Bonnie and The Doctor in “The Zygon Inversion”

I don't understand how you could just forgive me.

Because I've been where you have. There was another box. I was gonna press another button. I was gonna wipe out all of my own kind, man woman and child, I was so sure I was right.

What happened?

Same thing that happened to you: I let Clara Oswald get inside my head. Trust me, she doesn't leave.