so dao's that goddess astaroth she mentions in the last ep right? bc i googled it and its another male demon god who's name comes from a goddess's astarte. the symbol on the cave is astaroth's + she's clearly linked to the cave, keeps leading ppl back there. (i don't see why else they'd mention the name at the end.)
also found these on her:
Astaroth (also Ashtaroth, Astarot and Asteroth), in demonology, is the Great Duke of Hell in the first hierarchy with Beelzebub and Lucifer; he is part of the evil trinity . He is known as the chaos god of time and space.
dao's go to method for messing w ppl is by pushing them into an endless loop. its also interesting that she's supposed to be part of some evil trinity along w another demon that appeared on this show: beelzebub.
According to Sebastien Michaelis, he is a demon of the First Hierarchy, who seduces by means of laziness, vanity, and rationalized philosophies. To others, he teaches mathematical sciences and handicrafts, can make men invisible and lead them to hidden treasures, and answers every question formulated to him.
so that explains why she uses art to draw ohm and chai in, while apparently 'helping' off. she also clearly just explains whatever her victims ask her, explaining the cycle to pink and telling off the supposed exit. she kept asking chai about om disappearing, and brings up the cave repeatedly talking about it like it's a national treasure. another thing about how she picks her victims is that they're ppl who've rationalized their actions, who continue to think they're not wrong and its the fault of others or a mistake.
leading ppl to the cave must be how she gains sacrifices from humans. the two girls she brought here in the beginning? they must be her victims too and its not that she sacrificed them and got out like some have interpreted. bc like she said, there's no exit. this cave belongs to her, only she can enter and exit. she calls off the 'chosen one', then marks him w her symbol, its obvious she doesn't mean chosen in a good way.
also that girl who was guiding off around the gallery was dao too. its apparent from her voice. i think she takes on the form of her previous victims like she impersonates chai after that. her point here, was to make sure she didn't scare off her victims before they were guided to the cave, that's why she doesn't appear in her true form.
the show was about demons in the end. demons (and demonic ppl) punishing the innocent (pink and lada) while messing w evil humans (chai and off).