“I see where you're going with this, I really do,” Stiles tells Derek, “and in theory, it's hot as hell. But the reality is not. You know why? Because at some point I will get to the digestive system, Derek, and there's nothing hot about the colon. Nothing.”
Derek rolls his eyes and shuts Stiles' biology textbook, which has eaten up most of Stiles' attention tonight. Stiles sort of hates his professor, who happens to be the Chair of the department and therefore does not care that every single person in class is only there because it's a requirement. Stiles is an English major, okay? He doesn't need to know this much about the human body, its workings, or its parts. There should be a Biology For Non Majors option on the schedule; he'd pay extra for that.
“Just skip the organs.”
Stiles sighs, mournfully. “You know those things--” Stiles gestures at his own pelvis, hands tracing out an angled line on each side. “--those groove things you have that I love? I found out what those are called. They're called Adam's Girdle. My favorite thing, and now it's forever synonymous with old people's support garments. This class has killed my hard on for your groove things, Derek.”
Derek makes a face like Stiles is a fun suck of epic proportions and lives to piss on parades or something. Which, no. That's Derek. “Are you actually arguing against me taking off all of my clothes, lying on your bed, and letting you use me as a tactile study guide?”
To emphasize his point, Derek strips his shirt off. He drags his hands down his own chest after dropping the t-shirt, and Stiles maybe drools a bit.
“...well, when you put it that way, no, I am not.” Stiles pushes back from his desk and gives Derek all of his attention. He twirls his finger and wiggles his eyebrows. “Do a sexy little dance when you strip.”
Derek's glare is flat and unamused. See. Fun suck. Except, not, because he might not do a dance, but he does get naked pretty damn fast, and a naked Derek is the absolute opposite of a fun suck. He pulls Stiles to his feet then, and strips him down with a focused efficiency that's not sexy on its own, but is hot as fuck when Stiles thinks about how intent on getting him naked Derek is.
When Derek stretches out on Stiles' bed, Stiles doesn't even know where to look. Derek is fucking beautiful, all defined lines and perfect skin and insouciant eyes. Every time Stiles sees him like this, he's overcome.
“Come here.” Derek holds out a hand. Stiles takes it and lets himself be pulled down on the extra long twin bed he's stuck with in his dorm. There's never enough room for both of them, and tonight's no exception. Derek, though, just spreads his legs and puts Stiles on his knees between them. He brings Stiles' hand to his forehead. “Start here.”
Stiles feels stupid, at first, and his fingers stutter down Derek's face as he awkwardly names bones, muscles, whatever. Until he gets to Derek's mouth, because Derek parts it and uses his tongue to draw two of Stiles fingers in, and the look in his eyes, it's all lazy pleasure and leaden contentment, and Stiles can't resist that. Not even straight men or lesbians could resist that.
A low thrum of arousal winds its way through Stiles, easy and low key, and Derek makes a noise of approval. Stiles relaxes, lets go, and strokes his fingers across Derek's tongue, then pulls back to smear them across Derek's lips, down his chin, across the lower part of his face, murmuring things like, “Mandible, masseter,” at Derek's jaw, and “Orbicularis oris and aveolar process” at the area above his upper lip.
Derek smiles under his fingers, real and simple, and Stiles can't help but kiss him, lick across his lips and into his mouth. Derek just opens up for him, tongue tangling with Stiles'. “Keep going,” Derek tells him, voice like a rumble, and Stiles does.
He traces down Derek's neck, across his collar bone, and Derek nudges him until he says, “Sternocleidomastoid, clavicle, scapula,” and follows fingers with mouth. He breathes heavily against Derek's neck, which does nothing for him but makes Derek gasp, so it turns Stiles on, too.
Stiles goes lower, down Derek's arms all the way to the tips of his fingers--”phalanges”--then down his chest, nails scratching deliciously at Derek's nipples, to his hips--”gluteus medius”--spreading his fingers, pinkies slotting perfectly into that groove. Then Stiles maps every inch of Derek's torso with his tongue, trailing through dips and valleys, scraping the contours with his teeth, and naming all the muscles while Derek trembles and under him.
