He's hit a nerve, obviously, he doesn't miss that particular cue, at least. No doubt the Doctor himself would feel a similar sort of way, and he has. But—good, he thinks. Best to get it out. He respects the need to keep secrets, he won't betray anything Wrathion's told him, but there's no need to hide from him, either. Everyone just needs to see it his way, of course.

"And what we know will be kept safe," the Doctor adds to reassure. Though, perhaps little comfort. "And you, your kind—are you all that's left?"

Though the question is asked with care, with a gentleness of tone, the Doctor isn't unaware that it's still intrusive and likely not altogether comfortable. It's not a subject he particularly enjoys himself, yet if he's at all correct, in some fashion perhaps they would share an understanding in this.