"Am I?" the Doctor says, his eyes wide and manic. "You've figured out what she means to me, Master, and you know I'd rip the universe in half for someone I care about."

He leans in, his voice cold as ice.

"And I can't kill you in that cell, but I have a TARDIS with a chameleon circuit. And a human can't tear a hole into anyone's mind. Course, they also get older, have lowered strength, constitution..." He straightens. "Your choice. Right now."