Well, you could write a fanfiction where the dementors from Harry Potter are somehow related to the Abyss in Pandora Hearts. Maybe the Abyss has a connection to the world of the dead that the dementors come from. And then there could be a character from Pandora Hearts who has an ability to control or at least influence the dementors. This could lead to a really interesting story about power, redemption, and the nature of good and evil in both universes.
One idea could be a crossover where characters from both universes meet in a magical realm. For example, Harry Potter characters could find themselves in the world of Pandora Hearts and have to deal with the strange creatures and the complex power dynamics there. Another idea is a story where the magic systems of both worlds combine in unexpected ways. Maybe a Hogwarts student discovers a Pandora Hearts - style power within themselves.
An interesting Pandora Hearts OC fanfiction idea could be an OC that is a hybrid of a human and a Chain. This OC could struggle with their identity, being neither fully human nor fully a Chain. They could be on a journey to find out where they truly belong. Also, an OC that is a time - traveler who has come to the Pandora Hearts world to prevent a certain catastrophe from happening could make for a great story.
One idea could be a fanfic that focuses on the backstories of the minor characters in Pandora Hearts. For example, exploring the past of some of the servants in the Vessalius household. Another idea is a time - travel fanfic where a character goes back in time to change a crucial event in the Pandora Hearts story. Maybe a fanfic that imagines an alternate ending to the series, where different alliances are formed and different fates await the characters.
You could make an OC that is a half - human, half - Chain. This OC would struggle with their identity, being shunned by both humans and Chains. Their story could revolve around finding their place in the world of Pandora Hearts. They might have special abilities that neither humans nor Chains possess, which could make them a target for various factions in the story. They could also form an unlikely alliance with some of the main characters who see their potential and uniqueness.
Harry Potter and Oz Vessalius would be an interesting pair. Harry is used to facing great challenges in the wizarding world, and Oz has his own set of problems in Pandora Hearts. They could learn from each other's experiences and perhaps help each other out. For example, Harry could teach Oz some basic magic spells, and Oz could show Harry how to handle the complex social and power - related situations in his world.
You could also write a fanfiction centered around a mystery. For example, a strange event occurs in Pandora that only Break and Alice seem to be aware of. They have to work together to solve it, and during the process, their relationship deepens. As they uncover clues and face challenges, their bond becomes stronger, and new aspects of their personalities are revealed.
Well, you could have a fanfiction where Voldemort discovers the power of the Heartless and tries to use them to his advantage. The Order of the Phoenix, along with the heroes from Kingdom Hearts, would then have to stop him. Or perhaps a story in which the Hogwarts houses are somehow connected to the different worlds in Kingdom Hearts. Gryffindor could be linked to a world full of brave warriors, and Hufflepuff to a more peaceful, nature - based world.
One interesting Pandora Hearts fanfiction could be about a different take on the relationship between Oz and Alice. For example, a story where they have to face a new, unknown enemy together in a world that's a bit different from the original setting. It might explore their characters more deeply as they struggle against this new threat.
A fanfiction could explore a scenario where the Sharingan in Naruto has a connection to the power of the Pandora Hearts world. Maybe Sasuke discovers that his Sharingan has a hidden ability that is related to the power of the Chains. This could lead to a whole new arc in his character development as he tries to understand this strange connection.
One interesting 'Harry Potter Pandora' fanfiction could be about Pandora's box being found in the wizarding world and how it affects the characters. Maybe it releases all kinds of magical creatures or dark magic that Harry and his friends have to deal with.
Perhaps Voldemort discovers the power of the Heartless and tries to use them to his advantage. The protagonists from Kingdom Hearts then have to work with the Order of the Phoenix to stop Voldemort and the Heartless. The Hogwarts students could be fascinated by the Keyblades and the different worlds the Keyblade wielders have been to, and there could be a lot of cultural exchange between the two groups.