I'd start with the main character finding an old relic that's to her deceased grandparents (or parents, idc) house and when she goes to said house, she finds out that she's the ruler (i don't care what platform you're on, but i like my idea, but that's bias, so tell me what you think)
Its pretty good but mines about kinda restarting supernatural but with a new character but insted of being where dean goes and gets sam its my characters pov castiel is going to be in it theres aback story to how my character meets castiel