Dam, Thistle is pretty badass to turn a demonic genie's power against him, since we know that it's usually the demon that turn against its user after they gain enough power from desire
I was so on board with the Winged Lion (Demon) being evil but now I'm questioning it again. It sounds so rational, just told Thistle that it shouldn't be all gloom and doom (give them a festival).
And although it did seem like it was tempting Marcille...what if what the Demon wants it for everyone (including the demon/dungeon creatures) to get along. Her wish for everyone to live the same amount of time does sort of coincide with the Demon's true desire.