek, so it's messy and filled with fights, drama, laughter, and several scrapes. It's absolutely wonderful.

Three years later, Casey is seven months pregnant and has long since given up on forgiveness from Nora and George, when Derek takes a sick day, and drives back to London. George answers the door, a frown immediately taking shape on his face when he sees Derek.

"Is Casey okay?" George asks.

"She's more than okay. She's perfect. Seven months pregnant, in fact." Derek says, still standing in the doorway.

"I won't stay long." Derek says. "I just thought you should know. We'd love if you were a part of Luca's life."

George calls for Nora, and Derek can hear the floorboards creaking as she makes her way downstairs.

"It's a boy?" George asks. He's not sure if he should be happy or mad, though he supposes he's not super surprised. They've been married for a few years, and although he's never asked, the kids keep him informed.

He's still mad, but he misses them both.

"Casey's pregnant?" Nora asks, as tears form in her eyes.

"Yes." Derek says and he can't stop the grin from finding its way on his face because this is everything to him.

"Casey didn't even tell me." Nora blinks rapidly.

"You haven't spoken to her in three and a half years, Nora." Derek admonishes. "She thought it'd hurt worse if you knew and didn't care."

"Of course I care!" Nora snapped. "But what the two of you did is wrong. That just doesn't go away."

"It could," Derek says as he shrugs away George's offer to take his coat. "She's afraid of being rejected again. I know she'd love to hear from you."

"All the damage won't just magically go away." Nora snaps.

"No," Derek agrees. "Though I'd imagine it'd be a lot easier to swallow while playing with your grandchild." He turns to leave. "Just think about it."

---

Casey loses the baby three weeks later, and is forced to see the delivery through. Derek calls George because Casey needs Nora right now. He needs his father if he's being honest.

George answers on the third ring. It's two in the morning, and when he sees Derek's name on the caller ID, his heart stops. Derek can barely get the words out, but he doesn't really need to. George nudges Nora awake.

It's the longest two-hour drive of Nora and George's life. Simon sleeps in the backseat, completely unaware of what's happening.

Derek's not truly convinced that they're actually coming until he sees them in the flesh. He hadn't told Casey, just in case. He didn't think she could handle any more pain.

Casey sobs in her mother's arms, and Derek wishes he could do anything to make it better. The nurse recommends a therapist, and when Casey is discharged they all head back to Casey and Derek's home. George, Nora, and Simon stay for a week, and Casey slowly becomes more and more functionable.

Nothing has changed. The relationship better Derek, Casey, George, and Nora is still bent and broken, yet the damage wanes in the wake of their shared grief.

Nora calls Casey once a week once they return home, and then they start to rebuild their relationship. Time heals for Casey and Derek. They do end up going to see the therapist that the nurse had recommended. It helps quite a bit.

A year passes before Casey and Derek make the decision to try again. This time feels right, because Casey calls Nora when she has morning sickness, and Nora tells her all about her three pregnancies.

George and Nora visit a few times. Casey is excited to see Simon, and the trip focuses primarily on the new baby and Simon: George helps Derek paint the nursery and Casey takes Simon shopping for sports gear (he picks everything out, mostly from Derek's suggestions and Casey pays). They go for ice cream and to the movies.

They don't talk about the elephant in the room. It's just easier that way.

They drive up with Edwin, Lizzie, Marti, and Simon when Casey goes into labor. Nora cries tears of joy when Casey delivers a healthy baby girl. They name her Tara.

The family starts to rebuild. It's filled with missteps and fights (it always will be), and they'll never be the same, but they're whole again, and that does feel right.

Nora and Casey's relationship centers mostly around Tara, which is perfectly fine with Casey. Derek and George simply never address the fact that Derek and Casey are stepsiblings. Their siblings don't really care too much in the end. Derek and Casey had always been linked in their heads, and this makes much more sense than their messy love-hate relationship.

Everything about Derek and Casey's relationship was chaotic from the start, and they're sure it'll remain that way for their rest of their lives. Tara proves to be the best thing Casey and Derek have ever been a part of. She brings out the very best in them, as neither of them can be selfish when it's comes to her.

For the first time in a long time, Casey feels whole.

---

AN: So there it is. Almost 30,000 words dedicated to Dasey. I hope you enjoyed it!

I hope this wasn't too dramatic, but I wanted to provide a more realistic point of view. I dont think Nora and George could just be fine with Derek and Casey. I also wanted their life together to be way less "Disney." I wanted it to feel more real.

Leave a review - I'd love to hear your thoughts!

Thank you so much for reading!