Yes, in some fanfictions, Harry Potter is depicted as the heir of Gryffindor. It adds an interesting twist to the original story. The connection to the Gryffindor sword becomes more profound as it is often a symbol of Gryffindor's legacy. In these fanfictions, Harry might discover hidden powers or a deeper understanding of his destiny through this new identity.
Another challenge is in his relationships. He may worry that people pity him or treat him differently because of his blindness. For example, in some fanfics, he has to prove to Lily that he's still the same James she knew before, just with a new disability to deal with. Also, in duels or battles, not being able to see his opponents' movements directly puts him at a disadvantage, so he has to develop new strategies to defend himself.
Perhaps it's a character from a minor magical family that was thought to be extinct. Their heir could have powers that are a combination of ancient magic that was thought to be lost. They might have the ability to communicate with magical creatures in a way that no human has been able to do before, which would make them very powerful in the eyes of both those who want to protect magical creatures and those who want to use them for their own gain.
It could be Harry Potter himself. Since he has so many special qualities and a deep connection to Hogwarts, he might be revealed as an heir. Maybe he has some latent powers related to one of the founders that haven't been discovered yet.
He could meet the descendants of his friends, like the grandchildren of Ron and Hermione. They might show him around the future wizarding world and tell him about all the changes that have occurred. Also, he may run into some new and powerful wizards who have emerged in the future and learn from them about new magical techniques.
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.
It could be a previously unknown character, like a distant relative of one of the main families in the Harry Potter series. Maybe a long - lost cousin of the Weasleys or a descendant of one of the founders of Hogwarts that has been living in hiding.