Depends on the demon. Lesser demons are more animalistic. They hunt, they eat, they survive. You won't find anything terribly complicated there. And ideally, that's where we start.

[ The implication here being that if this does go well, they can work their way up to more powerful quarry. Whatever might sate her. ]

I've yet to see a demon who looks as human as you do, but the more powerful ones are definitely more humanoid, in look and intelligence.

But in either case, it's the hellfire that will be the problem.