Maybe it would be about Aunt Marge realizing Harry's good qualities. For example, she could see how brave he is in the face of danger. This newfound respect could lead to her liking Harry.
There could be a 'Aunt Marge likes Harry fanfic'. Fanfic communities are full of diverse interpretations of characters and relationships. It might explore a different side of Aunt Marge's character, perhaps in an alternate universe where she doesn't hold her usual grudges against Harry. You could also try reaching out to Harry Potter fanfic communities on social media platforms to ask if anyone has read or written such a fanfic.
It could develop into a more tolerable one. Harry might start to see Aunt Marge as a pitiful figure rather than just a mean old woman. Maybe he discovers some things about her past that make him more empathetic.
One possible plot could be that Aunt Marge, surprisingly, has a change of heart. She starts to see Harry's potential and decides to take him in. She might try to 'muggle - ize' Harry, making him fit into her more ordinary world. This could lead to many comical situations as Harry tries to adapt to her rules while still having his wizarding side peek through now and then.
Harry's life would be very different. He would no longer be under the Dursleys' roof. Aunt Marge might have different rules. He might have more freedom in some ways, like being able to explore the town more. But he would also have to deal with Aunt Marge's unique personality. He might have a more stable home life, though, with regular meals and a proper bed.
Maybe Harry finally stands up to Aunt Marge in a more assertive way this time. He could use his magic subtly to teach her a lesson without getting into too much trouble.
Aunt Marge could be developed by showing her having a moment of self - reflection. She might realize that her harsh treatment of Harry was wrong and start to be more empathetic. For example, she could see Harry's kindness towards animals and that could change her view of him.
The theme of secrets is also quite common. Aunt Marge may have some secrets from her past that are revealed in fanfics. This could be something related to her family history or an event that shaped her into the person she is. And of course, the theme of comedy is prevalent as her over - the - top reactions and behavior can be a great source for humorous stories.
In fanfiction, if Aunt Marge found out Harry was a wizard, she might have an extreme reaction. She could be terrified and try to distance herself from him immediately. Maybe she would even call the authorities in the Muggle world, not understanding that they can't do anything about wizardry.
In the fanfiction, they could be forced to work together on a project related to lemons. Maybe there's a local fair that requires everyone to contribute something lemon - themed. Through this shared task, they begin to understand each other better. Harry realizes that Aunt Marge has her own insecurities and Aunt Marge sees that Harry is not the troublemaker she thought he was. For instance, Harry could show his creativity and intelligence during the project, impressing Aunt Marge.
One interesting storyline could be Aunt Marge learning about the wizarding world and having her views completely changed. Maybe she accidentally stumbles upon Diagon Alley and is amazed by all the magic there. At first she's scared and wants to run away, but then she becomes curious and starts to interact with the magical beings, which in turn changes her perception of Harry and his world.