Martin Freeman (Watson) has said that when Sherlock and Moriarty are together, his job as an actor is to get out of the way. So how does Moriarty actually regard John Watson?
AS: Oh, he’s absolutely on his radar. Moriarty has an obsession with Sherlock, but that means the detective’s best friend is always going to
cause some sort of stirring of strong emotions. There’s a scene in the final episode where I wanted to be able to show that in a small way what Moriarty’s attitude to John is. I think it’s one of restrained respect, but also one of envy. Because Moriarty is a sociopath, I think there is something he doesn’t fully understand about friendship. He doesn’t have any friends himself, and that’s what separates him from Sherlock.