The Doctor jerked back from the intimate gesture. It was something he reserved for companions and lovers, neither of which had been part of his life for a long while. But it came naturally to Jack. Not a slap or a shove, but a gentle touch.

If the Doctor were a genius, which he was, he would think that such a touch would be a sign that he'd known Jack, as a friend at least. Feelings were difficult things to rip away with a temporal distort, but if Jack was a fixed point, it might've lingered.

It would explain the sonic and the lapel pins. Well, not explain explain, but it would at least give them an idea where to start.

"Options," he said. "We need options and theories. Who could do this, first off, then why."