They had this conversation about what she'd do with hypothetical magic powers, way early on, and she said some things that came off like... I'm not sure how to put it into words.

But he doesn't have to: he shows her Trouble's memory of the conversation, Trouble's resigned hypothetical fear at his new friend's avowed willingness to rid the world of pain even if not everyone would be okay without it. (Trouble is used to being in love with people who would do terrible things to him if they had a reason that looked good to them; Trouble is also in love with Ethan.)