Life with Derek was never easy, but it had been manageable, up until Derek and Casey's junior year of college.

Their parents decided that since they were attending the same university, that they should share an apartment. It was a logical conclusion, even though they still fought like they did in high school. They tried to talk them out of it, but Nora and George were adamant. So, Derek and Casey did the next best thing: they tried to avoid each other like the plague. Their schedules were vastly different; Derek was taking film classes and photography courses, when he wasn't busy with hockey, while Casey was pursuing English Lit and socializing with her new study group.

Their avoidance plan almost worked. That is, until they were left alone in the apartment together for the first time since they moved in, about six months after they started college. But, instead of killing each other, it was… comfortable. Somehow, the need to bicker wasn't as strong without their family members there. Of course, that didn't mean it stopped completely; Derek and Casey were far to Derek and Casey for that. But, they hung out more. It wasn't like they were best friends or anything, but they were closer than they had ever been.

Until that night.

It was a night Casey's study group decided to break early, so she was hanging out at the apartment, after making sure Derek would be with his hockey buddies, of course. She was going to spend the night in, watching A Walk To Remember and munching on popcorn. That's how her night was supposed to go.

Just as Jamie was taking Landon to the orphanage, Derek stumbled inside, laughing. "Yeah, whatever, Sammy-boy," he chuckled, rolling his eyes and shutting the door. He eyed Casey on the couch, a frown playing on his lips. "What are you doing here? Aren't you supposed to be at the library or something, Space-Case?"

Casey scowled. What, are you keeping track of my schedule now? "Aren't you supposed to be with your lame friends and your horde of fan girls?"

Derek smirked, plopping down next to Casey on the sofa, stretching out. "Move over," he complained, nudging Casey so he could take over half of the couch.

"No! I was here first. You move." Derek whined, and Casey wrinkled her nose. "Have you been drinking?" His breath smelled like Jack and Coke.

"That's not the problem, Case. Now, scoot!" Derek insisted, shoving Casey lightly.

"Der-ek!" Casey remained where she was. He is not going to ruin my night!

Derek didn't seem to see this as a problem. He just smirked once more, and settled for laying his head in Casey's, feet dangling over the arm of the sofa. "Hey, this works too."

Casey looked down at the cocky head in her lap, stunned. "Aren't you- aren't you uncomfortable?"

Derek wiggled around a bit, his expression contemplative. After a few minutes, he stilled, turning his face towards Casey's stomach and closing his eyes. "Nah, I think I'm good. Besides, what are sisters for, right?"

"Step," Casey muttered, cringing. She couldn't believe she had just said that. What did it matter if he thought of me like his sister? But it mattered to her. More than she was willing to admit.

"Hm?" Derek murmured, his warm breath tickling Casey's stomach through her camisole. "Oh, that's right. What are step-sisters for. Thanks for the correction, Princess."

Casey swallowed, willing herself to focus on the movie. "Can't you go pass out in your room?" She asked, exasperated, unable to pay attention to Mandy Moore.

"Quit talking, I'm trying to sleep," Derek mumbled. He scowled, his eyes still closed. His arms somehow managed to snake themselves around Casey's waist, and he was… Derek was nuzzling her. "M'room doesn't have you. You're comfy, Casey." He giggled softly. "Comfy Casey."

Casey wasn't sure how to process that, so she just stared blankly at the television screen. A few minutes passed, and she could feel Derek start to get restless. "I thought you were sleepy," Casey muttered, frowning at him.

And then Derek did something that shocked her. He smiled, fingers ghosting over Casey's hips, over her shirt, then under her shirt. Casey gulped, frozen, while Derek chuckled and pressed light kisses over her newly-exposed abdomen. "D-derek… What are you doing?"

This seemed to give him pause. "Do you want me to stop?" He whispered, lips half an inch away from Casey's navel, and he looked up at her with an expression she couldn't recognize.

"No," Casey said quietly, and Derek grinned. He sat up slowly, a little wobbly, and pulled her into his lap carefully. "Is this okay?" He murmured, staring into Casey's eyes.

Casey couldn't speak, so she just nodded dumbly. On some level, Casey had wanted this since they were fifteen and screaming at each other. All of the tension between them, all of the sexual tension… it finally led up to this, and Casey couldn't bring herself to tell Derek to stop. So he didn't.

"I've wanted this for so long," Derek whispered, and then he was leaning in, and his lips were on Casey's. Their first kiss was hesitant and sweet. His lips brushed over Casey's, and he sighed, leaning their foreheads together. "I knew it would be like this. Perfect." He grinned against her lips, and suddenly he was kissing her with a fervor that was well matched. It turned from sweet to sloppy and wet, but it felt so good, and it was Derek. His hands were everywhere, and she explored his chest, yanking the fabric of his t-shirt up.

