Derek's only been gone for twenty minutes - twenty tiny, inconsequential minutes - but he still returns to his apartment just in time to overhear Kira say, "I don't know. I mean, it can't be that bad if you're pooped on by someone you love, right?"
He slips through his door as the laughter is dying down. Kira flushes bright red and it makes him weirdly proud, in the way that he'll always be a big brother determined to embarrass the shit out of the younger women in his life.
"If you promise to never tell me what you all were discussing," Derek says, setting four grocery bags bursting with snacks on the coffee table everyone is more or less situated around, "you can help yourselves."
A few people thank him as they all descend on the bags like they haven't eaten in days, and Derek knows they're just being normal college kids when presented with free food but it still makes something uncomfortable twist in his gut, makes him want to provide and other shit he's too embarrassed to even think about most of the time.
The conversation mostly falls to who wants what brand of chip until Lydia says quietly, assuredly, "I bet Derek has some really freaky kinks."
Everyone goes silent at that, turning to gape at Derek. He wants to glare at Lydia, wants to not flush to the tips of his ears like he's positive he's doing, but mostly he wants Stiles to stop giving him that searching, assessing, unsettling look he's giving Derek right now. He's distantly aware of the awkward laughter and groans from the others, but his eyes stay locked on Stiles'.
Finally, Stiles turns to Scott to say something probably related to the conversation going on around them. Derek takes a deep, steadying breath.
It takes him a solid three minutes to be able to focus on anything other than replaying that look Stiles had given him.
"I can't stop thinking about you," Stiles says, breezing into Derek's apartment a few days later, completely uninvited, using a key Derek definitely didn't give him. (Derek won't ask for it back though. Keys are like Hydra with Stiles: ask for one back and two more grow in its place. At this point Derek's just tired.)
"Shouldn't you be out doing anything else right now?" It's New Year's Eve. Surely Stiles can come up with something better than annoying the hell out of Derek.
"Nope," Stiles says, flopping down next to Derek on the couch. "I stopped by Scott's party for about an hour and saw this couple just, you know, going at it in the middle of his living room. We're talking, a generous use of the word 'dancing'. And all I could think was, I wonder if Derek's into exhibitionism."
Derek stares at him for a long moment before finally letting out a flat, "What."
"Ever since Lydia's comment, it was like Lust-o-Palooza, population Stiles."
Rubbing his temple, Derek sighs. "Please stop."
"Believe me buddy," Stiles huffs out a laugh, "I wish I could. I haven't masturbated this much since I was fourteen."
"Late bloomer," Derek mutters before he can stop himself. He peeks over at Stiles, hoping the comment went past him, but the damage is done.
Stiles looks way too gleeful when he asks, "Do all born werewolves mature early, or is that a Derek thing? Is that a Hale thing? Do you think Cora would be mad if I called her to ask? She'd probably be mad. Right? How is she, by the way?"
"She's fine. She's also your age," Derek says meaningfully.
"Nope. Not a valid argument out of this. I'm twenty two; way past the age of consent. I'm actually past all age laws." Stiles pauses. "Except I can't teach anyone else how to drive. But I'm solid on everything else."
Derek studies him for a few moments, watches Stiles watch him right back. The fact that it doesn't make Derek uncomfortable, actually makes him feel fond and happy and other gross shit, convinces him to say, "Okay."
"Okay." Stiles nods his head, then pauses. "Wait, what?"
"Just come here."
Derek isn't naive enough to expect Stiles to close the distance between quietly, but he also never anticipated that the words, "Alright, we're going to have ourselves a Sex Marathon. A Sex-a-Thon if you will," would ever leave anyone's mouth ever, let alone someone Derek's just willingly, soberly agreed to have sex with.
"I will not," Derek grumbles, but he's already shifting lower on the couch to make it easier for Stiles to climb into his lap. It's just. Sex-a-Thon.
"Sure you will." Stiles says this easily, as if there's not a doubt Derek will give in. "New Year's Sex-a-Thon. Has quite a ring to it don't you think?"
