Ride him.

Billy moves Strange upright, spreads his legs with blue magic, and parts his ass cheeks just enough. He lowers Strange just enough to hover on the tip of his cock, teasing him just enough. Arousal betrays Strange's apprehension. He's pretending like he doesn't want to do it--and is only letting Billy do it out of necessity for the study, but Billy can feel--and see, as Strange's pale cock rises to attention--Strange's desire. He lifts Strange up, giving the split-second relief that he changed his mind, then drops the magic.

Strange plummets right onto Billy's cock, the teen's large organ stuffing him to the brim all at once. Strange tilts back his head, howling gasping with moans of pleasure and pain and shock. Strange struggles to catch his breath, staring at Billy through wide, exasperated eyes. Strange's entire face trembles with the pain and pleasure, his jaw slack. His hand lands on Billy's chest and he holds onto the teen's pecs for support.

Magic encases Strange again, forcing him up and down at blurring speed. Strange's gasping howls turn into yells and roars as his prostate is demolished and his tunnels are stretched open with apathetically brutal speed. Billy's entire body pounds into Strange with pleasure coursing through Billy's lean body. He feels the meaty, tight elastic inside of Strange's body pulsing and throbbing, slippery friction at boggling speed.

Strange gasps, "Wait--stop--I can't--I'm gonna--"

Strange cums, and his jizz squirts all over himself, making him look even more like a horny slut of a distinguished surgeon.