Sherlock shuts up. In and of itself it’s probably a small miracle, though it isn’t as though he’s thick enough to push the issue right now, chatty or no. He does still watch though, watches intently with his lips pressed shut and his fingers twitching nervously at his side.

There’s something wrong here. Or something completely new, at least. He isn’t certain how he ought to feel about it.

And then the words. “Yes,” he rasps, and clears his throat softly.

“It’s fine. If you want to, I mean.” The pause isn’t even very long this time. “It’s not fine, not a bit, but I’d understand.”

No, he wouldn’t.

“No I wouldn’t. It’s… you can. If you like. I won’t stop you.” He’d only want to, desperately.

There’s something he should be doing here, he thinks. Something to demonstrate preference. Touch John’s shoulder, perhaps; is that what people do? Brush some molecules of themselves off onto someone else, leave a few cells behind to mark their passage?

Sherlock has never in his life been bold enough for any such thing. He isn’t now, either. Not half good enough to get away with it besides.

“Should I not have said that? You can forget it if you like; I don’t mind.” And if it's all a bit much to take in, well, it's also a bit hard for Sherlock to breathe.