One possible plot could be that Cat Noir has made a mess while testing out some new gadgets in his lair. So he has to clean it all up before Ladybug comes over. He might struggle with getting his cat - like self to be organized, like constantly being distracted by shiny objects while cleaning.
The plot could involve Cat Noir's realization that his messy lair is affecting his superhero efficiency. So he decides to clean house. As he cleans, he could find some old mementos from past battles or encounters with Ladybug, which makes him reminisce. And in the process, he might accidentally trigger one of his old gadgets and create more chaos before finally getting everything in order.
I haven't read a particular 'cat noir cleaning house fanfic' myself. However, you could check out some Miraculous Ladybug fan communities. Fans often share their fanfics in those groups, and you might be lucky enough to find one where Cat Noir is cleaning his house. It could be interesting to see how the author portrays his character in such a domestic situation.
One possible plot could be that Naruto is somehow transported to the world of Ladybug and Cat Noir. He might initially be confused but quickly adapt his ninja skills to the new environment. He could team up with Ladybug and Cat Noir to fight against a common enemy, perhaps an akuma that has powers similar to some of the foes in the Naruto universe. Naruto's chakra and jutsu would add a new dimension to their battles.
In the fanfiction, the plot could start with Cat Noir proposing to Ladybug in a really romantic and unexpected way. Then they would start planning the wedding. Ladybug might be a bit hesitant at first because she's worried about how it will affect their superhero duties. But as they work through it, they find ways to balance their personal and superhero lives. And at the end, they have a magical wedding ceremony filled with love and hope for the future.
One possible plot could be that Hawkmoth manages to finally corrupt Cat Noir. He might start causing chaos in Paris, attacking Ladybug instead of helping her. Ladybug would then be in a difficult situation, having to either try to save her partner or defeat him to protect the city.
One idea could be a time - travel plot. For example, Ladybug and Cat Noir are sent back in time to when the Miraculouses were first created. They have to figure out how to get back to their own time while also protecting the secrets of the Miraculouses in the past. Another idea is a role - reversal. Maybe Ladybug loses her powers for a short time and Cat Noir has to step up even more and take on some of her traditional responsibilities. He could struggle with the different approach needed for leadership.
In such a fanfiction, Ladybug might discover a hidden akuma while cleaning the house. She could then have to quickly transform and fight off the akuma without making too much of a mess in the process.
A good 'Cat Noir and Ladybug Fanfic' often has interesting character development. For example, seeing how Ladybug becomes more confident in her leadership role or how Cat Noir matures in his feelings for Ladybug. It makes the characters more relatable.
The power struggle is also a theme. Gabriel as Hawkmoth has power, and Cat Noir has his own powers. Fanfics might explore how they use or misuse their powers in relation to each other. For example, when they face off in battles, the power dynamics are constantly shifting.
One plot could be that the cat avengers are split into two groups due to a misunderstanding. One group believes that the other is working with a group of rats who are stealing cat food. As they fight among themselves, the real villains, a gang of raccoons, start to take over the town. Eventually, the cats realize their mistake and reunite. They then use their combined powers, like the flying cat to scout the raccoons' movements, the strong cat to fight them directly, and the invisible cat to launch surprise attacks, to drive the raccoons out of the town.
Well, perhaps Chat Noir got seriously injured during a fight with a powerful akumatized villain. His partner Ladybug might be worried sick as she rushes him to the hospital. Maybe his identity is at risk of being revealed there too.