In any other instance, Jack might have been delighted to have the Doctor kiss him. But this... This was different, and he wasn't entirely sure that he was okay with it. There was a sort of... pulling from inside him, though he couldn't exactly pinpoint where it was coming from, but it felt like his very marrow was being drained. The breath was stolen right out of him, though not necessarily in a good way, and it left Jack feeling properly scared for the first time in a very, very long time.

It was actually Jack who pulled away, clutching his chest and panting. "What the hell was that?!"