A/N: So. I think this was supposed to be a Quinnshot fanfic but I got distracted and started reading some Dasey fanfic and this lovely thing that I do not know how to describe popped out. So uh enjoy. PS: Don't worry I'll try and get back to work on the Quinnshot fanfic immediately. I also overused the shit out of parentheses so I'd like to apologize. Oops.

Summary:"Huh." I was actually fantasizing about you panting my name but since that's not exactly Casey friendly information, I think I'll just stick with the 'huh.'- In which Derek's in like (love) and Casey's oblivious. You know the usual.

Approx Word Count: 3000

Shit. Shit shit shit. What the fuck was he going to do? He fucked up. He fucked up royally. Like, if somebody tried to calculate how much he fucking fucked up on a scale of one to ten they would get a fucking twenty seven.

Fuck.

Derek Venturi had a bit of a predicament.

Well okay it was actually kind of a massive predicament. One that involved a certain someone who's name started with a "C" and ended in "-asey."

At some point between when she moved in and now, he may or may not have started feeling (ugh) things that aren't exactly brotherly- step- step brotherly -towards the aforementioned crazy as fuck female.

He wasn't sure how it happened. This was Casey keener, klutzilla, nerd extraordinaire and she was unattainable. He supposes that was part of her allure. The whole forbidden fruit thing she had going on. Especially when he was always accidentally (purposefully but not like in a creepy way) managing to catch her on her way out of the bathroom.

Or maybe it was the fact that she was the only one who would get riled up by his (reluctantly admitted) childish actions and (at least attempt to) knock him down a peg.

Or maybe it was the way her face would flush whenever they fought. The red shade spreading across her face, down her neck to her chest, and all the way to- an off limits and barren area where Derek is (unfortunately) never allowed to go.

Whatever it was that caused this sick (understandable; he was a boy and well she was a girl (which he reluctantly admitted as the previously mentioned off limits and barren area proved it to be true) and he was hormonal okay, he doesn't have an excuse for his current urgh) attraction all he knew was that he was fucked. Fucking in like (love) with Casey McDonald. Go figure.

The day had been pretty normal. Classes, hockey, home. Derek had hit all three and was feeling pretty good about himself.

Flopping down on the old dusty couch he turned on the TV and changed it to TSN. The Oilers had a game and he definitely wasn't going to miss it. They better win it's been fifteen fucking- The sharp shrill of the doorbell drags him out of his thoughts and over to the door.

He pulls it open and leans against the doorframe prepared to politely (rudely) dismiss whoever thought it would be okay to visit him. And on Oilers day no less.

"DON'T SHUT THE DOOR!" a feminine voice screeches. He starts. Dammit. It's Casey. He's probably (definitely) not even going to get to watch the game today. He sighs and keeps his hand on the doorframe.

"What do you want?"

She ignored his rude greeting, "I was thinking I could make you dinner." Her arm raises and his attention is immediately directed to the bag of groceries he failed to notice when he first opened the door. He forces his eyes to flit back to her face away from the cream colored skin of her arms.

He blinks and focuses again. Dammit Derek pull yourself together. A smirk takes over his features. He raises his eyebrows and shakes his head so she won't realize he was staring at her (what the fuck dude) arms.

"Casey." He shakes his head, "Casey Casey Casey. Don't you know it's Oilers day." His smile becomes a little more genuine at the roll of her eyes, "If you missed me you could have just called. Or not called. That would have been great too."

She scoffs "Please Derek," she falls into him dramatically and Derek has no option but to hold her up. (Well he could have dropped her but he supposes he's matured a little. Just a little.) "You know you dream of hearing my voice and every day you don't is a little worse."

He responds in regular Derek fashion "Sounds like the stuff of nightmares." Although her words did hold a ring of truth; after they moved for college they kept in touch more in need of some kind of familial (step-familial? anything to create more distance between family and the two of them because 99% of the thoughts Derek had about Casey weren't familial at all unless you were talking in terms of making one) connection to keep themselves sane. Every day he didn't talk to her he would reluctantly admit did suck a little more.

Casey rolls her eyes ignoring him and leans out of his arms and he finds himself missing her warmth. Derek what the fuck you've become a fucking love- wait not love- like- a fucking likesick monster. Get it together.

She flashes a fake smile at him and ducks under the arm that was supposed to be blocking her entrance.

"You've redecorated. Huh. Looked better the other way." He rolls his eyes and watches her as she makes her way through the living room casually cleaning as she goes in a way only Casey McDonald can.

She reaches a particularly old looking slice of pizza and shrinks back in disgust. "How can you live like this?"

Well, he's also in love- like he's also in like with his step (never forget the step)-sister so he supposes leaving a slice of pizza out for a while isn't all that bad (or taboo) in comparison.

