When Stiles' first rut hits, it's twenty minutes into his chemistry class, and Harris has given him the stink eye a dozen times already, making snide comments about Stiles' inability to sit still.
It's technically nothing new, just the same old same old he's been hearing since kindergarten, but this time, Stiles isn't bored, no. He's overheated and itchy in an undefinable way, his soft dick a no-good aching weight between his legs.
His knot pops without any warning, without any stimulation, making his dick go hard so fucking fast that Stiles gasps out in pain and curls down over the table, clawing at it as he spreads his legs to make room for his knot.
"Dude, you okay? Stiles?" Scott asks, grabbing Stiles by the shoulder, and Stiles jerks away from his touch, falls out of his chair with a snarl.
He's not entirely clear how he makes it from the school to Derek's loft, everything blurred out by the need to touch Derek, to get in him.
"Let me in," he pants with his forehead pressed against the door. He gave up on pounding against it a while ago but fuck, fuck, he knows Derek's in there. He can smell the heat on Derek, the earthy-sweetness of it, and Stiles needs to get between his legs, taste him, see if he's already open. "Derek. Please. I know you're wet already, ready for me, and I wanna--"
The door rolls open abruptly, and Stiles flinches in surprise, stumbling back, but Derek grabs him by the shirt, yanks him inside.
"A fucking carrot makes me wet the right time of the month," Derek snaps, naked and flushed and looking fucking pissed off as he walks Stiles backwards to his bed and shoves him onto it.
"It's not time for your heat," Stiles croaks out, his throat parched and hurting with it. His hips roll up up helplessly when Derek straddles his thighs and unbuckles his pants. "That's not for another two weeks. This is just because of me, for me--"
"Shut up," Derek says, lifting Stiles' dick out and cradling it in his hand, his fingers flitting over the sensitive, too tight skin around Stiles' knot.
Stiles chokes on nothing, need blazing through him, and he tries to sit up, to roll Derek over and--
Derek shoves him back down, wrapping one hand around Stiles's throat in warning while he starts to squeeze Stiles' knot with the other. Stiles cries out and slams his eyes shut, tears leaking out because -- it's too much, to be touched there, Stiles can't--
"There's one thing you can forget about, alpha," Derek says, leaning in and whispering into Stiles' ear, "and that's omegas just rolling over for you. Any omega knows what they want and need--"
"--And if you're lucky, they want to make some use of your knot."
"Please! Please, please let me--"
"I'll make you come now," Derek says, squeezing down harder on Stiles, twisting his hand, and Stiles sees stars. "And then we'll see if you can be good for me. If not, I've always got my toys."