[His eyes grow colder.] The situation changed. I told him what he needed to know in order to understand just why Rose and I reacted the way we did to his presence here. Which is to say, we were completely and utterly bewildered.

I can't tell you anything more than that. [His voice softens.] You'll know when you get there.

Paradox? Maybe. But his being here is a paradox in and of itself, Doctor. As is yours. As is a lot of this place. I don't even know if that's our Jack You looked at his records not too long ago, after London. You know that they don't account for his time here. Nor does this place exist anywhere in the TARDIS' computers.

And for that matter, I don't remember ever being here before. If you're me, what does that mean?