Just out of curiosity, have you ever thought of a Steven Universe Princess Tutu au? Like Ahiru could be the daughter of Tutu, and the gem is red helenite, which could look similar to the heart shard, or angel aura. Fakir could be an emerald, Mytho could be diamond or citrine, and his gem could be cracked/ partially shattered, thus giving him no personality until they find the pieces missing/find a way to fix his gem. Rue could be a tainted gem and could be red garnet or red jasper. Mytho could have turned against his ally before the gem war, the raven, aka jet/onyx when he found out that the Raven wanted to destroy humankind because he gained an affinity for humans and their strange ways and he and Tutu were allies in the gem war, but the Raven hit Mytho by surprise and cracked/shattered his gem partially so that he kept his body, but in a way, lost his mind. centuries later, Tutu fell in love with a younger Charron because he reminded her of a young Mytho when he took fakir under his wing so to speak and taught him about horses and fairy tales and such after finding Fakir wandering around one day after a trying day with Mytho. Then after Ahiru is born and Tutu fades/dies/disappers in a flash of light he becomes really distant from Ahiru because Tutu is gone and he doesn’t know how to help Mytho and later Rue comes in and though she’s on the Raven’s side at first, she later switches over to Mytho’s side because she want’s to help him.
It sounds like a cute idea, though, and I know my friends who are into it will love to see this. :) Thanks for sharing!