The both of them must have a deep reservoir of lust that has been filling steadily while this case has had Holmes's attention. He's too happy to drain it now, too happy to give himself over to feeling eager and lustful and hungry and reckless. They really are made for each other; their remarkably excellent sex life must be a result of that. Their tastes would not mesh so well, their bodies would not answer so strongly to one another if Nature hadn't pricked the two of them out for each other.

Somehow he manages to draw his hands away from Watson and ready his cock, and he takes hold of Watson's (good) leg, hitching it up around him, before he thrusts into Watson. It's a familiar feeling in the most remarkable way; his muscles know Watson's, understand them, and so he can fluidly begin to rock against Watson as soon as his cock settles inside him.