Imagine after he shoots Magnussen, Sherlock is anxiously washing his hands and face, then looks up at the mirror in front of him and all he can see surrounding his reflection is the word ‘murderer’.
And then a short while later he sees John who turns to him and smiles a sad but comforting smile, and all Sherlock sees surrounding John is the word ‘safe’
"I hope," said the lady, "that you have not come to cross-examine me again?"
"No," Holmes answered, in his gentlest voice, "I will not cause you any unnecessary trouble, Lady Brackenstall, and my whole desire is to make things easy for you, for I am convinced that you are a much-tried woman. If you will treat me as a friend and trust me, you may find that I will justify your trust."