In this fanfiction, a great plotline could be how Harry as Petunia deals with Snape. Given their past relationship in his original life, it would be very different now. Maybe Petunia!Harry could try to mend the broken relationship between Snape and Lily. He might also use his knowledge of Potions to help Snape in some way, while also trying to keep his true identity a secret from Snape who would be very suspicious of any sudden changes in Petunia.
One interesting plotline could be Harry, now as Petunia, trying to prevent the Dursleys from being so cruel to the real Harry. Since he has the knowledge of his past life, he might use it to subtly change the family's attitude. Another could be his interactions with the wizarding world in this new identity. He would have to hide his true self while still being involved in some way.
Well, a possible plotline is that as Petunia, Harry might discover new magical abilities or aspects of magic that were overlooked in his previous life. He could use this knowledge to his advantage, perhaps to protect his family from the dark forces that are yet to come. Also, there could be a lot of internal conflict as he adjusts to being in a female body and having a different role in the family and the wizarding world.
Perhaps he struggles with his new identity as an archangel while still having the memories of his past life as Harry Potter. He could have a hard time fitting into the angelic realm, yet also find new allies among the angels who are intrigued by his unique situation.
One interesting plotline could be Harry exploring the ancient Peverell heritage and discovering long - lost magic associated with the Peverells. Maybe he finds a hidden Peverell vault filled with powerful artifacts. Another could be his interactions with other descendants of the Peverells, which might lead to new alliances or rivalries.
Another plotline could involve the founders trying to fix the problems they see in Hogwarts today. Maybe they are not happy with how the houses are divided now and attempt to create a more unified system among the students.
One interesting plotline could be Minato using his ninja skills in the wizarding world. For example, his speed and stealth might help him in tasks like sneaking around Hogwarts undetected. He could also use his sealing jutsu in unique ways, perhaps to contain dark magic or protect secrets.
One interesting plotline could be the main character using their wishes to change some of the major events in the Harry Potter universe. For example, they might wish to prevent certain characters from dying. Another could be using a wish to gain a special power that helps them in their adventures at Hogwarts, like being able to communicate with magical creatures more easily.
One possible plotline could be the main character using their new identity as a Black to uncover long - hidden family secrets within the Black family tree. Maybe they find out about forgotten magic or alliances that can help them in their new life.
Another plotline could involve Petunia getting involved in one of the Marauders' adventures by accident. Maybe she stumbles upon them while they are exploring a secret part of Hogwarts and has to work with them to get out of a tricky situation.
One possible plotline could be that Petunia initially hates James but then gradually discovers his good side. Maybe through some accidental encounters where James shows his kindness and courage, Petunia starts to question her long - held prejudices against him.
One possible plotline could be that Petunia has a sudden realization of how unfairly she has treated Harry over the years and tries to make amends. She might start by secretly helping him with things around the house or protecting him from Dudley's bullying.
One interesting 'Harry Potter Petunia Dursley' fanfic could be one that explores Petunia's childhood and how her relationship with Lily might have affected her view of Harry. For example, a fanfic could show that deep down, Petunia was always a bit envious of Lily's magical abilities, but also loved her sister in a complicated way. This envy could have then translated into her cold treatment of Harry.