One idea could be to start with Chat Noir being in love with Marinette first. He might be more forward in his pursuit, which could throw Marinette off at first as she's used to being the one with the secret crush. For example, he could leave her little gifts as Chat Noir, which would make her both flattered and a bit confused.
One idea could be exploring a time - reversed scenario in the love square. For example, Ladybug and Chat Noir already know each other's identities and are in a relationship, but then something goes wrong that makes them lose their memories of each other and they have to start from scratch as superheroes. Another plot could involve a villain who targets the love square specifically, trying to use their feelings for each other to create chaos. Maybe the villain can manipulate their emotions so that Ladybug starts to dislike Chat Noir and vice versa, and they have to fight against this emotional turmoil while still saving Paris.
One interesting plot could be an alternate universe where the Miraculous holders have different powers. For example, Ladybug might have the power of ice instead of her usual abilities. Another could be a story where the villains and heroes have to team up to face a greater threat. This would change the whole dynamic between them.
Adrien, in a reverse love square, could become more empathetic towards Marinette's feelings. He might notice things about her that he didn't before, like how she gets nervous around him. This could make him a more understanding friend and potentially a better partner later on. He would also have to deal with his own insecurities about whether Marinette likes him for who he really is or just because he's a famous model.
One idea could be a story where the Peacock Miraculous has a unique malfunction that causes it to create unexpected akumas. For example, instead of creating the usual villains, it creates akumas that have the power to spread positive emotions but in a chaotic way that still disrupts Paris. Another idea is a fanfiction where the holder of the Peacock Miraculous has to team up with Ladybug and Chat Noir to fight against an ancient evil that is specifically drawn to the power of the Peacock. This could involve exploring the history of the Miraculous and its connection to this new threat.
Well, you could have a fanfiction where the umbrella is a key element in a time - traveling adventure. For example, Ladybug and Chat Noir find an old umbrella that transports them to a different era in Paris' history. Or perhaps an akumatized villain uses umbrellas to spread his or her power, and Ladybug and Chat Noir have to find a way to counter this by using the unique properties of Ladybug's own umbrella. Also, it could be that the umbrella is a portal to another dimension, leading to a whole new set of challenges and adventures for our heroes.
Well, you could write a fanfiction where Edendaphne has to team up with a new character. They could have different personalities and powers, which would lead to some interesting conflicts and resolutions. For example, if the new character is really impulsive and Edendaphne is more cautious. Also, you could show how Edendaphne deals with the challenges of keeping her identity a secret, just like Ladybug and Cat Noir do.
You could write a fanfiction where there are new Miraculous holders. Imagine a character who discovers a long - lost Miraculous and has to learn how to use it. This new character could team up with Ladybug and Chat Noir, or they could start out as an antagonist because they misuse the power at first. Their journey of learning to be a true hero or villain could be really engaging.
A cool concept for Miraculous Ladybug fusion fanfiction could be a time - travel related fusion. Imagine Ladybug fusing with a past version of herself. This would bring about a character with double the experience and different perspectives on how to use the Miraculous. They might be able to come up with new strategies to defeat Hawkmoth that neither the present nor the past Ladybug could have thought of alone.
One idea could be that Marinette gets isekaied into a magical realm where the Miraculous have different powers and she has to learn to adapt quickly. Another could be that Adrien is sent to a parallel world through an isekai event and he meets alternate versions of his friends and enemies.
One idea could be a dance competition in Paris where Marinette and Adrien are secretly the superheroes. They use their super - agility and grace in the dance, which surprises everyone. Their opponents think they are just normal kids but they show extraordinary skills. Maybe there could be a villain who tries to disrupt the competition by using some dark magic related to the dance floor.