I have a question about your OC, Joan. Judging by how Ratau and Ratoo were part of her cult I assume she was the previous bearer of the Red Crown, with Ratau being the next vessel after her. So how did Joan’s reign end? What was her downfall seeing that she’s more of a villain?
One was her own ambition. Joan's goal was to eradicate the Old Faith's devotion from the lands, making the bishops vulnerable and easy to kill. In other words, a big crusade.
She created an army of crusaders to take over the Old Faith's temples. She did it with Leshy's, but she couldn't finish her quest. Shamura frustated all her plans by turning more than the half of her army against her... and killed in the process.
Although Joan came back to life and TOWW had commanded her to retire and protect his temple, she finally refused and pulled the Red Crown out of her head.
At that moment she realized why she wouldn't taste victory anyways, the second reason of her downfall: the prophecy. She always thought of it as a false hope, a tool from the bishops even. The only "truth" she believed was that she was chosen by a god and nothing could stop her.
She went alone to fight Shamura for revenge. She knew she wouldn't make it, but she would die the way she wanted to.