Maybe Marinette goes to a summer art camp and Adrien is also there. They work on a big art project together and their feelings for each other grow as they share their creativity and passion for art. During the summer nights, they stargaze and have deep conversations.
Another plot could be that there is a summer festival in Paris. Ladybug and Chat Noir have to protect the city during the festival. But in the midst of the chaos and fun, they find some quiet moments together. Ladybug starts to see Chat Noir in a different light, and they begin to develop a deeper connection than just being superhero partners.
One plot idea could be that Ladybug and Chat Noir have a huge fight due to a misunderstanding, which leads to a 'hate' phase. But as they face a powerful villain alone, they realize they need each other and slowly start to rekindle their friendship and the underlying love. For example, Chat Noir could be wrongly accused by Ladybug of working with a new villain. As they work separately to defeat the villain, they see the struggles each other faces and remember why they were partners in the first place.
One idea could be an OC who has a unique Miraculous that is related to a different aspect of nature, like a firefly Miraculous. The OC could struggle with controlling its powers at first. Another idea is an OC who is from a different country and brings in new cultural elements to the Miraculous world. For example, they might have a special fighting style based on their native martial arts.
One idea could be a crossover with the DC universe. Ladybug and Cat Noir could team up with Superman to stop an akumatized Lex Luthor who has somehow gotten his hands on a Miraculous. Another plot could involve a crossover with the Harry Potter world. Maybe Hawk Moth tries to steal magic from Hogwarts, and Ladybug and Cat Noir have to work with Harry and his friends to stop him.
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 exploring how Marinette balances her superhero duties with her pregnancy. Maybe she has to be more cautious during battles, and her partner Chat Noir has to be extra protective. Another plot could involve her friends and family finding out. Some might be overjoyed while others could be worried about how she'll handle it all.
One idea could be that the cats in the Miraculous Ladybug world are somehow affected by a new curse that makes them lose their agility. This would cause problems for Cat Noir as he tries to fight villains. Another could be a curse that makes all the cat - related items in Paris turn into something else, like the catacombs becoming a maze of thorns, and Ladybug and Cat Noir have to find a way to reverse it.
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.