[This is why he needs Rose around to filter him. Though why does he hide the fact that he's not? Self prevention mainly; still feeling like an endangered species; even in the multiverse. The Doctor doesn't answer her question about him not being human. Maybe she'll forget. It is curious that she even picked that up]

Oh, I'll be fine.

[Then pauses for a moment when she mentions how aliens always trying to take over the Earth- which is another reason to not bring what he is up. Better to blend in even if in a crisis someone just screws his own rules]

You are?

[Then seems to be eyeing her more closely; she doesn't seem to be traumatized or if she is hiding that very well]

What do you do when they come?