The main character is usually the heir themselves. They could be an original character created for the fanfiction or a well - known character from the original series given a new twist. There are also often mentors from each of the houses the heir is related to. For example, a wise old Ravenclaw professor or a brave Gryffindor knight - like figure.
One interesting plotline could be the protagonist using the knowledge and resources from multiple houses to solve mysteries that stump others. For example, they might combine Gryffindor's courage with Ravenclaw's wisdom to outwit dark wizards. Another could be the social implications of being an heir of multiple houses, facing both envy and admiration from fellow students.
Well, it could be about Harry discovering he has some sort of ancient blood connection to multiple houses. Maybe he finds out that his family tree has been misread all along. For example, he could be related to the founders of Hufflepuff and Ravenclaw in some way. This could lead to him having special powers or abilities related to those houses, like being able to access their long - forgotten knowledge or having an affinity for Hufflepuff's loyalty - based magic.
Maybe a jealous student or a group of students who feel threatened by Harry's new - found status. They could be from pure - blood families who think Harry doesn't deserve to be the heir of so many houses. They might start spreading rumors and causing trouble for Harry at Hogwarts, and eventually, their actions could lead to more dangerous situations as they side with darker forces out of envy.
One possible plotline could be Harry discovering the responsibilities that come with being heir to multiple houses. For example, he might have to deal with different magical legacies and political implications within the wizarding world. Another could be how he balances the loyalties to these various houses while still remaining true to his friends at Hogwarts. Maybe he uncovers secrets about the founders of the houses that were long forgotten.
Hermione could be a main character. She might help Harry understand the implications of being heir to multiple houses. Ron could also be important as he stands by Harry through all the new revelations. There could also be characters like Draco Malfoy. If Harry is heir to Slytherin, Draco's attitude towards Harry might change significantly, adding an interesting dynamic to their relationship.
Hermione Granger would also be a great candidate. She is highly intelligent like a Ravenclaw, but her loyalty to her friends and the fight against evil shows Hufflepuff traits. Her courage in the face of danger is Gryffindor - like, and she has proven to be cunning when outwitting her enemies, which is a Slytherin quality.
One idea could be a character who has to balance the different cultures and traditions of the multiple houses they are lord of. For example, Gryffindor's courage, Ravenclaw's intelligence, Hufflepuff's loyalty, and Slytherin's cunning all come with their own sets of values and expectations.
In some fanfictions, it might be possible for Harry Potter to be depicted as the heir of Grindelwald. Fanfiction allows for a lot of creative interpretations. However, this goes against the original canon where there is no such indication.
In the fanfiction world, Harry might be the heir to Hogwarts if there was some sort of magical pact made generations ago. For example, perhaps one of his ancestors had a special role in the creation or protection of Hogwarts, and this role was passed down through the family. It could also be that his unique magical abilities, like his ability to resist Voldemort's attacks from a young age, are signs of a deeper connection to Hogwarts itself. This connection could be what designates him as the heir in the fanfiction's plot.