GEMMA: I don't want to execute anyone.

DOCTOR: Good. I don't want to be executed.

GEMMA: I didn't get into this to kill people.

DOCTOR: Neither did I. See, we have so much in common. I mean, you do realise it's terribly easy to avoid murder, don't you? The vast majority of people in the universe manage to go weeks without killing a single person. Months, sometimes. Lifetimes, even. It's mainly lifetimes, if I'm honest.

GEMMA: And how long has it been for you?