Maybe it's about Harry's journey to prove himself worthy of the throne.
There are several possible plots. One could be that Harry has been hidden away all his life as the king's son, and now he has to suddenly step into the role of a prince. He might face challenges like learning the ways of the court, dealing with political intrigue, and facing enemies who don't want him to succeed. Another possibility is that his mother was not of noble birth, and he has to fight against the prejudice of the court. The story could also be about his adventures outside the kingdom, where he uses his status as the king's son to make a name for himself, or he could be on a quest to find a long - lost heirloom of the kingdom that is crucial for his future as the heir to the throne.
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.
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 twist could be that Harry has hidden magical abilities passed down from Regulus that no one expected. Maybe he can communicate with certain magical creatures in a unique way.
Perhaps Harry discovers his true parentage and has to deal with new powers related to Aphrodite, like charm and beauty - based abilities, while also trying to fit into the world he already knew.
The plot could involve Harry learning about his true mother. Hestia, being a rather different kind of mother figure compared to Lily Potter. His relationship with other characters might change as a result. For example, he might have a different connection to the Gryffindor common room which is associated with the idea of home, since Hestia has ties to that concept. He could also have some new abilities or a different magical aura that sets him apart from the original Harry Potter story.
One possible plot could be that Harry discovers his true heritage as Klaus' son. This could lead to a whole new set of powers and abilities for him, as well as a new family dynamic. Maybe he has to navigate the vampire world while still dealing with his wizarding roots. He could face challenges from both the wizarding community who are suspicious of his newfound vampire side, and the vampire world which might not fully accept him because of his wizard heritage.
Well, the plot could start with Harry finding out his true parentage. This would be a huge shock considering his normal 'muggle - born' or other normal origins in the original story. He might struggle with the new - found knowledge and the implications it has. Maybe he would have to deal with new powers that come with being Lucifer's son, and face opposition from both the wizarding world who see Lucifer as an evil entity and also from Lucifer's enemies in his own realm.
One possible plot could be Naruto growing up in the Saiyan world with King Vegeta as his father. He would have to deal with Saiyan politics and rivalries while also having his own ninja - like abilities from his Naruto side. Maybe he would try to unite the Saiyans in a different way than in the original Dragon Ball story, using some of Naruto's ideals of friendship and perseverance.
One possible plot could be that the OC, as the son of King Cold, struggles to live up to his father's fearsome reputation. He might be conflicted between following in his father's tyrannical footsteps or forging his own path of redemption and justice in the universe.
A possible plot twist could be that Merlin is not actually dead but has been trapped in a different dimension. Harry, as his son, has to find a way to free him. This would completely change the dynamic as they could then fight side by side against the forces of evil.