" He obliterates things, she realized. He shatters them. They think they've won because he's a bit vague and he waffles, but that only goes so far. It's his shell, like a tortoise, if a tortoise was soft on the outside and dangerous on the inside. That's how the Time War ended: he got to the bottom of his patience, and he took two entire civilisations out of the universe and lock them away, and one of them was his own. That's how sharp his sense of obligation is.

And he lives like that. He does it all the time. "

― Nick Harkaway , Doctor Who: Keeping Up with the Joneses (Time Trips)