I gaze at myself in the mirror. I don't recognize the person staring back me. She's reminding me of that Britney Spears song, I'm Not a Girl, Not Yet a Woman.

While I'm legally an adult, I can't help but feel like a little girl playing dress up, trying to muster up an Academy Award performance for most devoted girlfriend. The old Casey would never put on a smoky eye and sinful red dress. I close my eyes and count to ten, taking a calming breath because I can feel the panic setting in.

I feel exposed. Naked even.

My breasts are on full display, pushed up, creating more cleavage than I would have guessed I was capable of having. The thin straps on my shoulders do little to ease my anxiety at the real possibility of exposing myself to the students of Queen's University. The keyhole aspect of the dress somewhat exposes my flat stomach, while the hem only comes to mid-thigh if I'm lucky. I have a feeling I'm going to be tugging it down all night.

I pick up my cell phone and I'm momentarily tempted to call Emily. I need girl advice more now than ever before. But if I call her, I'll have to explain everything. I'm not that good of a liar. That's why I've been avoiding everyone like the plague; my mom, Emily, and even Lizzie. Especially Lizzie after my stupid phone call the other night. I blame the wine.

A heavy knock sounds on the bedroom door, startling me. I nearly drop my phone. I sit my cell back down and make a conscious effort to ensure that my voice doesn't shake. I haven't talked to Derek since this morning. Not since our shared outburst and the way he looked at me when he told me he'd been in love, but not with Sally. I've been trying to think about anything else but that conversation; why the sky was blue, the square root of pi, how long I'd be able to hold my breath while standing on my head?

I may have actually tried that last one after class let out today. After ninety seconds, I was on the verge of passing out. I would have welcomed the oblivion.

"Yeah?" I finally speak.

"It's eight-thirty. Are you ready yet?"

Derek's voice is surprisingly calm. I can tell he's as nervous about tonight as I am. I pick up my pink lip gloss and quickly apply it before opening the dresser and rummaging around for the pink bikini tucked in the back. I should leave it behind, but peer pressure was a harsh mistress. If I didn't bring it, I'd be forced to wear only my bra and panties, which was so not happening. I wad up the small fabric and tuck it into my purse before sitting on the edge of the bed and putting on my silver heels, making sure the strap around my ankle is secure. The last thing I need is to fall flat on my face and add to the humiliation.

I stand up, taking one last look at my unrecognizable self in the mirror, and finally admit to myself that I'm not completely unfortunate looking. I'm actually pretty in a conventional sort of way, but that does little to ease my trepidation. I don't want to open the door and have Derek look at me the way I am now. But if I can't even let Derek see me half naked, in the dress I'm wearing solely for him, how am I going to walk into a packed party this way?

I reach out to unlock the door, slowly pulling it open.

It's now or never.

My own breath catches at the sight of Derek. I haven't seen him all day. We've been avoiding one another, and I'm suddenly shocked to realize I actually missed the jerk.

His hair is still wet from his shower, falling over one eye and curling at the nap of his neck. He has on a nice pair of jeans and a tight white t-shirt that shows off his newly acquired muscles and taunt stomach. But it's his deep rich chocolate eyes that are currently drinking me in that really catches my attention. He's skimming his gaze all over my body, not missing an inch. And while I feel self-conscious, I know the thoughts that are swirling around in his head. I may be inexperienced when it comes to sex, but the desire behind his eyes is unmistakable.

"Case," he says my name in a husky whisper. His arms are crossed as he leans against the door frame for support. "You look…"

"Ridiculous?"

"Fucking incredible."

His brazen compliment catches me off guard. I laugh nervously and on instinct, fold my arms over my chest to hide myself from his gaze once it becomes apparent that he no intention of glancing elsewhere.

"We better get going. Wouldn't want to be late for our performance of the century," I say casually like his intense stare doesn't have a major effect on me. I brush past Derek. But I don't get far.

He catches me by the elbow, and I stumble. I fall into him. His warm hard body is pressed up against my back. His hot breath tickles my ear when he speaks. Normally, I'd yell at him for manhandling me and give a speech about boundaries, but I'd be lying if I said it didn't somewhat excite me. The few times I've had boyfriends, they would ask permission to kiss me or would hold my hand innocently. Not once did they press me up against them with force.

They were respectful, yet boring. The complete opposite of everything Derek was.

Derek's always been forceful with me, and while I'd kick and scream, I didn't mind it. Not as much as everyone thought I did. He had a tendency to get a bit rough at times, but not once did he intentionally hurt me on a physical level. Even when he would pick me up and toss me to the side, nine times out of ten, he made sure there was a soft landing nearby.

