She's also not human, but he doesn't mention that. Seems like she's something she's keeping on the down-low. She can come out, or into it, on her own time. At least whenever she feels like revealing it to Jack. That's the complication right there.

"Yet." He's frankly sure he's gotten too close to that. "And what happens to my brain if yours goes?" It's a low blow but maybe if Istredd isn't only thinking of his own well-being he's more likely to take care of himself.