Sherlock moaned out in disappointment when John pulled out. It was a strange feeling, to feel them man's semen running down his thighs and arse. He hadn't expected John to reopen his cheeks, but he quickly realized that he was checking him.
Of course, he was a doctor. He would do that.

Sherlock was still on his hands and knees, and John was laying on the floor next to him. He had actually forgotten for a moment that he was still achingly hard.

The fact that John was going to let him fuck him even after this made him twitch in arousal.