"Stop that. I'm not leaving you. I did that once, never again, remember?"

The Doctor pulled Jack into a hug, then, wrapping his arms around his shoulders firmly, while trying not to shift his upper torso too much. He held him close.

Holding him like this, he hoped, could cover up the incredible relief he knew his face was betraying. When Jack didn't come back, he could feel the timelines snapping back, but he wasn't sure. Wasn't sure it would work this time, too. Maybe, in this world, Jack wasn't able to reform. Maybe he needed the TARDIS, maybe---well, just maybe.

Having him alive and insisting the Doctor leave, well, that was a hell of a lot better than having him the way he was before.