“Mmm, regrettably, yes. Can't see why I'd want to, waste of time, but if I'm going to I should at least hope I'd not be crap at it – but seven years, nothing to show for it? No, you've nothing to worry about, I'm a hopeless murderer,” Sherlock responds drily.

No, whatever anyone else may think of him, he's no killer. Death interests him, killing doesn't; the two are perfectly distinct, contrary to the implications of his classmates. So, no problem, and he smiles that utter lack of need for concern down on John as they reach the stairs and begin to climb.

“Never snogged someone in a broom closet either, for the record.” Or anywhere else, for that matter, but that much is probably obvious. Sherlock can't say it concerns him. “You are distressingly safe, probably. Make it up to you some other way.”