A plot idea could be that Harry's reincarnation as Salazar is part of a grand prophecy. As he uncovers this truth, he realizes that he has a greater role to play in the wizarding world. He might start to gather followers who believe in the old ways of Salazar. This could cause a division in the wizarding community, with some seeing Harry as a savior and others fearing that he will bring back the dark and exclusionary ways of Salazar. Harry would then have to decide how to use his new identity for the good of all wizards.
One plot idea could be that Harry starts having strange memories of Arthur's life. He might remember Arthur's relationships, like his bond with his family. This could lead to Harry trying to understand these memories and how they relate to his current life in the wizarding world. Another idea is that Harry discovers he has some of Arthur's skills, such as an affinity for working with magical devices like Arthur had with Muggle artifacts. It could create a whole new dynamic in his relationships with his friends and teachers as they try to figure out what's going on with him.
Maybe Harry time - travels back to the time of Salazar Slytherin. He has to navigate the complex politics and magic of that era. He might end up befriending Slytherin and changing the course of Hogwarts' history. This could lead to a Hogwarts that is different in many ways, like having a more unified house system earlier on.
Well, perhaps Harry, as the reincarnation, has the ability to bring back some of the long - lost traditions of the founders. For example, he might re - introduce a forgotten form of magic taught only in the founders' time. And he could face opposition from some in the wizarding world who fear change or are jealous of his new - found connection to the great founders.
In this fanfiction, an exciting plot could be Naruto's encounter with the Dark Arts. Given his strong will and positive nature, he might have a unique way of combating dark wizards. He could use his sage mode to sense the presence of dark magic and his Rasengan could be transformed into a powerful anti - dark magic spell. His relationships with the characters from Naruto could also be mirrored in the Harry Potter world. For instance, he might see Ron as similar to Shikamaru, in terms of being a laid - back but reliable friend, and Hermione as a bit like Sakura, smart and strong - willed.
Well, perhaps Sasuke's reincarnation is sought after by Voldemort. Voldemort hears rumors of a powerful being with strange and unknown powers (Sasuke's Sharingan and ninja skills). So he tries to either recruit or eliminate Sasuke. Sasuke, on the other hand, is more interested in finding out the secrets of magic in this new world and how it relates to his own past powers. He might form an unlikely alliance with Harry Potter to resist Voldemort, as they both have unique powers that the Dark Lord fears.
One plot idea could be Harry struggling to fit in at first in Slytherin because of the house's reputation for dark magic, but then he discovers the true values of loyalty and cunning within it. He could form an unlikely friendship with a pure - blood Slytherin who helps him see that not all in Slytherin are bad. Another idea is that Harry uses his newfound Slytherin traits to outwit Voldemort in a different way than in the original story, perhaps by using more stealth and manipulation.
Perhaps Harry is adopted by a Muggle family who are aware of the wizarding world. They could be a family of scientists who study magic from a scientific perspective. Harry would grow up with a unique understanding of magic, seeing it both as a wonder of the wizarding world and something that can be analyzed. This might make his time at Hogwarts very interesting as he tries to blend these two views of magic.
One plot idea could be that Harry is framed by a powerful dark wizard who has infiltrated the Ministry of Magic. The wizard plants false evidence that makes it seem like Harry has committed a serious crime against the wizarding world. Harry then has to use his wits and the help of his true friends, like Hermione and Ron, to find a way to prove his innocence while being held in a magically fortified prison.
One idea could be Harry being raised by the Weasleys from a very young age. He'd grow up with their large family dynamic, learning magic in a more chaotic but loving environment. It might change his personality a bit, making him more outgoing and confident earlier. Another plot could be him being raised by Remus Lupin. Lupin would instill in him a deep understanding of the dark arts in a more academic way, and also teach him about acceptance of his own lycanthropy - like condition if he were to inherit it. And a third idea is Harry being raised by the centaurs in the Forbidden Forest. He'd learn their unique brand of magic, which is more in tune with nature, and have a different perspective on the wizarding world and its relationship with the natural world.
One idea could be that Harry, as Voldemort's soulmate, tries to use their connection to redeem Voldemort. He might show Voldemort memories of love and kindness in an attempt to change his dark ways.