He shrugs and flops back onto the couch attempting to watch the game he probably (definitely) won't get to finish and there's a hip check and it's just getting good when "De-rek!" is heard a shrilly screech from down the hall. He considers stuffing his head in a pillow and staying there until his sad shell of a life (seriously he's in love with Casey McDonald, just kill him already before the stress that just emulates from her kills him itself) can end but then he remembers the game and realizes with resignation that he doesn't want to die before the games over. He at least wants to be alive until tomorrow to see the highlights of the game he probably (definitely) won't be able to watch. After which he will promptly stuff his head back into said pillow and finish what he started.

He sighed and trudged his way over to Casey another "De-rek!" about to rip from her lungs when he entered the room.

"Great! You're here now you can do the dishes so I can-"

"Woah woah wait a minute Case," (he was older now and immature nicknames like Klutzilla and Space Case and Princess were reserved for the most special occasions. "Let me get this straight. You came into my house-"

Casey interjected "It's a flat you dumbass."

He placed a hand over his heart. "Casey was that- was that" he gasped for effect "an expletive I just heard come out of your mouth."

She rolled her eyes again. She did that a lot around him. "Oh fuck off Derek."

The word rolled off her tongue. It seemed like it belonged there. "You have an even worse potty mouth than I do. In fact it's probably your fault I curse as much as I do anyway." She grimaced, "In fact I was talking to Marti the other day and I said 'shit' like it was nothing and she almost had a heart attack."

Derek wasn't really paying attention at this point. He was still stuck on the- well "fuck" and he was currently imagining her saying it in a far more horizontal position and in a much more breathy way.

Suddenly fingers snapped in his face. "Derek?" Why is your face so red?" She placed her hands on her hips "Did you hear anything I just said."

"Huh." I was actually fantasizing about you panting my name but since that's not exactly Casey friendly information, I think I'll just stick with the 'huh.' He said it again in what he hoped (it wasn't) a more convincing manner. "Huh? Case I'm still having trouble accepting the fact you've wormed your way into my home. You expect me to be able to process the presence of vermin in my house and what said vermin is saying at the same time." He shakes his head "You're letting your expectations get to high"

He sighed relieved because coming up with insults for his (hot) step (emphasis on the step)-sister was a lot easier than continuing to come to terms with his growing affections for said (hot) step (emphasis on the step)-sister.

He couldn't look at her but he was pretty sure she'd rolled her eyes for the umpteenth time since she'd walked through his door. She ignored his jab (the only downside of Case growing up was her growing resistance to his taunts (although Derek would just tell himself it was because she was incapable of response due to her spastic tendencies)), and responded.

"What I was saying before you so kindly called me vermin." She glared at him and he thought he just may get his very own Casey McDonald insult. He's coming up with his speech to thank the academy (gotta thank Nora for producing such combative offspring and George for marrying Nora and Lizzie for not desensitizing her to childish taunts and Emily for always-) for such an amazing honor when Casey begins her verbal tirade.

"Which by the way is completely hypocritical since you live in a literal pig sty. Seriously I'm surprised I haven't seen any" she makes finger quotes and rolls her eyes "'vermin' in here." She pauses sending Derek a fake smile "Other than me of course." Her voice was dripping with sarcasm and Derek would think her flushed thinking/frustrated face was really sexy if- nope it was just really sexy. He wondered how far the blush reached and- nonono nope now is not the time do you really want Derek Jr. making a surprise visit right now. Keep it in your pants Venturi.

Derek just smiles the one he reserves solely for annoying Casey it's a little crooked and tad wide but he thinks it fits. "What did you want me for again? You know while I don't care, I also don't listen but you know how it is. I'm trying to be kinder."

Casey looks shocked but before she can get in a scathing remark he jumps in. "It's very important to treat animals with respect you know."

She shakes her head as if she shouldn't have expected anything more. "It is. I suppose that's why it's such a pig sty in here. You simply must be trying to appease the piggies that have got to be in here somewhere for it to look so terrible." She shivered clearly revolted by his current state of affairs.

"Aww Case don't you know the rules. You can't repeat an insult." He sighs "Guess you lost."

"Did not."

"Case I understand you enjoy engaging in juvenile pursuits but-"

"Wow Derek that's a three syllable word you can finally go to third grade."

"Keener."

"Jerk."

"Klutzilla."

"I haven't even tripped although I'm surprised I've managed to stay upright in this." She looked around and upturned her nose "I don't think I can find a proper word for this. Pigsty doesn't even do it justice."

He pumps his chest and stands proudly. "Thank you. I'm just glad it made you speechless. If only for a moment. Have I told you how much I hate the sound of your voice?" Casey is about to jump in when he cuts her off "Also, Case, you can't just keep breaking the rules like this. Don't you have anything to attack than my admittedly clear cleanliness issues?"

