Responses

and the prince has been slowly losing his mind and consumed by like, i couldn't really tell
Leshek loses his ability to feel anything, physically or emotionally, without emotions to empathize, his obsession (which is part of the curse, that's why he's so taken with him from the jump), drives him to be able to commit any atrocity. Once he restores his ability to feel he goes back to being green.
I read the book so if anyone needs spoilers hmu