Sun and Moon AU

The Sun and Moon AU was created by Lumina Xandra. It's basically the story of Luna and Celestia from MLP. Mabel is the Sun Goddess, Dipper the Moon God and they are both rulers of the Kingdom of Gravity Falls. All the other characters also have powers relating to and/or are the personifications of, the earth, nature etc etc. but only Mabel and Dipper are royalty. It goes the same as the original story, with Dipper growing resentful and going rogue and Mabel having to banish him. Sadly there hardly any fanfics. But this au is amazing and the creator has some wonderful art and animatics.