The Bride Wore Black: Well that was a helluva shock.
I particularly liked this bookend..
Doctor to Nicolette: "You know I've changed too. I've become a healer instead of a destroyer. And that's why I'm so sorry for what I have to do. But it's for the greater good."
Letter written by the Doctor, purporting to be Nicolette's note: "I told myself I was acting for the greater good. But that kind of thinking leads you down a dark road."
I know the Doctor said Nicolette was using the greater good as an excuse but I think she fully admits here to using it in the same way, and she wonders where her own choices will take her.
Then Nolan had a line at the end that someitme good people do bad things.
I'm going to miss Nicolette though, I was starting to like the mean old bag.