Yes, it's a popular enough concept in the fanfiction community. Writers may be drawn to this idea as it allows for a lot of new plot developments. For example, it could change how Harry's relationship with the wizarding world is perceived. His connection to Voldemort in this way might make him an outcast in new and different ways than in the original story, and also open up possibilities for different kinds of magical powers or inheritances.
One possible plot could be that Harry discovers the truth about his heritage as he gets older. This causes a huge upheaval in the wizarding world. His friends might be initially shocked and some might even turn against him. Harry then has to struggle to prove that he's not like Voldemort while also trying to understand his new - found identity.
Yes, in certain fanfiction stories, Harry is depicted as Voldemort's heir. This might be because the authors want to explore a different kind of relationship between them. For example, they could use this concept to show how Harry has to struggle with an inner darkness that he inherits from Voldemort, which makes his character development more complex and interesting.
In the realm of fanfiction, many out - of - the - box concepts are explored. While the idea of Harry being Voldemort's son and heir goes against the original 'Harry Potter' narrative, in fan - created stories, it might be used to create a whole new plot. For example, it could lead to a story where Harry has to struggle with his identity, being both the 'Chosen One' and the heir of the Dark Lord. It could also introduce new power dynamics and character relationships, as characters would have to re - evaluate their feelings towards Harry. Maybe some characters would try to use Harry's newfound heritage for their own gain, while others would try to help him come to terms with it.
His relationship with Hermione and Ron would be strained at first. They would be confused and a bit scared. But as they see Harry resist the dark side, they would become more supportive. With Dumbledore, there might be a new level of secrecy and mistrust at the start, but Dumbledore would likely keep an eye on Harry to see how he develops. As for the other students, many would be afraid and avoid him, but some might be curious and try to befriend him to see what it's like to be around the heir of Voldemort.
One possibility is that the wizarding world would be in an even greater state of turmoil. The Order of the Phoenix might be suspicious of Harry, and the Death Eaters could try to manipulate him into joining their side. Harry would also have to deal with his own identity crisis, not knowing how much of his actions are his own and how much are influenced by his connection to Voldemort.
One possible plotline could be that Harry has to hide this fact from his friends at Hogwarts, fearing their reaction. He might struggle with feelings of guilt and confusion, especially if he starts to show some of Voldemort's darker tendencies.
Another possible candidate in fanfictions could be Neville Longbottom. He has a deep connection to the magical world and shows great courage and growth throughout the series. His latent magical abilities, which are finally fully realized, could be interpreted as him being an heir of Merlin in a way. He has the potential to be a great wizard, just like Merlin was.
Harry could become more powerful in a way that scares his friends. Voldemort's training might focus on the Dark Arts, which are powerful but dangerous. This could change Harry's magic style. He may become more solitary as his new skills and knowledge set him apart from his Hogwarts friends who follow a more traditional path of magic.
It's possible. In the realm of fanfiction, the imagination knows no bounds. Writers might come up with such a scenario for various reasons, perhaps to explore a different side of the characters' relationships. But it's not a common or mainstream concept within the Harry Potter fanfiction community, as it goes against the typical character dynamics we expect from the series.