One idea could be a fanfic where Petunia discovers a hidden letter from Lily that reveals more about their family history and the magic in their bloodline. This could lead to her having a change of heart towards Harry and the wizarding world.
There could be a fanfic where Petunia meets some of the minor wizarding characters, like the Weasley twins in disguise. And through this encounter, she starts to understand the wizarding world a bit better and realizes that not all magic is as bad as she thought. This could be a humorous and family - friendly take on the 'Harry Potter' universe.
One idea could be a fanfic where Luna teaches Harry about some of the more unusual magical plants and their uses. It could be a story of discovery and learning. Another could be a fanfic set during the holidays where Luna invites Harry to her home and he experiences the unique lifestyle of the Lovegood family. And perhaps a fanfic where Luna and Harry work together to organize a school event that promotes acceptance of all kinds of magic and magical beings.
Another idea is to write a fanfic about the magical creatures of the 'Harry Potter' world from their perspective. Maybe a story about how a hippogriff views the wizarding students who come to visit it, or how a house - elf dreams of a different kind of life while still serving their wizard family.
Another interesting idea is a fanfic where a group of students start a club dedicated to the study of snakes in Hogwarts. They go on quests to find rare snake species in different parts of the wizarding world and learn about their unique magical abilities. Along the way, they face challenges and make new friends, all while respecting the snakes and the magic associated with them.
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.
One idea could be a fanfic where Fleur and Gabrielle are helping to teach younger students at Beauxbatons about the different magical cultures. They could share stories about their own experiences in the wizarding world and how different cultures interact. This would be a great way to explore their characters in a positive and educational way.
I don't think it's a very common type. Most 'Harry Potter' fanfics tend to focus on the magical adventures, the relationships between the main characters like Harry, Ron and Hermione, or exploring different magical elements in the wizarding world. While there are some that might delve into darker themes, the idea of Petunia abusing Harry isn't as mainstream as other topics in the fanfic community.
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.
A story about Harry Potter's first Christmas at Hogwarts. It could be about how he experiences the magic of the holiday in the wizarding world, with the floating candles, delicious feasts, and special presents. It would be a heartwarming story full of the joy of the season.
One great idea could be stories that explore the further adventures of the characters after the end of the series. For example, how Harry, Hermione, and Ron continue to protect the wizarding world from new threats. It could also involve the next generation learning magic at Hogwarts and facing their own challenges in a way that stays true to the original values of the series.
Aunt Petunia could discover a lemon tree in her garden that has magical properties. Since she's always been envious of the magical world (even if she doesn't admit it), she might try to use the lemons from the tree to gain some sort of power or advantage. For example, she could think that if she eats the lemons, she'll become more beautiful like the witches she's seen in Harry's pictures.