Swapping diamonds for pearls
Maribat, Merfolk AU, Felinette, Fantasy AU, Marinette gets adopted by the Batfam, No Miraculous AU:
The setting is a town on the coast. To ensure the goodwill of the sea gods, the town sacrifices one of their young people to the sea, when the signs show it's time for a sacrifice. It's been a few decades since the last sacrifice when Marinette suddenly feels inexplicably drawn to the ocean. She wakes up at night hearing songs and finds herself at the shore without memory how she got there several times.
One of the things she can't remember, because humans forget their encounters with merfolk, is how she helped a young mer protect a baby seal.
That young mer is Damian, who took a liking to the girl who protected the pup of his favourite seal. So he decided to claim her as part of his pod, not knowing that it starts a transformation process.
Marinette was engaged to Adrien, but she more and more feels that this is wrong and when her behaviour is noticed, the priestess declares it's a sign that it's time for a sacrifice and Marinette has been chosen as the sacrifice. At that point she breaks off the engagement. She gives Adrien the diamond ring back and wears jewellery with pearls which declares her as the sacrifice.
Felix, Adrien's cousin and the young lord of the town starts researching in his library. Secretly he's in love with Marinette, but he also loves his cousin and since Marinette is one of the few people Adrien could be himself around, he didn't interfere, but encouraged Adrien to propose. He tries to find anything to reverse the signs, but he also doesn't wish to evoke the sea gods' wrath. He has to think about his subjects. If they can't fish as much anymore, it would be devastating for the town.
He finds out, that the sacrifices turn into merfolk and the only way to stop this is, to convince the mer who claimed a human to give up their claim. But Felix is too late and Marinette has already been sacrificed.
At sea she is soon found by Tim, who claimed the last sacrifice, Cass. He was once a sacrifice himself and figures out what happened (mainly) and brings her to the pod. Damian confesses he claimed her, not knowing it would transform her. He did it, because he thought it would protect her. Bruce explains, that they usually claim humans who don't have anything keeping them on land. Often orphans or, like in Tim's case, children who are neglected or abused by their parents. But a pod can only claim a human every 15 to 25 years, because the successful transformation takes energy from the whole pod.
Marinette had connections on land and she has a hard time giving up on them. But it's not reversible and she likes her pod and befriends mers from other pods.
One day she finds Felix in a boat suspiciously close to the small island the pod lives around and hears him yelling for her. The pod is a bit annoyed, because although they keep sharks away and help with fishing, sink pirate ships and bring survivors of sinking ships to the shore, invading their home is something they really don't like.
Marinette shows herself, to convince him to leave, but because he forgets the encounter, he's back the next day. This time Marinette drags his boat to a hidden beach and writes in the sand to only meet her here, so even if he would forget their encounters, he could still read the message. They figure out a system. He takes something to write with him, so he can write down, what happend and he can read it again after he forgets what they talked about.
During these meetings they get closer and finally Marinette falls in love with Felix. At first Felix felt conflicted and wanted to tell Adrien, but Adrien didn't want to hear anything about Marinette and after Felix found Adrien and one of his warriors, Kagami, at a tryst, he decided, that it would be better this way.
After they kiss, they find out that now Felix can remember their talks.
Felix starts to wonder if they can have a future when his mother urges him to find a bride, someone to share the burden of reigning over the town with. But either he has to cheat on the woman he loves and his wife or he has to end things with Marinette or he has to defy his mother and sooner or later the court or even his king for the rest of his life. So, he starts to research again, but he only finds out, that the transformation can only be stopped and reversed as long as the person isn't really part of a pod.
Marinette knows it's irreversible. The only option she can see is, if he wasn't lord anymore, but she thinks she can't ask that of him, so she looks into potions to make him forget her entirely.
This is what she's busy with, while her friends band together and find Felix waiting for Marinette at the beach. Felix decided on his own to give the title to Adrien and step down, so he wouldn't have to leave Marinette. He wanted to tell her but only finds mers he only knows of from Marinette's stories. They offer him that one of them could claim him, since Marinette's pod can't do so, but it's not the only pod out there. True, the other pods have their own territories, but they are close enough to befriend each other. They only ask him to be sure this is what he wants. It is.
So, in the end they can still have a happy ever after 😊
