I think it is notable that Ameri and Henri never gave off the vibe of wrath (or destruction for the sake of destruction). In contrary, their "romanticism" or "make-belief" power almost seem equivalent to human compassion. Heck, I don't think we as readers have even seen Ameri in an evil cycle (I bet that would be interesting arc). In fact, we could go all the way back to when Iruma sat down with Henri for a quick talk and Henri guaranteed Iruma's safety - if he was human.
It's almost like they're the good respectable humane demon protecting the humans at their border instead of the shi*show we have in real life with humans acting out as demons on other humans.
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On another note...
Given my understanding about demons and 7 deadly sins, I think the "temptation" is more of an exchange or "deal" between demons and humans. Wrath, Pride, Greed, Lust, Envy, Gluttony, and Sloth. A deal with a demon always seems to stem from a want that is beyond "the norm" and into a never-ending feedback loop. Perhaps demons are just the imaginative embodiment of the unrestrained desires for sinning. On the flip side, there are angels who have only made a brief appearance with a princess representing them from ways back... I wonder what their agenda is.