Eros
The Greek deity lost his powers over time, very few still know him in the middle ages.
Odly enough, because he was the god of wine and pleasures of the flesh.
Wonderbra gave him a new hope by giving him back his popularity back; he can finaly have new mortals to manipulate,
like any god does.
He wants the demons out of the way, simply because they threaten the last of his worshippers.
He helped once to vanquish them and is ready to give a hand to do it again.