Derek overstayed his welcome at Casey's apartment, so much so that he started getting mail delivered there. He was getting too comfortable with sleeping on her couch, eating her food, and having her clean his messes.

Despite Derek being lazy, he was on his best behavior when it involved pranking Casey or insulting her for the fun of it. For the most part of his stay, he was quite mellow, but the Venturi men couldn't be held on a leash for too long.

When Casey decided to go out on a date with a nerdy guy from their French class, Derek found himself extremely irritated by this. Lately, his game with the ladies was off, and he was trying to be considerate not to bring any girls back to Casey's apartment. He knew she wouldn't want to see him making out with randoms on her precious clean couch. But now that she was off on a stupid date, leaving the apartment at his disposal, he decided to have a little fun of his own and texted everyone, especially the girls, he knew to come out for a party.

The party was like every other he had thrown in the past, only this time, there were college students instead of high school students, and his parents weren't going to come in and suck the fun out of it.

When Casey arrived back from her date, earlier than expected, she nearly had a heart attack when she heard what was going on inside. The music was so loud she almost called in a noise complaint on herself!

"I'm so sorry about this." Unlike Casey, her date didn't make much of a fuss when he heard the music coming from her apartment.

Casey fumbled for her keys, embarrassed at what was unfolding before her. This was supposed to be a really nice date with a perfect end-of-the-night kiss, and Derek ruined everything!

She stood in the doorway for what felt like several minutes until she found the nerve to step in. Every step she took was met with loud crunching noises from the crumbs that stuck to her heels. The place was a disgusting mess!

She pulled a couple of people off of her kitchen island and broke up a makeout session on her couch before searching the crowd for Derek. Of course, he was flirting with the prettiest girl in the room, unaware of the devil in a dress walking closer to him, prepared to ruin his fun.

Casey tugged on Derek's ear until he was forced into a corner far away from his flirtatious guest.

"Woah, woah, watch the merchandise! Couldn't you see I was having a conversation?"

The nerve! The audacity! The gull!

"I can't believe you, Derek! I leave you alone for two hours and come back to a party in my apartment?!" She was yelling, partly because she wanted to and partly because the music was so darn loud.

"Don't you mean our apartment?"

"Derek, you are barely a guest! I pay for this place, and my name is on the lease, not yours! I want all of these people out of here!"

Seeing Casey so riled up was the cherry on top to a great night for Derek. He didn't dare make a move to ruin the first college party he was able to throw.

Casey knew Derek wouldn't end the party on his own, so, in a blind rage, she threatened to cut the wires to the stereo system. At first, Derek didn't believe her until she returned to the living room holding a pair of Betty Crocker kitchen scissors. It was then that he realized he shouldn't have underestimated her.

"Casey, Case, just put the scissors down before someone gets hurt." Derek approached cautiously, his hands reaching for the pair of scissors. The person Derek was most concerned about getting hurt was Casey herself. She wasn't the most graceful person he's ever met.

"You don't know anyone here, I don't know anyone here, this place is a mess, and I've got two tests to study for!" The freak out was real. Luckily, Derek took the scissors, or she might have given herself a spontaneous haircut!

"Okay, calm down. I'll just -" Derek looked around the room, scratching his head. The party just started, so he wasn't sure how to kick everyone out without cutting off the stereo and becoming the biggest loser at college.

"Casey, I think I'm gonna go." Well, there goes Casey's date! Josh was such a sweet guy, and yet, here she was, fighting with Derek and ruining their night.

Derek didn't like Josh anyway. The last thing he needed was another nerd around spoiling his fun.

"What? But Josh!"

"Sorry, Casey; you know I have a curfew. Bye, guys." Josh waved goodbye.

"Bye Josh," Derek smirked, wiggling his fingers at Josh.

Good riddance. Believe it or not, that guy was more of a keener than Casey! Who actually sets a curfew for themselves at college? He was a bad influence in Derek's mind.

"Derek! You are the absolute worst human being on the planet!"

"That an honor, not an insult."

Casey hit him on the shoulder, causing Derek to wince in pain.

"I've been so nice to you by letting you stay here, and you pull something like this?"

"Like what? It's a party. You should thank me for giving you a nudge into popularity."

"Derek, no one even knows who I am or that this is my apartment, so that's irrelevant. I could disappear and no one would notice."

"Okay, then go to your room and go to bed, grandma. The party will be over in no time." Derek started to turn Casey toward her room, but she stopped dead in her tracks. She wouldn't give him the satisfaction of leaving.

If he wanted to play dirty, she would play dirty back.

"You know what, Derek? I think I'll stay after all. If you want a party, I'll give you a party!"

With anger laced in her veins and Derek clogging her better judgment, Casey stole a beer from the first guest she made eye contact with, drinking it straight from the unsanitary bottle. She hated beer, and moreso, hated alcohol in general, but she was in rare form tonight.

"Casey, what the hell are you doing?"