"The last thing I should do is let you out looking like this. I wonder how many fights I'm going to get into tonight. I'm not even allowed to get drunk enough to not care."

"We…we could stay home," I stammer, cursing myself for the way I'm shaking. I'm secretly hoping he agrees.

The humor in Derek's voice is evident when he bends down even further, his lips against my ear when he whispers, "It's a lot more dangerous here than it is at some party, Princess."

I can officially hear the pounding of blood in my ears. I instinctively close my eyes and press my back more firmly against his solid chest, and for a moment, I feel completely safe despite the threatening words coming from my step-brother's lips.

Sixteen-year-old me would have freaked out if Derek had threatened sex.

Eighteen-year-old me is trying desperately not to turn around in his arms and crash my lips to his.

My flesh is on fire as Derek's skin, slightly rougher than my own, gently wraps around my wrists to put them down at my sides. His thumbs are working in circles, and while he doesn't place a kiss on my neck, I can feel his soft lips against the tender spot.

"Don't ever cover yourself again. You're perfect. Own it."

And just like that, the warmth of Derek's body is gone as he walks around me and down the hall. I open my eyes in a daze, disappoint flooding me.

I shouldn't play with Casey that way. That sort of game is far too dangerous.

I was expecting her to elbow me in the ribs. I was waiting for her to tell me to get my hands off of her before she broke my fingers. But she did none of that. She melted right into me. I expected her to go running the moment I implied something sexual, but she stayed rooted in place with her pink lips quaking. They were begging to be kissed. I've never wanted to taste anyone so much.

When we were in high school, we got grounded for fighting. We've experienced a thousand fights between us, but we just happened to catch Dad on a bad morning.

It was on a weekend and we both had plans. We tried sneaking out, it backfired, and I remember hiding underneath the dining room table with her. That ridiculous blue eye shadow was dim compared to the actual blue of her eyes. I can still smell the perfume she wore and see that butterfly clip holding back a piece of her hair. I miss those butterfly clips. They were a staple our entire junior year.

I wanted to kiss her then despite trying my best to ignore the unwanted feelings. Dad and Marti were inches away from us. I chalked it up to our rebellious evening. Kissing my step-sister would have just been icing on the cake.

But then she ran upstairs, and I had no choice but to divert Marti's attention before running after her.

The moment had passed. A moment that I knew had been one-sided. But I'm not so sure it's one-sided any longer. If I took her in my arms and kissed her, I have a strong sense that she would kiss me back.

We walk into the party and the loud thumping of music does nothing to divert my forbidden thoughts. Casey and I barely spoke on the way over. Too much has happened between us today. Too many confessions. Too many touches. I can see the nervousness written all over her pretty face. I usually leave my leather jacket on. After all, it's a staple of who I am. It always has been. But I slide it down arms before throwing it onto the crowded coat rack by the door.

I'm hyper aware of Casey's gaze on me. She likes what she sees, almost as much I do when it comes to her. I've always known Casey was a knockout despite telling her otherwise. But I'm fairly certain that Casey has done her best over the years to ignore just how charming and attractive I am, too.

We look damn good together.

I walk up to her, my gaze never leaving her own. "Trust me," I mouth the words, knowing she wouldn't be able to hear me if I spoke softly anyway. There were too many people, and the music was too loud. Reluctantly, she lets go of her jacket so that I can drag it down her arms. My eyes drink her in one last time before I'll be forced to share her with everyone else.

Just as I'm taking my time gazing at her perfect tits, I hear a familiar voice come up from behind me. Casey physically jumps at the sound as it breaks through her trance. "Hey, man! 'Bout time you showed up."

I clear my throat, throwing Casey's coat over mine before turning around and hoping the agitation I feel isn't resting on my face.

"Hey, Thatcher," I say as Shawn pulls me into a quick bro hug. "It's barely nine. I'd hardly call that late."

"Castello's in the back where the real party is. Come on," he says, clapping me on the back. I grab Casey's hand, lacing our fingers together and reluctantly lead her through the throng of bodies hovering near the staircase. Tommy Castello is the campus drug dealer. He's been in school for seven years with no graduation in sight. I think he's just afraid to face the real world and acquire friends his own age, so he shows up to parties to get everyone high. He always gets invited back.

"Uh. I think I'm going to take it easy tonight. I'll just grab a beer."

"We just won the Championship, D. We've been on the straight and narrow for months. It's time to live a little before next season rolls around."

"I hardly call getting wasted every weekend 'the straight and narrow,' Shawn."

"Yeah, but when was the last time you had something a little stronger?" he winks.

