Always stick to the story. It was when you started backtracking that people got in trouble. Interrogation 101.

Until you guys own your own souls you don't own mine. Until you guys can be trusted every time and always, in all times and conditions, to seek the truth out and find it and let the chips fall where they may— until that time comes, I have the right to listen to my conscience, and protect my client the best way I can. Until I'm sure you won't do him more harm than you'll do the truth good. Or until I'm hauled before somebody that can make me talk.

I get it,' said the prisoner. 'Good Cop, Bad Cop, eh?'If you like.' said Vimes. 'But we're a bit short staffed here, so if I give you a cigarette would you mind kicking yourself in the teeth?

No! Please! I'll tell you whatever you want to know! the man yelled. Really? said Vimes. What's the orbital velocity of the moon?What?Oh, you'd like something simpler?

...because love is continual interrogation. I don't know of a better definition of love.