Protective Derek mode had crawled out from beneath the surface of a rather smug exterior.

"I'm having fun, duh!"

The plan, at first, was to get so drunk she would make a terrible fool out of herself so that no one would want to come back to her apartment, but instead, all it did was slow down her reflexes and cause her to mellow out.

Derek spent the entire night watching over her, trying to stop her from drinking and flirting with a bunch of hormonal college guys. He hadn't enjoyed a single sip of alcohol since Casey walked through that door, and his smooth moves with the ladies were all but lost.

"You should come back to my place."

Derek snapped his head so fast to the side that he nearly hurt himself. Whichever guy was taking advantage of Casey was about to have his will and testament written for him.

"Where are we going?" Derek managed to slither his way into the conversation with ease, his aggressive demeanor changing only slightly when Casey backed away from the flirtatious college guy.

"I was talking to her." The drunken sleazeball pointed his drink at Casey, unaware of the obvious hint Derek was giving him to step aside.

"I think she's comfortable where she's at, but thanks for the offer," Derek declared.

Casey, drunk off her rocker, smiled sweetly at Derek and grabbed onto his shoulder.

"You're right; I am totally comfortable and relaxed! I was just about to play spin the bottle with my new friends. You should join, too," she said, looking over at the asshole trying to use her.

Derek tugged her back to his side, not letting the other guy get any ideas.

"No, Casey, you should be going to bed."

Oh God, he sounded like Nora.

"Aw, is someone upset he's not in charge?" Casey pinched Derek's cheek before taking a seat next to the group of her so-called new friends.

Casey would be having a fit about the mess on the floor if she wasn't so wasted. Derek missed that side of her. Clean Casey was miles better than Drunk Casey.

"Come on, you should join, too!" Some of the girls on the floor shouted for Derek to join in.

Derek wasn't in the mood for games, but he also didn't want Casey to be taken advantage of by the guys in the group. The best way to keep her protected was to join in on this little game until Casey had enough of this charade.

"Alright, one round, and that's it, Casey."

"Okay, grandpa." Oh, he did not like this role reversal one bit.

Once Derek sat down beside Casey, one of the girls reached for the empty bottle of Coke and spun. Casey was getting dizzier by the second as she watched it turn around and around on the floor. She got even dizzier when she noticed that the darn bottle slowly landed on her.

Derek held in a sharp breath.

Who was she going to kiss? Every last guy in this group was a raging frat boy, apart from Derek.

In her drunken state, Derek knew it was bound to be a sloppy, wet kiss, and there was no way he was going to watch her stick her tongue down some frat boy's throat.

Derek looked over at Casey's glossy, pink lips and became visibly shaken. There was a burning sensation in the back of his throat so severe he couldn't swallow, and he felt a sudden urge to lift her into his arms and take her away from this horrid party. Of course, he didn't. Instead, he sat there helpless and hoping the bottle would somehow shatter to pieces.

The bottle felt like it spun for an eternity on the second go. When it finally stopped, Derek noticed it landed on him.

He let out a sigh of relief.

Phew, she didn't have to kiss anyone because it landed on him.

And...

That's when he realized...

The bottle landed on him!

Derek's mouth suddenly went dry, and he felt the room around him start to spin as if he were the one that was drunk. He glanced at her lips once again but quickly looked away this time. Panic started to settle into his veins.

"Are you going to stare at her all night? Don't be a prude! Kiss her!" They shouted for Derek to make the first move, but he stayed anchored to the floor.

Derek Venturi was no prude by any means, but when it involved his stepsister, they might as well have fitted him for a clergy robe.

It wasn't the girls' fault. They didn't know Casey and Derek were related by marriage.

"Kiss her, or you both have to take a shot!"

Casey could barely keep her eyes open, and yet she reached for the shot. She was nearly passed out, and she'd still prefer to take a shot over kissing her stepbrother.

Derek quickly pushed her hand away before she could bring the glass to her mouth.

"You are not drinking anymore, Casey." Derek was dead serious. He didn't have an exact count of how much she drank, but he knew it was more than his own normal fill.

"But..." She eyed the drink once more.

"I said no."

"But Derek..."

"Christ, I'm gonna regret this."

Derek slowly reached over, placed his hand on the side of Casey's jaw, and gave her a quick peck on the cheek. Her skin, momentarily recognizable on his lips, made his heart skip a beat. The thought of being so close to her lips produced a buzz no alcohol could inflict.

Casey immediately tensed, her normally fair skin turning a deep shade of red. Of all the times she's embarrassed herself, Derek doesn't recall ever seeing this particular color on the swatch.

To those select few watching in anticipation, the moment came off as lackluster. The cheek kiss received united boos from the crowd, and the group screamed for Derek to kiss her on the lips, almost as loudly as his own brain was screaming for him to do the same.

Casey, ignoring all of the voices, stumbled to her feet, and Derek followed her to make sure she was okay.

