Character ruminations/fic rec: WtNV/Dresden Files: "Love Is All You Need [...]"

Anyone want to talk characterization? I'm trying to figure out why a Welcome to Night Vale / Dresden Files crossover fic grabbed me so hard, because there are elements of the characterization of Carlos that I didn't think were really my thing, but they definitely work for me here. This is mostly just me trying to work something out for myself, so feel free to skip, but I'd love to chat about this stuff if anyone is interested.

The fic is Love Is All You Need to Destroy Your Enemies. I'm a fan of WtNV, but I don't know that I'd say I'm a hardcore fan or anything; I've never read "Dresden Files", and haven't really planned to, to the point that I've spoiled myself for numerous series developments. (I'm sure it's fine for the folks who like it; I don't mean to slam it or anything.) I try to avoid actual spoilers for the fic here, but there are some vague premise-and-characterization spoilers in my ramblings. ( Cut for rambling ... )