The Master smiled ruefully. "This place is really getting to me," he admitted. "I don't know how much longer I can take it."
He lifted an eyebrow, eyes gleaming. "I don't suppose your Master would agree to you being my full-time babysitter, would he?"
And it showed just how far he'd gone that he felt able to talk to this Doctor so openly about these things. Though punching the living daylights out of someone did tend to be a pretty effective ice-breaker.