Perhaps in the fanfic, Narcissa adopts Harry because she has a change of heart after seeing the destruction Voldemort causes. She wants to protect Harry as a way to atone for her family's association with the Dark Lord. Harry would then grow up in a Slytherin - influenced environment but still hold onto his Gryffindor values. This would lead to interesting interactions with other Slytherins and a different dynamic within Hogwarts.
Well, perhaps the plot could involve Rias Gremory taking Harry Potter under her wing in a world where the two fictional universes collide. She might use her devil powers to protect Harry from the threats in the wizarding world that Dumbledore couldn't handle. Harry could also learn some new skills from the devilish side of things, like enhanced combat abilities.
Well, perhaps it could start with Bella Swan finding little Harry Potter in a strange situation, like he's been magically transported to her world. She decides to take him in out of kindness. Then, she might have to deal with the magical aspects of Harry's world that she doesn't understand at first. Maybe she tries to protect Harry from the threats in his own world using her own unique skills.
One possible plot could be that Harry grows up with a different perspective on the wizarding world. Narcissa might shield him from the more extreme pure - blood ideologies in her own family. He could still have his natural talent for magic but be trained in a more Slytherin - like way, focusing on cunning and self - preservation. And he might have a different relationship with Draco, perhaps more of a brotherly bond.
Harry would likely become more confident in his pure - blood heritage. Growing up with Narcissa, he'd be exposed to different values and traditions, which could make him more well - rounded. He might also be less impulsive as he'd be in a more controlled environment.
Well, one possibility could be that Narcissa sees potential in Fem Harry Potter and trains her in the ways of pure - blood magic and etiquette. Maybe she wants to use Harry as a pawn in the wizarding world's power games. Or it could be that Narcissa, having lost Draco in some way, sees Harry as a surrogate to redeem herself. Another idea is that she trains Harry to fight against the Dark Lord from the shadows, using skills that only the Blacks possess.
A plot twist could be that the magic within Harry starts to have an impact on the Cullens' immortality. It could either strengthen it in some strange way or put it at risk. Another interesting twist would be if the Cullens have to hide Harry not only from the wizarding world but also from other vampire clans who see him as a threat or a valuable asset due to his unique magical powers. And what if Harry starts to develop a new kind of magic that is a blend of wizardry and something influenced by the Cullens' vampire nature?
In a 'Percy Jackson adopts Harry Potter' fanfic, the plot could start with Percy being on some kind of mission that crosses into the wizarding world. He stumbles upon Harry, who is alone and vulnerable. Percy decides to adopt Harry because he sees the same kind of determination and courage in Harry that he has. As they journey together, they exchange knowledge. Percy teaches Harry about Greek mythology and combat skills, while Harry shares his knowledge of magic. They form a bond that helps them face threats from both magical and mythological creatures, and they might even team up to fight against a common enemy that is a threat to both their worlds.
The plot could involve Rosalie sensing that Harry has a special power that is not just related to his wizardry. She decides to adopt him to keep him safe from the dark forces in both the wizarding world and the vampire world. Rosalie would have to deal with the magical aspects of Harry's life that she doesn't fully understand at first. But with time, she helps him hone his skills. Harry, in turn, might introduce Rosalie to the concept of love and friendship in a way that vampires don't usually experience. This could lead to a change in Rosalie's view of the world and her place in it.
The fanfic could center around Harry's life outside of the main events of the books. For example, it could explore his summer holidays in more detail. He could be spending time in the Muggle world and using his magic in creative ways to solve normal, everyday problems. He might use magic to help his neighbor fix a broken fence without the neighbor realizing it was magic. This would add a new dimension to his character and show how he can adapt his magical abilities to different situations.
One possible plot could be that Harry discovers a young Tom in a difficult situation, perhaps an orphanage similar to his own past. He decides to take Tom under his wing out of a sense of empathy. Harry then tries to guide Tom away from the dark path he originally took in the canon. For example, he might introduce Tom to the world of positive magic and friendship early on, which could change Tom's perspective on life and magic.