One possible plot line could be Aunt Petunia having a change of heart towards Harry due to some magical event in the fanfiction. Maybe she discovers a hidden side of magic that makes her see Harry in a new light.
In some fanfictions, there might be a plot where Aunt Petunia is forced to protect Harry from a new dark threat in the wizarding world. This could lead to some really interesting interactions between her and the magical elements she has always despised. For example, she might have to use some basic magic spells she learned from Harry in a moment of desperation, which would completely change their relationship dynamic.
Perhaps Aunt Petunia is a witch who was cursed long ago. The curse made her forget her magic and act like a Muggle. When Harry unknowingly breaks the curse, she suddenly has her powers back. She then has to face the wizarding world again and deal with all the changes that have occurred since she last remembered her true self. She might even have some unique powers that are different from the norm because of the curse.
There are fanfictions where Aunt Petunia has a change of heart towards Harry much earlier in the story. Instead of treating him badly, she starts to secretly teach him some basic things about the wizarding world that she learned from her sister Lily before she passed away. This could add a whole new dynamic to Harry's early years at the Dursleys.
One interesting 'Harry Potter Aunt Petunia' fanfic could be the ones that explore her relationship with Lily before she passed away. It might show how they grew up together and how their bond changed over time. Maybe there are fanfics where Aunt Petunia has to face her own insecurities regarding magic and her sister's special abilities.
There could also be other characters from the original Harry Potter series popping up. For instance, Dudley might be in there, and his relationship with both Harry and Aunt Petunia could be explored further in the context of this fanfiction. And of course, depending on the direction of the story, some of Harry's friends from Hogwarts like Ron or Hermione could make an appearance, especially if the story involves the wizarding world interfering with Aunt Petunia's life.
One interesting 'Harry and Aunt Petunia' fanfiction could be about Aunt Petunia having a change of heart and secretly protecting Harry from other threats in the wizarding world. Maybe she starts to understand the importance of magic and realizes she can't let her sister's son be in constant danger.
One possible fanfiction could be about Aunt Petunia having a strange encounter with a lemon - themed magical object. Maybe she accidentally uses it in a spell (in a non - canon, fan - created way) that makes her see a different side of the wizarding world she has always despised. This could lead to her having a change of heart about Harry Potter and his world.
Well, it could be quite strange. Maybe she's secretly a bit more interested in the wizarding world than she lets on. It might be a way for her to explore the stories from a different perspective, one that's not as judgmental as her usual self towards magic.
One idea could be that Aunt Marge accidentally eats a lemon - flavored magical treat that makes her temporarily nice to Harry. For example, she might start complimenting his schoolwork at Hogwarts instead of her usual mean - spirited remarks.
A possible plot could be a time - travel scenario where Harry and Petunia are sent back in time. They have to rely on each other to survive in the past, and in the process, they learn more about their family history and each other. This shared adventure could lead to a deeper understanding and a different kind of relationship between them.
She is very much concerned with appearances and normalcy. In the Dursley household, everything has to be in a certain order and conform to what she deems as a proper, non - magical lifestyle. This is part of the reason she is so resentful of Harry and his magical abilities.