Stiles looks up. Derek's eyes are glazed over, unseeing with lust and need. He lurches up to take Derek's mouth again. “I love you like this,” he says, then slides back down.
He bypasses Derek's cock, which is lazily hard, much like Stiles' own, and focuses on his thighs, then lower and lower until he's at the tips of Derek's toes.
Derek looks gone, drugged and out of his mind, shaking and arching under Stiles like he's stretching after a nap. Stiles' heart cracks open in his chest, the way it always does when Derek gets like this, pliant and ready, his body completely in Stiles' hands. No one else gets this. No one else has ever gotten this from Derek.
Stiles drags his palms up in the inside of Derek's thighs, parting them, and crouches down. He exhales wetly across the entire length of Derek's cock, the skin of his balls, and Derek braces his hands on the wall behind him, which is pock marked with holes from his claws. Stiles moves his mouth lower, and under his hands Derek's muscles tense and relax in anticipation.
Derek is always first-time tight because of his werewolf healing, and Stiles wouldn't have it any other way. He loves working Derek open and ready, loves coaxing his muscles to give way for Stiles' tongue to get him ready for fingers, for Stiles' cock. Stiles could and has spent hours rimming Derek, taking breaks to rest his jaw and diving back in, because the noises Derek makes—Jesus fuck, the noises.
Little keens, small whimpers, breathless gasps. Derek gives it up so fucking prettily and it's positively addicting.
When Stiles pushes a finger into Derek's ass alongside his tongue, Derek goes boneless. Stiles chances a look up: Derek is staring up at the ceiling, mindless, mouth gaping open, hands twitching at his sides.
Stiles finds his prostate, and Derek doesn't jerk, doesn't convulse the way Stiles does when Derek presses against his. Derek just groans, long and loud, and digs a new set of clawmarks into the wall. His neck arches when Stiles rubs his perineum, and Stiles feels just as drugged as Derek looks, but now he needs to be in him.
The lube is tucked under the mattress, and Stiles gets it out and coats his fingers. He slips two inside of Derek, fucking him open and wide, and sucks on his balls.
“Stiles, oh.” Derek's voice is a sticky slur that causes Stiles to shudder and press another finger in. “Like that, just like that.”
When Stiles lines his cock up and pushes in, Derek just gives around him, slick and easy, open and welcoming, even though he was virgin tight not that long ago, and Stiles bottoms out in one slow glide, breath stuttering out of his lungs unsteadily. “Oh, fuck, Derek, fuck.”
The pace Stiles sets is slow and hard. Under him, Derek undulates, motions like currents in the ocean, eyes burning red, one clawed hand tugging at his cock in time with Stiles' thrusts.
Stiles feels like he could do this forever. He wants to do this forever, because this is a side of Derek that belongs to him, that's kept safe for him and only him. This is Derek giving himself over, letting himself go. But then Derek starts clenching and Stiles isn't going to be able to last long, not with that going on, holy fuck.
“Where do you want me to come?” he gasps. “In you, or--”
Derek comes, then, sudden and seemingly surprised. “Both,” he pants out. “Both.”
Stiles thrusts a few more times, then starts coming. He pulses twice, three times, inside of Derek, then pulls out and shoots the rest of it onto Derek's cock. When he's done, Stiles rubs his come into the skin of Derek's now soft cock, on his nipples, on the sides of his neck and the front of his throat.
Derek growls, feral and appreciative and supremely satisfied. He pulls Stiles down and laves at his entire neck, issuing happy rumbles, and Stiles just shudders and twitches at the overstimulation.
“I hope you know,” Stiles says a while later, voice dry and cracked, “that I'm probably going to pop inappropriate boners during my bio test, and it's all your fault.”
Derek cracks open an eye, stares at him for a moment, and smiles smugly.