"I'll think about it," I say, just to get him off my back. We reach the kitchen where he grabs me a beer, pops the top, and hands it to me between two fingers. I instantly take a sip, hoping that my nerves will finally calm themselves.

That's when he seems to notice Casey for the first time. He glances around me, taking her in from head to toe and the fact that are hands are laced together. She fidgets a little, uncomfortable at the sudden attention, grabbing my arm with her free hand. I know she's trying to hide herself behind me.

"Well, hello there," he says with a grin before nudging me with his elbow. "Where the fuck you been hiding this one? I thought sharing was caring."

"Watch it," I say harshly, giving him a seething glare. Shawn's smile falters before putting his hands up in surrender.

"Sorry, man. Off limits. Got it. Pity, though," he finishes with a wink in Casey's direction.

I take a deep breath, pinching the bridge of my nose. This was going to be a long night. "Thatcher. You remember, Casey."

"Casey?" he asks, confused at first. The hockey team goes through a lot of girls. It's easy to mix them up, forget who you've scored with, forget who you've met in the first place. "Casey…Casey…"

"You know. Casey."

He was going to make me say it. He was already several beers in, I was sure of it. If he had any chance of remembering her on his own, that moment was long past.

"My step-sister."

And that does it. A light bulb suddenly goes off in his head. "The hot step-sister with a stick up her ass! Of course, I remember you. You got pissed off when we crunched chips into the carpet."

Casey's nervous face instantly turns into a hard one, her eyes narrowing. "Yeah, that was me."

"Shit…I didn't recognize you. You look…" he gives a low whistle, chuckling. "Honestly, I'm surprised Derek is letting you out of the house looking like that. Ever since half the team said they wanted to take you out, we've been forbidden from mentioning you."

"Shut the fuck up," I hiss, hitting him in the chest. This was a bad idea. A very bad idea.

"Sorry, man." He says, holding his hands up in surrender once again, a cheesy grin on his face. And it was in that moment that his drunken smile begins to fall as he takes in the way Casey is holding onto me. He's finally starting to piece the puzzle together. This is the moment I've been dreading. I'll only have to do it a dozen more times at least before everyone became aware that my new "girlfriend" was none other than my own step-sister. "Is this – is she the new girl Sarah was telling me about?"

"Yeah. Casey and I are…seeing each other."

Shawn freezes before takes another sip of his beer, nodding his head like he's trying to understand this bazar turn of events.

"Just a sec," he says, walking over to the kitchen island and pouring himself a stronger drink before downing it. He then pours three more shots. Picking them up in unison, he brings them over to where we're standing. I let go of Casey's hand and we each take a cup from his grasp.

"I told you I'm taking it easy tonight."

"One for each of us, bro. You're both gonna need all the liquid courage you can get."

I give a heavy sigh, looking at the clear liquid in my hand. Shawn isn't wrong. I gaze down at Casey who is only two inches shorter than myself in the heels she's wearing. "You don't have to drink anything, Case."

"Carp diem, baby girl," Shawn says to Casey, lifting his own plastic cup in encouragement. Casey hesitates. I want to slap it out of her grasp. I promised her I'd be on my best behavior tonight, but one shot wouldn't hurt anything. It might be just what the doctor ordered to get us through the night.

We all click our cups together downing the liquid in one swallow. The familiar burn is more than welcome. I can't help but laugh when Casey coughs, making a disgusted face. "Bleh."

"Too strong, Princess?"

"You drink that every weekend? It's disgusting."

"You don't drink it for the taste, trust me."

I wave a hand in front of my face as we open the door to what appears to be an extra bedroom off to the right of the kitchen. A cloud of smoke reaches my senses and I instantly know it's marijuana. I've never personally tried the stuff, but I recognize it instantly. It was present at every high school get together I was invited to back in the day.

The room is dark, and it takes a moment for my eyes to adjust.

Derek is still holding my hand. I have to admit, I was a little nervous that he would ditch me the moment we arrived. I was used to him doing that sort of thing. He was always mortified to be seen in public with me when we were younger. But he's being attentive, just like he promised he would be.

My throat still burns from the vodka we had moments before. It tasted like gasoline, I'm sure of it.

But I have to admit, it did calm my nerves. I understand why people sometimes medicate with alcohol if such a small amount could do so much.

There are bodies sprawled out on the floor, some on the bed, and a few extra chairs have been placed around the room for seating. Obviously, this was the "cool" place to be. They even had their own music playing, much softer than what was pumping from speakers at the front of the house.

"Move it, Bryce," Derek orders, kicking at the shoes of a much smaller guy. This Bryce fellow rolls his eyes but doesn't argue before sliding to the floor. He doesn't miss a beat as he flicks his lighter. I hear a bubbling sound as he inhales from a long tube before blowing out an ungodly amount of smoke.

