One possible plot could be that Petunia discovers she has a long - lost relative who was a wizard and that relative had some sort of baby - related magic that is now connected to Harry. So, Petunia has to step in and protect Harry from dark forces that want to use this magic for evil. Along the way, she starts to see Harry as more than just the unwanted nephew and forms a real bond with him.
In a more complex plot, Petunia could be cursed by a dark wizard. The curse is related to babies and it starts to affect Harry as well because of their blood connection. To break the curse, they have to figure out the mystery behind an ancient baby - centric magic spell. This would lead them to explore hidden parts of the wizarding world. As they do this, Petunia realizes how much she has wronged Harry in the past and tries to make amends. They face many challenges together, all centered around this baby - related magic, and in the end, their relationship is completely changed.
Yes, there might be some out there. Fanfic writers often come up with unique and sometimes wild ideas. They might explore the idea of Petunia having some sort of connection to Harry in a way that involves babies, perhaps in an alternate universe or a what - if scenario. It could be about Petunia having a change of heart and taking in Harry in a more motherly way that could be related to the idea of new - borns or babies in a metaphorical sense.
In a more comical plot, the lemon could be a mischievous magical object that keeps causing chaos in Petunia's house. It might make things float or turn into strange creatures. Petunia, being the uptight person she is, has to deal with this lemon - induced mayhem while also trying to keep up appearances in front of the neighbors. This could lead to some really funny situations and a change in her attitude towards the strange and magical over time.
One possible fanfic could be about Petunia Dursley finding a magical toy that once belonged to Harry Potter's parents. Maybe she discovers it in the attic and it starts to show her memories of Lily and James Potter. She realizes that she has been wrong about Harry all along and decides to change her attitude towards him.
One possible plot could be that Petunia is somehow magically enslaved by a dark wizard. Harry, upon finding out, feels a sense of obligation to save her. He might have to use his knowledge of magic and his connections at Hogwarts to figure out a way to break the spell. Along the way, he could discover some secrets about Petunia's past that were related to the wizarding world.
The plot could start with Petunia having a strange encounter with an angel. The angel seems to know things about her past and her relationship with Lily. At the same time, an elf, which has been observing Petunia for some reason, decides to approach her. The angel wants to help Petunia understand the importance of magic and her family's place in it. The elf provides some practical help, like getting access to some magical items. As the story progresses, Petunia changes her view of the wizarding world, and together with the angel and the elf, they might even influence some of the events in the wizarding world, like helping to protect Hogwarts or something similar.
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.
In a non - offensive and family - friendly fanfic idea, perhaps Petunia Dursley discovers a magical cock cage (not in a vulgar way) that has some connection to the wizarding world. Maybe it was left by a wizard who visited Privet Drive by mistake. Petunia, being the nosy character she is, tries to figure out what it is and how it works. This could lead to a series of comical events as she fumbles with this strange magical object, all while still maintaining her strict, Muggle - like personality.
A fanfic could connect them by having a toy that was passed down from Lily Potter to Harry, but Petunia has kept it hidden all these years. When Harry discovers it, it causes a big conflict as Petunia doesn't want to let go of the last piece of her sister she has in that way. But eventually, it could lead to a moment of reconciliation between them.
The plot could involve Petunia using her witch powers to protect Harry from the Dursleys' abuse. She realizes that she has a responsibility towards her sister's son and uses her magic to create a safe haven for him within the Dursley household. This would be a big change from her original character who was so against magic.
One good Petunia - related fanfiction could be 'Petunia's Secret'. It delves into Petunia's hidden emotions and her complex relationship with the wizarding world. In this fanfic, it might show how she really felt about Lily's magical abilities all along and her internal struggle with envy and love for her sister.