As Casey reached for the metal doorknob to her bedroom door, she turned toward Derek with malice. Her eyes sent daggers straight to his vulnerable chest.

Honestly, Derek couldn't have been happier to see her this angry. It meant she was disregarding that stupid kiss and going back to their scheduled argumentative relationship.

Ugh. Derek cringed for even thinking about using the word relationship to describe them.

"Tomorrow, I want you out of here! This party was lame, and I'm drunk, and it's all your fault!" Casey pouted as if she had been hanging around Marti too much.

"I didn't tell you to get drunk; in fact, I told you to do the opposite. And need I remind you, I risked my reputation by kissing you instead of letting you take another shot," he said, clasping his hands together.

Shit. Why did he bring up the kiss? What was wrong with him?

"I would rather have taken the shot," she snapped back, wiping at her cheek as if doing so would wipe away all of his germs.

He knew she wanted to take the shot over the alternative, but hearing her say it out loud cut him deeply. His ego was bruised. That's all.

"Said no girl ever," Derek argued. It was as if he had to prove he wasn't a bad kisser.

"Said Kendra, said Sally, said..." Casey started to make a list with her fingers when Derek stopped her.

"You're making that up."

"Am not. Maybe you don't kiss as well as you think you do."

She liked this. Getting a rise out of him. It was their own special little game.

"Do I need to prove it?" He immediately regretted his words. It didn't help that he was unintentionally close to Casey during their argument, so close he could reach out and - no! Bad Derek! Very, very bad Derek!

Casey wasn't sure Derek really understood what he was saying, and heck, she was so drunk that she barely understood. It was best to leave an already horrible argument alone, and she really needed to get some rest.

She slid open the door to her bedroom and slammed the door in her stepbrother's face before things really got out of hand.

As the party dwindled down, Derek Venturi did something he never thought was possible without an authority figure around: he cleaned.

This was their routine. Derek would bring Casey to the brink of committing a felony against him, and then he would create some grand gesture so she would forgive him.

As Casey heard the party die down, she exited her room. She wouldn't dare look at the ornate mirror hanging on the wall, as she probably looked like hell, blue eyeshadow smudged and hair all a mess.

"Be careful without your shoes on; there's broken glass over there. And don't worry, I'll have this place cleaned up by morning. I'll be out of your hair by then." Derek chucked another piece off glass into the trash bag, wiping the sweat off of his forehead. Casey watched him work his way around the room for a moment before finally speaking.

"I need your help unzipping my dress so I can sleep," she muttered bluntly.

Derek lost all sense of feeling as her words hit him like a ton of bricks. Luckily, he wasn't holding any broken glass, or else it would've cut right through his skin.

Casey was embarrassed to ask for help, especially after their argument, but she couldn't reach the zipper. Being drunk didn't help her coordination skills, either.

"Uh, can't you sleep in what you're wearing?" He knew she must be uncomfortable in that tight, skimpy number she was wearing, but he didn't want to be the one to unzip it.

"It reeks of alcohol, Derek. It's the least you could do after tonight," Casey turned around as if to give him better access to her dress. She half-expected he wouldn't help her with this problem, but waited patiently anyway, as she didn't have a better option. Soon enough, she could hear cautious footsteps approaching, and then she felt Derek's breath against the back of her neck. She tried to ignore the way her body responded to his presence, focusing on moving her ponytail out of the way so he could access the zipper.

"Hold on; it's stuck," Derek murmured. He was getting frustrated and had half a mind to rip the entire dress off. Forget the zipper.

"Oh, I thought you'd be used to this."

Oh, she was really drunk. Otherwise, normal Casey would have never ever said this out loud, even if it was meant to be a silly joke.

"Why would I mess with a zipper when I could just go under?"

He didn't mean to say that. Wait, he definitely meant to say that, but he shouldn't have said that. Not to a drunk girl, and most certainly, not to Casey McDonald. Unfortunately, saying inappropriate things was becoming quite the nasty habit tonight.

Tug.. tug.. tug. Derek placed his hand on her back to balance himself as he repeatedly pulled on the zipper. If it hadn't been for Casey's hand against the wall, she would have fallen onto the hardwood floor.

The zipper finally let loose, and he yanked the darn piece down before walking away. The last thing he wanted to get was a glimpse of her bra and panties, so he made his exit quick.

Casey's entire body was on fire, and it wasn't from all of the drinks.

Holding her dress to her chest, Casey turned around.

"Derek?" She called out.

"Yeah?" He kept his eyes far away from his stepsister when she called out for him.

"I'm not kicking you out. I'm still mad at you, but I'd hate for you to sleep under a bridge before you even have a chance to fail this semester."

Derek smiled to himself. He got the girl out of her dress, and now, she wants him to stay? Story of his life.

"I knew you were bluffing." He thought she was bluffing, but one can never be too sure. Cleaning the apartment had been his way of smoothing things over so he wasn't kicked to the curb.

"Yeah, yeah. Goodnight, Der."

"Goodnight, Case."