"Yes. Let's see: your inferior intelligence, your subpar hockey skills," He gasped but she didn't let it deter her "And your stupid messy hair." She ruffled it even more and Derek squirmed away from her hand. "And- and sorry I can't focus anymore I think I might be contracting a gaseous-ly transmitted disease. This place fucking reeks. I know cleanliness is supposedly" she made finger quotes and rolled her eyes "'off limits' but how did you manage to get it to smell that bad in here."

There was that word again and he's in the same boat he was in before saying "huh" and insulting her to evade the nightmare (dream) that damn word conjured in his thoughts. This damn woman had no idea what she was doing to him. "Shouldn't you be leaving? You've already been here too long and 1. I have an Oilers game to watch and 2. you still haven't made me dinner."

"Derek that's what I called you in here for in the first place but you went and started with your childish taunts-" she raised her hand as Derek's mouth opened "Don't even." His mouth shut. "Now do the fucking dishes so we can have stuff to eat with."

"Ok Case now it's just excessive."

"Just shut up and do the dishes."

"Aye aye Captain." He saluted her. Now usually when this happened he was asleep and they were, again, in a much more horizontal position (he liked role play sue him) but he shook his head of the unpleasant (stop lying to yourself Derek) thoughts and got to work washing the dishes. He did want dinner after all. And if his position at the sink gave him the perfect view of Casey's ass while she was cutting vegetables, well who was he to deny the captain?

As Casey cooked and Derek washed the dishes he'd make the occasional snide comment which generally leads to a "De-rek" being uttered which is almost as bad if not worse than the "fuck." But, Derek had always been a bit of a masochist so he continued with his annoyances despite her half-hearted protests and the issue he'd have to deal with later involving a little (a lot) of lotion and quite a bit of tissue.

At some point Derek finishes the dishes and Casey is done making the food and if he maybe cleaned up a little after he finished his duty (heh) it wasn't for Casey- no it was for the- the uh vermin whom he invited (or forced their way) into his home. Which more or less was the same thing but he figures that's irrelevant and tells his brain to shut the fuck up.

So they sit.

Together on that weird bar table he has which had previously been full of papers before he cleaned up for Ca- the vermin they eat. His damn brain was betraying him again. He goes through this a lot. Having to convince and remind his mind that even if she was interested (which how could someone not be interested in the Derek Venturi; although if someone were not to be interested he thinks it would be just his luck for it to be the girl he liked. Given that said girl also happened to be his step (emphasis on the step)-sister) she was still in fact off limits even with that four letter word that preceded the (supposedly) more important word, "sister" in his face.

So they sat. And they continued to eat and for some reason it felt different.

Casey's looking at him with eyes that look content and excited, a look he never really sees directed at him except for when he has those rare "good Derek" moments. God he hates that guy. Always doing the right thing and making Casey make that face and it- it just (it really doesn't) revolts him.

The whole ordeal feels oddly domestic; them bantering like an old married couple and the cooking and the cleaning and he thinks maybe he could do this. He thinks maybe he could somehow live a life like this with a girl (Casey) and not hate it. He had previously pledged to a life of bachelordom but there Casey goes with the whole ruining his plans thing she has going on thwarting him again. Going to work coming home. Coming home to Casey-

"I'm engaged!"

(And there she goes thwarting another one of his (highly unlikely) plans.)

Derek's whole world comes crashing down. Dreams of a domestic life with Casey warped. His face replaced with some no name guy who isn't her step (emphasis on the step; although it doesn't particularly matter much anymore) - brother. Someone who isn't complicated and fits that perfect little cookie cutter box Casey has always wanted. Someone who works for her. Someone safe. Exactly what she needs. Someone to tone down her crazy. Casey was never the type to heed his advice and "live a little dangerously."

If Derek was a good step (emphasis on the step although it may not matter as much now) - brother he would be happy for Casey and not feeling broken on the inside. A current of emotion ripping through his heart. And since Derek doesn't do this feelings shit, he nods and smiles.

It all makes sense. Why she showed up unannounced. Why she didn't bite back at every remark she made. Why she decided to cook him dinner. It was as if she had known. Like she wanted to let him down easy. If only she knew. Actually that might not be a good idea there would probably be somewhere in the neighborhood of eight neurotic breakdowns.

And then Derek's brain stops. Derek's brain stops and realizes that he is completely, utterly, and truly fucked.

In like (love) with a girl (his step (emphasis on the step although it definitely (probably) doesn't matter anymore)-sister) that he can't have. Even more off limits than she was before. And this time the whole forbidden fruit thing wasn't sexy. It was just fucked up.

All Derek can think is, well all he can think is:

Fuck.

A/N: Hey yall, love ya and reviews and favorites are always appreciated. Hope ya liked it! Sorry if you thought this was the new chapter guys. There were some typos that were really bothering me. I wonder if I should get a beta. Hmm. Anyway. I'm working on the next chapter now! So we''ll see how things work out for poor Derek.