Jamie stared. He almost couldn't believe what he was looking at, only he had been travelling with the Doctor long enough to know that bizarre sights were to be expected. Even, yes, the sight of the Doctor and himself, clinging to and kissing each other, and was that the Doctor's tongue he saw in the other Jamie's mouth?
His own Doctor tugged at his arm, pulling Jamie away from the scene.
"Who were they, Doctor?" Jamie cried.
"Versions of us from a parallel universe," the Doctor explained briefly.
"Evil ones?"
"No, not evil."
"Then why were they carrying on like that?" Jamie gestured feebly.
The Doctor sighed. "Because they're together, a couple, in their own universe. I'm sorry you had to see their behaviour, Jamie. I know it shocked and upset you."
Jamie hesitated, then said, "I have just the one question. Why aren't we doing what they are?"