A flexible moral code is useful in your line of work.

[But that won't save him from Moriarty and his brilliant insanity.]

The difference between you and he, Sherlock, is that he would murder an entire city just to keep you running. You must admire his tenacity at the art of causing pain. He's a perfectionist.

[She searches out his eyes, for a moment.]

He will stop at nothing to win.