Casey tried to stifle a moan when Derek's lips moved to her neck and bit, but he wasn't having that. "I want to hear you, baby," he rumbled in a rough voice, and she could hear the smirk. He bit again, and Casey couldn't help herself; it felt good, and she hadn't done this for so long.

"Derek," Casey breathed, grabbing a fistful of his hair. His lips traveled down her neck and he groaned softly.

"Too many clothes," he muttered, pushing my shirt up and reveling at the newly exposed skin. "Oh, sweetheart, you're beautiful." Derek nuzzled Casey's breasts, his tongue tracing patterns on the delicate skin. His nimble fingers tugged lightly on the straps of her bra, hesitant, like he was asking a question.

Casey gazed into those brown eyes, a blissful smile on her lips. "It's okay," she murmured, watching his face as she slowly unhooked her bra and tossed it off. "I want this."

Derek was amazed. "Who knew you'd be such a firecracker, Princess?"

Ω

Casey woke the next morning to an empty bed.

"Derek?" She called hesitantly, padding through their apartment in search of her lover. It was nine in the morning on a Saturday; in theory, Derek should still be sleeping, but both beds, hers and his, were empty.

Casey received no answer to her calls, and in the kitchen, she found a note slapped onto the refrigerator.

Impromptu hockey practice. After, I'm going out with the guys. Don't know when I'll be home; probably late. Don't wait up. – D

Ω

The next few weeks, Casey saw even less of Derek than she had the first few months they lived together. He seemed to have memorized her schedule so he could avoid her. Even during the times they were both free, Derek either was out or had his friends over. At first, it seemed as though they could just forget the incident. Casey tried to accept that and move on.

But after a few months, she knew it would be impossible. She couldn't take it; they needed to talk about what happened, and if Derek thought avoiding her would make the issue go away, well, he was wrong.

So, Casey skipped her study group on a day she knew Derek didn't have practice. She crept into the apartment, hoping Derek wouldn't hear her until it was too late.

Taking a deep breath, she knocked on Derek's closed door. There was a muffled curse and the door yanked open, revealing Derek, shirtless and with serious bedhead. "What the fuck are you doing here?" he stammered, with none of his usual cockiness.

"I skipped," Casey explained, shoving past Derek into his room. Derek moved back dumbly, a shocked expression on his face. "We need to talk about what happened, Derek."

This seemed to snap Derek back into consciousness. "No, we don't," he spat, jaw tightening. "We can just pretend it never happened. It shouldn't have happened."

"Regardless of whether it should have or not, it did. And we need to discuss it."

Derek snapped. "We don't need to talk about it, Casey, dammit! I was drunk and you were there." He smirked. "More than willing, too, if I remember correctly." Casey looked as though she had been punched in the stomach, and Derek added quietly, "Look, I was trying to make it easier for you by not being around, but you just had to have this talk… So, yeah, it happened, but it was a mistake. We both just need to go back to our regular lives and forget this ever happened."

Casey's heart broke that night, and she was fighting tears as she filled out her transfer sheet.

Ω

Casey transferred to University of Toronto after the semester ended without warning. She finalized her arrangements, packed up her belongings a few days later while Derek was gone, and left. It was too harrowing to remain in her old apartment any longer.

So, she immersed herself in her classes. Casey was so focused on her schoolwork that it took her two weeks to realize that the weird feeling she got in her Lit class was someone staring at her. A very familiar someone.

"Sam?"

A slow grin lit up Sam Richards' features, and he pulled Casey into a tight hug. "Case! It's great to see you. But, I mean, weren't you at Queen's with Derek?"

Casey seemed to shrink into herself, a shattered expression on her face. "I was, yeah. But I decided I liked Toronto better."

Sam threw an arm around his ex-girlfriend, rubbing her shoulders comfortingly. "Don't worry, Casey. It'll be okay. Do you want to talk about it?"

Casey was so tired. She blamed the exhaustion and seeing a familiar face for her quickness to spill her secrets to Sam. So, three hours and many tears later, they found themselves in Casey's small apartment while Sam tried to comprehend.

"I can't believe Derek would do that to you, Case," he mumbled, pulling her into his arms. "Do you want me to call him?"

Casey paled. "No! You can't, Sam… There's – I mean, I haven't… You don't know everything," she stressed, gripping Sam's wrist tightly. He looked at her expectantly, and she sighed. "Sam, can't you just trust me?"

"Unless there's a really freaking good reason, Casey, I'm calling Derek and chewing him out. He had no reason to treat you like that," Sam said firmly, eyes locked on Casey's.

Casey closed her eyes, her heart pounding in her chest. Her hands dropped protectively to her stomach. "Sam," she began softly, looking up at him through lowered lashes. Her breath hitched in her throat, and she whispered, "I'm pregnant."