Sometimes, it's just a different take on their characters for the sake of creating drama. The author wants to explore a new dynamic that goes against the normal love - interest relationship. So they make Adrien and Marinette hate each other to see how the story unfolds in a completely different way from the original plot.
The plot could develop as they are forced to work together on a project. Despite their hatred, they start to see each other's good sides. For example, they might be paired for a school assignment. As they work on it, they realize that their initial hatred was unfounded.
One reason could be jealousy. Maybe Hermione is jealous of Harry's fame and Harry is jealous of Hermione's intelligence. Another reason might be conflicting views on how to deal with Voldemort. Hermione might advocate for a more academic, research - based approach while Harry just wants to go and fight.
One possible reason could be that Marinette has been acting strangely in ways that seem to Adrien to be related to Hawkmoth. Maybe she has been seen in places or at times that are suspicious, like near akuma attacks or where Hawkmoth might be operating from. Another reason could be that someone has been spreading false rumors about Marinette, leading Adrien to believe she has some connection to Hawkmoth.
One possible motive could be that in the fanfiction, Adrien is being controlled by some dark magic or an evil force. This external influence makes him act against his true nature and kidnap Marinette. For example, perhaps a villain has cast a spell on him to use him as a tool to get to Marinette, who might have some special power or knowledge that the villain desires.
There are fanfictions where Marinette and Adrien go on a magical adventure outside of Paris. For example, they could be transported to a parallel dimension full of strange creatures. In these stories, their relationship often deepens as they face these new and exciting challenges together. Some fanfictions also delve into their family histories and how that affects their relationship as Marinette and Adrien.
One more to consider is 'Kiss in the Moonlight'. This fanfic sets the kiss in a very romantic and dreamy setting, perhaps under the light of the moon during a special event in Paris. It explores how this kiss could be a turning point in their relationship and how it might impact their future interactions in the Miraculous world.
One popular 'Adrien likes Marinette' fanfiction is 'The Hidden Feelings'. It beautifully explores Adrien's growing affection for Marinette in a school setting. Another great one could be 'Adrien's Discovery', where he gradually realizes his true feelings for her through various encounters. There's also 'Marinette in Adrien's Heart' which focuses on how his feelings for her start to change his perspective on their relationship.
They might hate each other because of differences in their personalities. Austin could be more outgoing and impulsive while Ally is shy and methodical. These differences might lead to clashes. For instance, Austin might make decisions on the fly that Ally doesn't agree with, causing friction. Also, jealousy could play a part. If one of them gets more attention or success than the other, it could breed envy and hatred.
One possible plot could be Marinette struggling to raise the baby on her own while dealing with the heartbreak of Adrien leaving. She might find support from her friends like Alya, who helps her through the tough times. Meanwhile, Adrien could be off on some self - discovery journey and later realizes his mistake.
There could be a lot of internal conflict. Marinette might be used to her shy yet determined self, and Adrien his more reserved but princely nature, and Luka his laid - back attitude. When merged, they'd have to reconcile these differences within the new entity. This could lead to a very character - driven story as they learn to function as one.