Moriarty and Sherlock in “Unfinished Business”

Your letters have meant a great deal to me. I find them influencing my decisions in the most surprising ways.

Sherlock

You could have killed Agent Mattoo. And from your perspective, it would have been the expedient thing.

And yet, to you, it would have been repugnant. Tell me, is that how you learned to be one of them? By learning to care how your actions seemed in the eyes of another?

Sherlock

I'm not sure I am one of them.