It was then that he let his hand slide down a little too far, and he noticed for the first time Holmes's growing erection. It was perhaps inevitable, but he hadn't exactly aimed for it, either. His hesitation was only momentary, and had more to do with surprise, with savouring this moment and the power he had.

For Watson, there was no question of what the proper reaction was in this situation.

He reached down and took Holmes's cock in his hand, shutting his eyes at the feel of it. It had been far too long, he thought, since he'd had any cock in hand other than his own. He pressed his lips against Holmes's neck, exhaling slowly.