Maybe the Princess Fragrance gets into the wrong hands and is used to create a false utopia where everyone is blindly following the commands of the holder. Ladybug and Chat Noir must break this spell by finding the source of the fragrance's power.
One plot idea could be that Princess Justice discovers a new Miraculous that has been hidden for centuries. This new Miraculous could have unique powers that she has to learn to control while also facing off against a new villain who is after the power of this Miraculous.
One plot idea could be Marinette having to deal with the pressures of being a princess while also being Ladybug. For example, she might have to attend royal balls and diplomatic events in her princess role, all while secretly protecting Paris as Ladybug. Another idea is that an evil villain targets her specifically because of her dual identity, trying to take over both the kingdom and Paris. Maybe there could also be a plot where she has to choose between her duties as a princess and her responsibilities as Ladybug, creating an internal conflict.
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 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.
One idea could be that Ladybug and Chat Noir are sent to space on a mission to stop an alien villain who is stealing energy from planets. They have to adapt to zero - gravity combat and use their powers in new ways. For example, Ladybug's yo - yo could be used to grapple onto spaceships.