I've a very vague idea with me right now.
The heavens rely on human worshipers to be tangible. Without humans, they cannot thrive, they cannot exist, they are not.
So religions and gods have come and vanished, with humans none the smarter about what has been happening.
Except somehow, one goddess has become truly tangible. She has gone from being a creation of thoughts to a creation of solid flesh, perhaps because she rules over the pleasures of the flesh.
Her worshipers have been dwindling, and she is on the verge of becoming nothing. Indeed, she is powerless, little stronger than a normal human. Now, fallen, she must seek help, but is there anyone willing to help someone that they do not believe in?