Well, a plot could be that there is a magical artifact that binds the love square together even more. But this artifact also has a dark side. When they are near it, their emotions become amplified. So Ladybug becomes overly possessive of Chat Noir and Chat Noir becomes extremely overprotective of Ladybug. This causes problems in their superhero duties as they can't focus properly. Meanwhile, their civilian selves, Marinette and Adrien, also start to feel these extreme emotions in their daily lives and it creates chaos in their relationships with their friends and family.
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 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 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.
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.
One idea could be that a villain creates a love potion and accidentally makes Chat Noir fall in love with the wrong person, like a civilian. This would cause chaos as Chat Noir tries to court this person while also keeping his identity a secret. Another plot could be Ladybug getting affected by the love potion and falling for Hawk Moth, which would put Paris in great danger as she might be tricked into giving up her Miraculous. Or perhaps a love potion gets spilled in the school and all the students start acting strangely in love, and Ladybug and Chat Noir have to find a way to reverse it without revealing their identities.
One idea could be Multimouse having to team up with an unexpected ally, like a villain who has a change of heart for a short time. Another could be Multimouse getting lost in an alternate dimension and having to find her way back while facing new challenges.
One idea could be Ladybug and Chat Noir having a heart - to - heart conversation in bed after a particularly tough battle. They could share their fears and insecurities that they usually hide behind their superhero personas.
One idea could be a story where the child of Ladybug and Chat Noir discovers their parents' secret identities by accident. Maybe they find a hidden Miraculous box in the attic and start to figure out what it means.
For a Miraculous Ladybug class fanfiction, a plot about a cursed object in the classroom could be interesting. The object spreads negative energy, causing the students to fight and argue more. Ladybug and Chat Noir suspect that it's an akuma - related thing, but they can't find the akuma. As they investigate, they discover that it's actually an ancient cursed item that was accidentally brought into the class. They have to find a way to break the curse without revealing their identities, and also deal with the fact that their classmates' relationships are falling apart because of the curse.
Maybe there's a werewolf akuma. Hawkmoth takes advantage of an already existing werewolf in the city and akumatizes it. This werewolf - akuma has enhanced powers and is causing chaos. Ladybug and Chat Noir must figure out how to defeat it. They might need to discover the true identity of the werewolf to break the akuma's hold. It could be a person who was bitten recently and is struggling to control their new form.
Another plot could be that a crime wave hits Paris, and all the evidence points to Chat Noir as the perpetrator. Ladybug is torn between believing in her partner and the mounting evidence against him. She has to dig deeper into the case to find the real criminal who is framing Chat Noir and clear his name.