"Personal business," the Doctor repeated. His eyes roamed over the Master's...current condition, plus handcuffs. "Master of the obvious, you! Very personal, I'd say."

He could leave the Master here for however long it took for him to figure out a way to free himself, as if that would teach him a lesson. Ignoring the fact that the Master was trying to burn holes right through his forehead, the Doctor pretended to inspect the armrest of his chair, picking at it with his nail and knowing that he'd have to try to get the story from River at some point, make sure she wasn't....damaged. It had probably been only a matter of time before the Master picked up what an annoyingly interesting woman River was and decided he wanted to know more, taking rather than just asking. He couldn't say he wasn't disappointed and angry at him.

After all this time between them. All those centuries. And here they were, back where they had been lives and faces and countless friends and enemies later!