Stiles still can't believe he's allowed to touch. His fingers move slow, barely skimming the skin over Derek's collarbone, because what if he scratched? Derek might take this away.

He's almost vibrating with restraint. His lower lip drags on the curve of muscle between Derek's shoulder and throat, his tongue darts out to taste and, oh, god. Derek is warmth and salt and so good and it's not enough. Stiles' breath catches, shudders, his fingers bite down as he barely stops himself from sinking his teeth into Derek's skin.

Derek goes stiff beneath Stiles' hands. A low rumble shakes his chest, a growl that Stiles can feel but not hear. "Sorry," Stiles says, pulling back, dropping his forehead to Derek's shoulder, pulling his hands away. "I... I—"

"God, Stiles," Derek says, his hand coming down on the back of Stiles' neck. "Don't stop."

There's corded muscle under Stiles' lips, the pulse jumps in Derek's throat. "Are you gonna kill me if I bite you?" His fists clench on Derek's shoulders as he tries to keep his nails away from the skin. He wants to hang on, to dig in and really feel the flesh under his hands and mouth. He opens his lips, flattens his tongue over the pulse, fights the urge to sink his teeth until his jaw aches.

Derek shivers and arches beneath him. "No. Are you—?" His hips roll, pressing up, sweat slick between them. "Do it."

Air rushes out of Stiles' lungs. He gasps for breath, digs his toes into the mattress, and rocks down. He groans, the sound muffled with his mouth locked to Derek's throat, then he can't not. His teeth sink into hard muscle, his palms flatten over Derek's biceps and his fingernails dig in, deep. Skin peels away.

It's good. He holds on, with his teeth and his nails, Derek stiff and shaking beneath him. He grinds his hips down, slow and rolling and pure instinct, driving Derek deeper into the bed with each thrust.

Mine, he thinks. Never letting go.

Derek lets out a small, bitten off whimper. He gasps, sucking air in quick gulps, then goes still and silent as warm, sticky wetness spreads between them.

Stiles groans, tastes blood as he tears at Derek's throat, licks at the indentation his teeth leave behind. His fingernails drag down, scratching audibly at the skin, until he finds Derek's hands and interlocks their fingers. He presses them into the mattress, either side of Derek's head, and he moves.

"Come on," Derek says. "Come on, Stiles."

Something twists in Stiles' chest, something painful and sweet that squeezes his lungs so he can't breathe. He chokes on it as he moves while Derek's strong thighs bracket his hips.

He can taste blood in his mouth, can feel Derek's skin under his nails when he comes.

fin