Jack met the Doctor's gaze steadily. "I might not have shot you on sight, because your face isn't one that I knew belonged to the Doctor. But anyone earlier?" He shrugged. "I would have."
He took another sip of his wine. "The other... In my world, the Master has been the only constant besides not staying dead in my life for a century. And I have been the only constant in his. He doesn't like to give up control, and to have control... not with him. Or an alternate of him." Jack shook his head. "It's enough to throw me."