Another scenario could be Marinette fighting in a team-up with other Miraculous holders against a supervillain who has somehow managed to steal multiple Miraculouses. This would require a lot of coordination and strategy among the team, and Marinette would likely be at the forefront, leading the charge and coming up with plans to defeat the villain.
In some fanfictions, Marinette might fight against an alternate version of herself. This could be a version that has been corrupted or turned evil. It would be a really intense battle as she has to face someone with the same skills and knowledge as her. She'd have to dig deep and find the strength within herself to overcome this internal conflict.
A common opponent is Chloe when she gets akumatized. In fanfiction, their battles can be more intense and personal. Marinette, as Ladybug, has to deal with Chloe's over - the - top attacks and her mean - spirited nature while trying to purify the akuma.
One idea could be that Marinette vomits due to extreme stress. Maybe she's facing too many akuma attacks in a short time and the pressure gets to her physically. Another could be related to a strange side - effect of using the Ladybug Miraculous. For example, if she overuses her powers in a short period, it might cause some sort of physical reaction like vomiting.
One interesting plot could be Felix discovers Marinette's secret identity as Ladybug by accident. He then has to decide whether to use this information for his own gain or keep it a secret. Maybe he starts to develop feelings for her because of her dual identity and the strength she shows as Ladybug.
A common plotline is Marinette's hair being down as a sign of a transformation in her character. For example, she might let her hair down when she decides to be more assertive or when she's finally coming to terms with her feelings for Adrien. It shows a more vulnerable and yet confident side of her.
She could be turned into a mouse - like creature by an experimental akuma attack. As a mouse, she discovers new parts of Paris that are usually hidden from humans. This could include secret underground tunnels or the rooftops in a whole new perspective. She might also meet other kwamis who are more active in these hidden areas.
One common plotline is about Luka helping Marinette deal with her feelings for Adrien. He becomes her confidant and through that process, they start to develop deeper feelings for each other.
One interesting storyline could be Alya and Marinette teaming up to solve a mystery that is not directly related to the Akumas. For example, they might be trying to find out who is behind a series of strange disappearances in their neighborhood. They could use their unique skills - Marinette's creativity and Alya's investigative journalism skills - to piece together clues.
In this fanfiction, Ladybug could be ill and in bed. Chat Noir, being the caring partner he is, tries to take care of her. He brings her soup (even though he's not very good at cooking) and tries to cheer her up. Ladybug, on the other hand, is a bit frustrated at being sick but is also touched by Chat Noir's efforts. They end up having a deep conversation about their feelings for each other, but still keep it within the boundaries of their superhero partnership.
One scenario could be Marinette sacrificing herself to save Paris from a powerful akuma. She might use her Ladybug powers in a way that drains her life force but stops the villain. Another could be that she's poisoned by an enemy who targets her as Ladybug and slowly succumbs to the toxin, with Chat Noir desperately trying to find a cure.
One plot idea could be that Marinette and Felix are paired up for a school project. Felix, initially cold, starts to see Marinette's kindness and creativity, and they develop an unexpected friendship. This could lead to some comical moments as Marinette tries to hide her Ladybug identity from him while Felix is being his usual perceptive self.