Well, one possible plot could be that Harry discovers his true heritage as the son of the Demon King gradually. He might struggle with new-found powers that are both a blessing and a curse. He could face opposition from the wizarding world who fear his demonic lineage, while also having to decide whether to embrace or reject his dark side.
One possible plot could be that Harry discovers his true heritage as King Arthur's son. This would likely throw the wizarding world into chaos as it challenges the existing ideas about his family. He might inherit some of Arthur's leadership and combat skills, which could be used to fight Voldemort in a new and unexpected way.
Maybe it's about Harry's journey to prove himself worthy of the throne.
In this fanfiction, Voldemort could also be involved in a different way. Since Harry is now the son of the Demon King, Voldemort might see him as a threat or a potential ally. Dumbledore would surely play a role too. He might be the one to guide Harry or try to keep him from fully embracing his demonic side. And there could be some magical creatures that are associated with the demonic realm, like imps or minor demons that could be characters in their own right.
Maybe the Radio Demon enters the Harry Potter universe first. It could be attracted by the powerful magic there. And then it somehow fuses with Harry Potter, giving him additional powers. Harry then has to deal with the reactions of his friends and the wizarding community while also trying to control these new powers and the influence of the Radio Demon within him. The plot could revolve around Harry's struggle to maintain his identity and use these powers for good in a world that is both familiar and now very different.
One possible plot could be that Harry discovers his half - demon heritage as he grows older. He might face discrimination from some in the wizarding world who fear his demon side. He then has to go on a journey to learn about his demon heritage and how to control the powers that come with it, all while still fighting against Voldemort or other threats in the wizarding world.
Well, perhaps the plot could involve Harry struggling with his new - found half - demon nature. He might have to hide it from his friends at Hogwarts for fear of being ostracized. And he could discover that his demon side gives him some unique magical abilities that are both a curse and a gift.
Well, one possibility could be that Harry has some sort of angelic powers inherited from Castiel. He might use these powers to fight Voldemort in ways that are different from the original story. For example, he could heal the injured more effectively during the battles.
Well, perhaps the plot could involve Harry discovering his Titan heritage and having to deal with new powers. He might struggle to balance his wizarding world life with this new Titan side. Maybe he has to face enemies that are both from the wizarding world and related to his Titan lineage.
Well, one possibility could be that Harry discovers his true parentage as Sauron's son in a very shocking way. Maybe through some dark magic revelation. Then he might struggle with his identity, being a part of the wizarding world that he loves but also having this dark connection. He could face a lot of inner turmoil as he tries to decide whether to embrace his dark heritage or fight against it.
In this fanfiction, perhaps Harry's identity as the Joker's son makes him an outcast in the wizarding world. The story could revolve around him trying to prove that he's not just a product of his 'father's' evil. He could use his Joker - like cunning and unpredictability to outwit his enemies in Hogwarts, who might be prejudiced against him due to his strange heritage.