He slinks to his knees just like that, rough denim on rougher ground, looking up at Derek with that fucking smirk showing in his eyes and his long, distracting fingers tugging at Derek’s belt, nightstick tapping him on the thigh with the motion, metallic tap of his cuffs.
“Finally gonna let me?” Stiles – if that’s even his name, christ – asks, sweet innocence as artificial as the stuff Derek dumps into his coffee. He’s got his hands on Derek’s thighs now, spanned out and squeezing the outline of his muscles, pushing his fingertips under the leather of his belt, framing his dick that’s gotta be showing so damn obvious, damning. Like he’s not damned already standing in a lousy patch of shadow on an even lousier street, with this… this kid who’s almost certainly underage no matter what his fake ID or his height or the lean muscle packed under his threadbare tee might say. Like he hasn’t been jerking off every night for weeks thinking about Stiles’ mouth or his hands or the bulge of his cock when he lets Derek feel it in some power play of a taunt; about the pale, mole-dotted skin that’s not always showing through the holes in his shirts.
“Fuck,” he grits out, all air and scraping consonants. “Yeah, just. Do it.”
Stiles grins then, and like a flash he really does look young – really is young, and it’s so easy to forget when Derek’s stuck between wanting to book him or kill him or get him spread out across his bed on any given day. He gets Derek’s belt open, and then his pants, heat of his hands seeping through Derek’s briefs and the swipe of his tongue across his bottom lip, the wet knock of it against the ring glinting just off-centre is the filthiest, prettiest thing Derek can remember seeing.
He makes a helpless little noise when Stiles pulls his cock through the slit in his underwear, cool air jolting up his spine and the faint trace of Stiles’ breath on the damp head turning his toes into a painful clench inside his boots.
There’s the tiniest murmur of, “Fuck yeah,” out of Stiles’ lips before they’re a slick O wrapped around Derek’s dick, tongue flickering and the hard nudge of metal on the flat middle turning Derek’s knees to jelly. He sucks down his length with his eyes fixed up on Derek’s lashes long and batting when he blinks, strands of bright-coloured hair clinging to his sweaty temple. His hands pull Derek closer by the outside of his thighs, mouth burning him alive and tongue flaying him down to his bones.
Under the sopping pull of all that suction and the sweat pooling low on his back, sticking his uniform to him, Derek’s lit up by just how much they shouldn’t be doing this, and there’s heat in his face and low, desperate groans falling off his tongue because it’s excitement and not guilt, brand-hot want wrapping its way around his chest.
His hips twitch forwards, push his cock another inch towards Stiles’ throat, and Stiles makes a needy whine, another when Derek does it again on purpose.
Christ, this kid.
The ball of metal on Stiles’ tongue digs under the head of Derek’s dick, sharp, electric rattles making Derek fuck into his mouth over and over, Stiles sucking harder with his blotchy flush filling the hollow of his cheeks, spreading down to his neck and under his collar.
Derek’s fingers slide over the side of Stiles’ head, tips itching with the buzzed prickle either side of the dyed and longer spikes. He cups the back of Stiles’ skull, guides him with easy pressure when he slides his lips back to the head and then down the shaft again and again, brief flutter of his throat.
He can’t stop himself thumbing at the ring on Stiles’ lip, pushing spit and his own precome around the obscene pink-bruised swell of Stiles’ mouth. He doesn’t want to know where Stiles learned to do this, or who with, or how long ago, but the fleeting consideration makes him grind into Stiles’ mouth deeper just the same, like he can fuck the taste of some theoretical other guy out of him.
Derek’s got no fucking clue how it got this far, between him getting lured into verbal sparring with a smartass kid and the time when he started looking forward to it, between handing out warnings and Stiles taking them like they were lotto tickets. Between Stiles being no one and then Stiles being someone Derek couldn’t stay away from.
Stiles’ fingers dig into his ass and yank him in, throat gripping and fluttering around the head and metal digging over veins, eyes wet with tears that make him look dangerously younger and so beautiful Derek feels it like a shard of glass between his ribs, frenetic energy and stupid want written into every line of him.
He couldn’t hold off coming if he wanted to, pulsing and twitching in the sucking clench of Stiles’ mouth and over the pillow of his tongue, head snapping back between his shoulders and his hands gripping Stiles’ head, his cheek where Derek’s cock is a swell beneath his skin.
Stiles drags his orgasm out of him, every last aftershock shooting out through his hips and into Stiles the way lighting goes to ground.
The air’s chilled when his half-hard length slips out from Stiles’ lips, Stiles ducking down for one last lick over the head with a cheeky smirk on his ruined, fucked-out mouth. Derek grunts as he hauls Stiles to his feet by the shoulders, pushes him back to the wall again and drives his tongue into Stiles’ mouth, groans at how hot his lips are, how swollen they feel.
Stiles’ hips twitch into his, helpless and graceless, and Derek’s maybe wearing his own smirk when he ruts hard into Stiles’ body, drags his hips over the ridge of Stiles’ dick in his jeans.
“You’re so close,” he says, like a taunt, and Stiles whimpers, breathy panting smudged into Derek’s cheek, his mouth. “Gonna nut yourself like this? Come in your shorts like a kid?”
Stiles head knocks back against dirty brick and his pretty mouth hangs open as he comes, and Derek can feel it, the way he goes tight and then abruptly loose all over, the tremble chasing jagged down his limbs. When it’s over he slumps forward into Derek, heavy and pliant and setting light to some protective fuse in Derek that he didn’t even know was there much less knows what to do with.
“You gonna arrest me now?” Stiles mumbles, like he’s been gargling with sand and still sounding less than cogent, random shakes brushing his chest against Derek’s.
“Little late for that,” Derek tells him, hand on Stiles’ back keeping him from braining himself against the wall, other hand on his hip holding him close. “No offense but I don’t want to share a cell with you.”
Stiles’ snort puffs into the curve of Derek’s neck, precedes the nip of his teeth and the flick of his tongue. Little shit.
“Gonna make me walk home like this?” Stiles asks, and his tone’s different but Derek can’t place how or why. He can guess, he just doesn’t want to. He can only look down this path so far at once. “After you made me jizz my pants?”
He’s got no idea where Stiles lives, if he’s got parents or roommates or what.
“My apartment’s a few blocks from here,” he says, one giant middle finger to every last better instinct he has. “You can clean up there.”
Stiles’ eyes are dark when they find his, pick over his expression like there’s something under it. “S’that all?” he asks, one eyebrow quirked into a dare, a tease.
Derek leans in and kisses him, really kisses him, takes him apart with scrapes of teeth and the path of his tongue, opens Stiles’ mouth for him to lick into.
“Don’t push your luck,” he says, fingers squeezing on Stiles’ narrow waist.
Not for the first time, or the tenth, Stiles’ lips curve into a smile when he says, “That’s not a no, officer.”
ETA: There is now a second installment in this ‘verse here