Nathaniel stares at them both. His expression may not convey horror, but he is horrified. And angry, and baffled. Baffled is more like what comes across.

"So you want to save all the mages...except him. You want to protect all the mages, but not him. Whatever world you're creating, he can't be a part of it. Because he's a person now without a vengeful, bloodthirsty spirit persecuting him as badly as the Templars ever did. Do you think of it that way? That he was more useful to you when he was hurting?

"You could come to the Inquisition. Sit on the mages' council and help Anders prepare the mages for a life of freedom. But I'm sure he has already told you about that, and you've still done this. And you want us to prove goodwill? You took the man I love and you dare to lecture me on the justice of your cause?"