Vongrak
Okay, yeah I don't know how I couldn't see it. But of course, a demon of passion is better suited for relationship advice than one of knowledge. Now, I don't understand why her being gay is an advantage? Good thing they don't discriminate here though. Refreshing. And the city seems pretty interesting too. I know this isn't a combat arc but if there'll be something interesting, I'd like the arc to be more than the relationship advice.
A couple of reasons. (Oh and spoilers) One is more obvious, Apep's best friend Jara is asexual. The second is because Kat and Lily are in a relationship and can actually go TOGETHER but count as '1 demon' for Apep's price range. Then there's the fact that, not that we know yet, Zurha the love interest was raised in an orphanage. Those are just some of the reasons Kat is a good choice for this.