One great fanfiction is 'The Butterfly's Reign'. In this alternate universe, Hawkmoth has successfully won, and Ladybug and Chat Noir have to find a new way to fight back from the shadows. It's full of mystery and intrigue.
The main reason is the chance to explore different scenarios. Fans can see what would happen if the characters had different personalities or if the power dynamics changed. For example, in some alternate universes, Marinette might be more assertive as Ladybug from the start.
In an alternate universe where the Miraculous holders are more like superheroes in a traditional sense, Felix and Marinette could start as rivals. They both want to be the top hero in the city. But as they face bigger threats together, they realize they are stronger as a team. This mutual respect could turn into love over time as they see each other's true selves.
This event in the fanfic could also lead to new characters emerging. Maybe someone would try to take on Ladybug's mantle in a different way. Or new villains could rise, seeing the opportunity in the chaos. The magic of the Miraculous might be affected too. Since Ladybug was an important part of the magical balance, her death could have unforeseen consequences on the powers and the Miraculous themselves.
One idea could be a crossover where Ladybug and Cat Noir end up in the world of Steven Universe. They could team up with Steven and the Crystal Gems to fight a common enemy that has the power to disrupt both their universes.
Befana can be a magical helper. In fanfiction, she often uses her powers of flight and gift - giving to assist Ladybug and Chat Noir. For example, she might give them a magical item to defeat a particularly tough akuma.
Ladybug and Chat Noir are still very popular, even in alternate universes. Their dynamic is so iconic that writers like to explore different versions of it. Marinette and Adrien are also popular as they are the alter - egos. But other characters like Luka and Kagami are also getting more attention in alternate universe fanfictions. Luka, for example, might be given a more prominent role as a Miraculous holder or a key figure in a different plotline.
Well, in some Miraculous Ladybug Alternet Universe Fanfiction, there are concepts like the Miraculous having different origins. Instead of being created by the Kwamis' magic in the traditional way, they could be the result of a scientific experiment gone wrong. This would change the nature of how the heroes interact with their powers. And then there's the idea of a 'dark' Ladybug or Chat Noir. Maybe they've been corrupted in some way and are now fighting against the good guys, which would be a really cool and edgy take on the story.