John was one of the few who was not attached to anyone. He had fought hard to keep himself free of attachments. "You don't have to sir..." he said after a moment, flushing.

He lifted his hand and carefully pushed Sherlock's cock up. He pulled the foreskin back just enough to clean under it, taking care not to miss any part with his tongue. Once that was finished, he lowered his hand and released him.

He returned to licking along his length cleaning him, making a soft noise as he did so.