That entire scene was the best Mycroft ever.

"...she was John's therapist."
"Shot me during a session."
"Only with a tranquilliser."
"Hmm. We still had ten minutes to go."
"Well, we'll see about a refund."

I loved John saying "the deduction thing" and Mycroft repeating it with a little wiggle.

Here are mine :

Moriarty : Welcome to the final problem.

Sherlock : Hey, bro !

John : There's a place for people like you, the desperate, the terrified. The ones with nowhere else to run.
Mycroft : What place ?
John : 221B Baker Street. If there's a queue, join in.

Mycroft : Every choice you ever made, every path you've ever taken, the man you are today is your memory of Eurus.

Mycroft (BAMF !!) : For your own physical safety, do not speak. Do not indulge in any non-verbal signals suggestive of internal thought !

Mycroft : I presume the tapes are in my office ?
Governor : Your office ?
Mycroft : Cast your mind back. Used to be yours.

Sherlock to Mycroft : Do shut up, dear.

Sherlock : He's trying to make it easy for me to kill him.

Mycroft : I promised my brain to the Royal Society.
Sherlock : Where would you suggest ?
Mycroft : Well, I suppose there is a heart somewhere inside me. I don't imagine it's much of a target, but why don't we try for that ?

Mycroft : Goodbye, brother mine. No flowers. My request.

Moriarty : Holmes killing Holmes.

Mary : PS : I know you two. And if I'm gone, I know what you could become. Because I know who you really are. A junkie who solves crimes to get high. And the doctor who never came home from the war. Will you listen to me ? Who you really are, it doesn't matter. It's all about the legend. The stories, the adventures. There is a last refuge for the desperate, the unloved, the persecuted. There is a final court of appeal for everyone. When life gets too strange, too impossible, too frightening, there is always one last hope. When all else fails, there are two men sitting arguing in a scruffy flat like they've always been there, and they always will. The best and wisest men I have ever known. My Baker Street boys. Sherlock Holmes and Doctor Watson.

Sherlock: "...you two, Wiggins has got your money by the gate, don't spend it all in one crack den."