Derek sits in the now vacant chair, pulling me down onto his lap. Thank God he catches me with ease, because that would have been a disaster if I ended up butt first onto Bryce's head.

I'm sitting in Derek's lap. I'm trying to act cool about it and not adjust myself too much. The only times I've ever sat in Derek's lap prior to this moment was on complete accident when we fought over the remote.

But this moment is entirely different. Entirely too intimate. Was I ready for something like this?

Get a grip Casey. It's not like he's ripping your dress off in front of a crowd of people.

"Just relax," Derek says so that only I can hear him.

"I am relaxed," I lie.

"I can tell." The sarcasm is heavy in his voice. I hold my breath when he tugs the hem of my dress down a bit, his fingers lightly grazing my bare thigh. "I was hoping that shot would have loosened you up a bit."

"I'm sure you can't tell, but it did."

"You're right. I can't tell."

"Yo, D," someone says from our right. It's an attractive dark-skinned man sitting on the floor, one arm wrapped around his knees as he holds up a joint to Derek.

"Not tonight, Devin. I promised to be good."

"Ohhhhhh," Devin replies, taking another hit himself. "I've heard about your new lady friend. I'd be good for a girl like that, too."

"Let me guess? Sarah told you all about it."

"She's so fucking pissed man," he says with a laugh while holding his breath. "I don't think any guy has turned her down. Especially for another chick."

"That's only because she's a sure thing. I've never been big on sloppy seconds anyway."

"Right, right," Devin concurs, clearly amused by the whole thing. "We usually get your leftovers. Not the other way around."

I'm not finding this conversation amusing in the least, especially since Derek seems to be completely oblivious to the problematic behavior of the whole situation. Using girls in that manner was wrong. Anyone with a single brain cell could come to that conclusion.

But I can't stop but wonder if he would he use me like that if we ever went far enough? Surly not. After all, it's not like he could just discard me like other girls. Our parents are married. We share a little brother. Holidays would be incredibly awkward.

"You okay?"

"Hmm?"

I snap my head to attention. I had drifted off into my own world, and surprisingly, Derek had noticed.

"Yeah, I'm fine."

"Move it, move it. Coming through," a loud voice breaks through the calming stoned silence. "The party started hours ago, man. Where you been?"

"It's not my fault you guys start drinking before the sun goes down."

"Whiskey on the rocks for my guy," Cole says, grabbing the beer out of Derek's hand and placing an overflowing cup back into Derek's palm. It spills over a bit.

"Shit," Derek says, instinctively licking the amber colored liquid off his hand.

"And for the lady?" Cole asks, giving me a wink in the process. Why is everyone winking at me? "I don't think we've been properly introduced. I would have remembered a girl like you. You must be new around here."

"Ummm…I…"

"It's Casey, Summitt," Derek says, his tone clearly irritated as he sips from his overfilled glass.

"Casey?"

"My step-sister."

"No," he pauses, clearly not believing it. "Last time I saw you, your nose was buried in a book, and you looked like you wanted to murder us. You were still cute though."

"Wait, wait, wait. No shit," Devin chimes in having listened to our conversation. "Step-sister? You blew off Sarah for your own step-sis? Fuck. I didn't think shit like that happened in real life. She's going to be so piiiiiiissssed," he finishes, finding the situation hilarious apparently.

"If my step-sister looked like that, I'd fuck her, too." Bryce chimes in for the first time while still focusing on his bong. "You know…if she wasn't forty and married with three kids."

I can feel Derek's grip tightening around waist. He's trying to compose himself, but honestly, what did he expect? We knew it was going to go one of two ways. Disgust or fetishy. So far, we've got a mixture, I'd say.

"Soooooo, how old were you when you all met?" Devin asks, genuine curiosity written all over his chiseled features. I know he's asking if we grew up together just to see how gross our relationship really is. Derek's jaw is working in overtime, and I know that he has zero intention of answering.

"Fifteen," I offer, fiddling with the watch around Derek's wrist that is currently resting on my bare thigh.

"Yeah, that is kind of hot. So, you guys been fooling around for long?"

"I swear to God if you don't…"

"Ooooookkayyyy," Cole cuts Derek off before an inevitable fight breaks out. I'm grateful for the interruption. "About that drink, Casey?"

"Ummmm..I…"

"She doesn't drink," Derek offers taking a long swallow of his own. I know we made a packed that he wouldn't drink heavy tonight, but something tells me he needs it right about now.

"How about a screwdriver. Hmm? Easy to make and it tastes good."

I give an appreciative grin. "Thanks."

"Coming right up."