Derek marvels at his self-confidence. It's certainly not as if Derek has given him any reason to think he even has a shot, and Stiles gets rejected much more often than he finds someone willing to even make out with him.
Here they are, Stiles swinging a leg over Derek's thighs to straddle him, without a trace of fear or uncertainty. Derek's hands curl at his sides, uncertain of what to do. Which is frankly absurd because it's not like he's a virgin. Why is he over thinking this?
His hands are half-way to Stiles' hips when Stiles leans forward to say, low in his ear, "Oh look, the ball's dropped."
There's actually three seconds left and Stiles' comment reminds Derek of pre-pubescent boys, making it disturbingly unsexy, but then Stiles starts nipping down his neck and it's a nice enough distraction that he decides to let it go.
"Biting, yes or no?"
It takes Derek a moment to realize Stiles is asking a question.
"Biting." Stiles pulls back just enough to look up at Derek through his eyelashes. "Do you like it or not? And would you rather do it to me?"
Derek sighs and sets a hand on Stiles' lower back so he can flip them over, laying Stiles out on the couch underneath him. "Are we going to have sex, or am I filling out a questionnaire?" At Stiles' gleeful look, Derek adds, "If you say 'sex-tionare', I'm kicking you out."
"You're no fun," Stiles mutters, but he surges up for a kiss so he can't be too upset.
Stiles kisses exactly like Derek expected: brash, excitable, all unrestrained energy and sure pressure. Derek can barely keep up and it's fun, fun in the way kissing hasn't been since, well, since Page. Derek slows the kiss a bit, deepens it, lets it go on long enough that Stiles pulls away panting, hips helplessly rolling beneath Derek.
"Shit," Stiles breathes out. "Come on. Fuck me. Or let me fuck you. I'm flexible. Let's do this."
Instead of answering, Derek slides down Stiles' body until he's kneeling beside the couch, slowly undoing Stiles' jeans.
Stiles lets out a small groan, audibly swallows, and asks, "So is this, like, a taste thing?"
Derek stops trying to wrangle Stiles' jeans off - made especially hard because Stiles is too distracted to lift his hips to help the progress - and looks up, confused. "What?"
"You know." Stiles flops a useless hand that almost hits Derek in the face. He also chooses that moment to lift his hips, and then makes a frustrated noise when Derek doesn't start removing his pants immediately.
He's not even sure he wants to know at this point, but something in Derek makes him push at one of Stiles' hips to get him to settle back onto the couch while he asks, "I really don't know."
Stiles huffs. "I know taste is kind of a big deal to you guys. It's not a big deal. I'm very much not complaining. About that, at least. About the not-taking-my-pants-off thing? That I'm lodging a formal complaint over."
"Where are you getting your information?" Derek asks, baffled.
"Scott," Stiles says matter-of-factly as he finally gets fed up enough that he shoves his pants, boxers tangled up in them, down to his ankles himself. They hang uselessly off his right ankle after a few unsuccessful attempts at kicking them off.
"And what exactly did Scott tell you?"
"Oh my god. He just said taste was the most important sense a werewolf has. That's why he licks-" Stiles cuts himself off abruptly, eyes narrowing in thought.
Derek can barely tamp down the smile threatening to spread across his face when he asks, "No, finish that sentence. What does Scott lick?"
Stiles nods once, decisively. "I have been lied to. I realize that now. Please continue."
Derek wants to make another comment but gets distracted when he looks over and sees Stiles' cock for the first time. It's barely half-hard, and Derek wants nothing more than to mouth at it, tease it to full hardness and then keep it there until he's satisfied. Stiles' cock visibly hardens when Derek tells him, "Don't come until I tell you to," so he figures he and Stiles are on the same page here.
At first he just licks - a stripe from root to tip on the underside, around the tip, just under the head - until Stiles moans, "Come on. Oh my god, do it already."
Derek lets his bottom lip rest against the head of Stiles' cock so that his breath can ghost across the tip when he answers, "Ask for it."
