He laughs, a weak sound, and he doesn't really know where it comes from. The idea that someone wouldn't want to live with Watson -- that Watson would be so unpleasant a person so as to drive away lodgers -- is just ridiculous. He is Watson. He is considerate, and caring, and compassionate; he is everything that is good, and it hits him that Holmes might have alienated him forever. His laugh breaks, and he presses his hand to his mouth to stop anything else from coming out as he skirts his eyes away from Watson.

"Lying is still not among them," he says, trying to recover himself, but something cracked in him that he isn't sure he's going to be able to repair so easily. He takes a breath and exhales slowly, avoiding Watson's eyes.

"Are you certain I wasn't your worst habit?" he asks quietly.