Mycroft: You must be learning a great deal from him.
Watson: I am.
Mycroft: How else would you put up with him?
Watson: Uh, I don't put up with him. We get along, basically. He's a friend.
Mycroft: Sherlock doesn't have friends.
Watson: Yesterday I would've told you he doesn't have a brother. But he does.
Mycroft: Does he?
Watson: He's changed a lot.
Mycroft: People often say that about addicts, don't they? "He's changed, he's better now." Sherlock is addicted to being himself.