This is a phenomenon Teren can barely begin to comprehend, but she at least is able to recognize how close it is to Anders. How wound up in his experience it's been, as deception has been in hers.
She listens quietly as he explains, resisting the rather unusual urge to put a hand on his shoulder. People change through torture, but to have their entire personality stolen away in the blink of an eye? That's... monstrous.

"I'm sorry," she says, a bit stiffly, for lack of anything meaningful to say. It's too big of a thing, she doubts any words can soothe it.