Well, if Harry Potter is reborn as Percy Jackson, perhaps his relationship with the gods would be unique. Since he has experience with a different kind of magic system, he might question the Greek gods' ways more. He could try to introduce some of the more organized aspects of the wizarding world, like the Ministry of Magic's rule - making, to the rather chaotic world of the demigods.
A possible plot could be that a powerful Godlingg artifact is discovered that has the potential to destroy both the wizarding world of Harry Potter and the demigod world of Percy Jackson. Harry and Percy, along with their friends, must race against time to find and secure the artifact before it falls into the wrong hands.
One interesting plot could be that the magical worlds of Hogwarts and Camp Half - Blood somehow merge. Harry Potter and his friends find themselves in the world of Percy Jackson, facing off against mythological creatures they've never seen before. Maybe they have to work together to stop a common enemy that threatens both their worlds, like an ancient dark magic that is starting to corrupt the gods and the wizards alike.
Well, he might bring his demigod skills to Hogwarts. He could be really good at Defense Against the Dark Arts, using his combat experience from fighting monsters. And his ability to adapt quickly, which he had in the Percy Jackson world, would help him in the wizarding world too.
Perhaps Percy gets a strange magical summons to Hogwarts, and there he meets Harry. They figure out they're cousins. They then start to explore their family history together. Along the way, they realize that an ancient evil has been targeting their family for generations and they must use both magic and demigod powers to stop it. They also have to deal with the cultural differences between the two worlds, like Percy being used to the more physical and outdoorsy battles while Harry is more accustomed to spell - casting duels.
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 settings are different. Harry Potter is set mainly in the UK, at Hogwarts School of Witchcraft and Wizardry and other wizarding locations. Percy Jackson is set in modern - day USA, with a lot of action taking place at Camp Half - Blood. Also, the magic systems vary. In Harry Potter, there are spells, potions, and magic wands. In Percy Jackson, the demigods have powers related to their godly parentage like Percy can control water because his father is Poseidon. So they are clearly not related in a fanfiction way.
Well, a major plot twist could be Naruto being reborn as Percy but still having some of his past life memories. This would lead to him trying to find other reincarnated ninjas in the Percy Jackson universe. Maybe he thinks there are other shinobi reborn as demigods too. Also, his knowledge of seals could be used in a really unique way. He could create seals that interact with the magic in the Percy Jackson world, like sealing away monsters in a way that the demigods have never seen before.
If Harry Potter was a god in Percy Jackson fanfiction, it would mean a huge shift in the power dynamics. He would have abilities far beyond his normal wizarding skills. He could potentially control aspects of nature or fate, like the native gods in Percy Jackson. It would also change the relationships between him and the other characters from both series. For instance, Percy might view him with a new level of respect or fear.
One possible interesting plot could be that the magic from the Harry Potter world starts to seep into the Percy Jackson universe, causing chaos among the demigods. For example, Hogwarts could suddenly appear in the middle of Camp Half - Blood. The demigods, not used to this type of magic, would be both curious and threatened. Meanwhile, Harry and his friends could get accidentally transported to the Percy Jackson world and have to team up with the demigods to figure out how to send Hogwarts back and restore the balance between the two magical systems.
A possible plot is that Voldemort discovers the existence of the demigods and tries to use their powers for his own evil purposes. He sends his Death Eaters to capture some demigods. Percy and his friends manage to escape and seek refuge at Hogwarts. At Hogwarts, they learn about magic in a whole new way while also teaching the wizards and witches about their own powers. The two groups then have to combine their skills, like the demigods' combat abilities and the wizards' spell - casting, to fight against Voldemort and his new - found allies from the world of Greek mythology.