The plot I have in mind is fairly straightforward. Your character is a member of an ancient, superstitious society ruled by powerful priesthoods dedicated to old, strange gods. She might be a priestess herself, a noblewoman, a princess or a peasant girl. Whichever, one grim night the priests of the God Below come to her home. Stars and dreams have revealed to them that she is to be the next consort of the avatar of the God Below. She's taken from her home to the priests' temple-city, ritually prepared, and on the auspicious night she is offered at the doors of the avatar's fane in the ancient heart of the city. The doors open for her, and she's commanded to enter. They close behind her, and none outside know what happens after.
Our game is about what comes after, as the god of the ancient city takes her as his lover and priestess. What that ultimately means can vary, but this plot was inspired by the following image:
I'm looking for literate, interested female writers to take the consort's role in this story. I think we can work out something entertaining together. Please send a PM if this plot interests you.