"That... was... amazing," he says in the back of an innocuous black cab, somewhere in the middle of London and on your way to a crime scene as usual. You've just finished describing how you know everything about this man without him having told you – his brother's drinking, his military career, his entire family situation – and now, instead of being defensive or angry or embarrassed, like most people are, he thinks it is amazing.

You confess yourself completely thrown.

"You think so?" you ask, allowing him some wriggle room in case he wants to change his mind. Or expand on his previous statement. Or yell at you to keep out of his business.

"Of course it was, it was extraordinary, it was quite... extraordinary," the man continues. The man. Doctor John Watson. Whom you met yesterday and now seem to be sharing a flat with, if he decides that he indeed wants to. You've never flat-shared before. You've never been called extraordinary by someone who barely knows you before, either. Or by someone who does know you, to be honest.

"That's not what people normally say," you say, turning away from him to hide your surprise.

"What do people normally say?" he asks.

"Piss off," you reply with a wry smile, and are treated to the ghost of a grin beginning to appear on the man's face as he turns to look out of the window.

You aren't sure, but you think you've just successfully made someone laugh.

There seem to be quite a lot of firsts happening today.