Derek wants more than the occasional frantic fuck that Stiles slinks away from afterwards. They've never exchanged promises though.
Stiles pushes him to his knees and Derek licks his lips. Stiles smells amazing and Derek groans at the first taste of him. He fondles Stiles' balls, taking as much of his cock in his mouth as he can. Derek must slow somewhat because Stiles thrusts, almost making him gag.
"Do that again."
Stiles doesn't need telling twice and the forcefulness is getting Derek hard. It feels fantastic to just take it.
"So good, Derek. Get me ready to fuck you."