Stiles sets his jaw and glares at Derek. He's breathing a little shallower than normal, cheeks flushed with arousal - and now anger - and Derek has to pull away and take a deep breath to calm himself a little because he kind of wants to make Stiles look like that all the time and he needs to just slow his goddamn roll. Not that the breath helps much because all he gets is Stiles' pre-come mixed with Derek's own spit and it's inciting, to say the least.
Just as Derek's about to just say fuck it and finish Stiles off (and then maybe finish him off again in Derek's bed) Stiles asks, curious and still just a tad resentful, "This is a thing for you? Begging?"
It's not, really. He really only said it to be a dick. But now he's kind of annoyed Stiles keeps questioning him about his sexual preferences when he could just be experiencing them so he nods and wets his lips for good measure.
"Okay, uh," Stiles starts tentatively, "please actually put your lips around my cock so that I can come in this century."
Derek huffs out a laugh as he begins mouth at the base. He murmurs, "Like this?" against the skin.
He hears Stiles take a steadying breath before he says, "No. You asshole. For the love of-" He breaks off on a moan when Derek finally takes him in his mouth until Stiles is hitting the back of his throat. Derek wraps a hand around the parts his mouth can't reach and sucks lightly.
"Holy shit," Stiles says breathlessly. "Finally."
Derek works his tongue against the underside of Stiles' cock as he strokes the rest with his hand until he hears Stiles' heartbeat spike, feels his thigh muscles clench under Derek's free hand. He lets Stiles fall out of his mouth and pulls back his hand, smirking at the wrecked, indignant sounds Stiles makes.
"Hey, what? You- I-"
"I didn't hear any begging." He wants to laugh at the absolutely betrayed look Stiles shoots him, but he schools his face into a blank look. He even makes himself shrug, like, this is on you.
Stiles lets his head flop back on to the couch and says, "Fine. You know what? It doesn't even matter. I'm pretty sure you've sucked my dignity right out of my dick already anyway. Please, please, continue to do so."
Derek wraps a hand around Stiles again.
"I, uh," Stiles swallows, "I need you."
Derek pauses, mouth hovering inches away from Stiles, because I need you.
It wasn't meant like that. Derek knows that for certain when Stiles adds on quickly, "I need your mouth back on me," but it makes something flare up deep inside him, calls to that instinct to provide that's been plaguing him ever since the party.
When he finally wraps his lips back around Stiles' cock, he can't help but moan, deeply pleased by the cry Stiles lets out. Stiles' back arches off the couch, hips flexing upwards of their own accord until Derek throws an arm across Stiles' lower stomach.
"Oh god, please-" Stiles stops to moan and never finishes his thought. At this point, he never finishes a thought out loud, it's all half-formed sentences and fingers digging almost painfully into Derek's shoulders, white-knuckling the couch cushions, raking through Derek's hair.
He comes half-way through the word please and Derek can feel his cock pulse where it's still trapped in his now too-tight jeans. Begging really isn't his thing, still isn't, but Stiles so willing and eager to please him is really doing things to him.
Derek pushes himself up to kneel on the couch between Stiles' spread knees and starts to undo his fly.
"Nah," Stiles says slowly, motioning for Derek to come closer. "Let me do that. Just give me a minute to catch up."
"Next time." It's not that he doesn't want Stiles to touch him, it's just that he's pretty sure he's not going to last more than a few strokes and he wants to drag it out, really feel every moment of it when Stiles touches him for the first time.
Derek takes himself in hand and it only takes six strokes before he's spilling over Stiles' belly, his softening cock. It takes ounce of strength he has not to collapse right on top of Stiles. Instead, he falls to the side, wedging himself between Stiles and the back of the couch.
Stiles' hand drags lazily through Derek's hair for so long that Derek's almost asleep when Stiles says softly, "One kink down, four hundred to go."
Derek can't help but snort. "Are you still on that?"
"Not obsessed," Stiles says with an indignant noise. "I just think, since we started this, we should see it through."
He sounds completely confident. The kind of confident Derek's heard from him in front of his dad when he knows he's done something wrong, the kind of confident he uses in front of something that wants to see him dead. The kind of confident he used with Derek a long time ago under very different circumstances.
Derek hides his smile in Stiles' chest and says, "I guess I could live with that."