With Draco Malfoy, instead of the usual rivalry, Harry might be more dismissive. Raised by the founders, he would have a stronger sense of self - worth and not be as affected by Draco's taunts. He might even pity Draco for his narrow - minded views, which are in contrast to the broader perspectives he's gained from the founders.
His relationship with Dumbledore would be complex. Dumbledore is seen as a great wizard in the normal series, but Harry, raised by the founders, might question Dumbledore's actions more. He could have different ideas about how Hogwarts should be run and how to deal with the threat of Voldemort, based on what he's learned from the founders.
His relationship with Ron and Hermione would be very different. Since he's been raised by the founders, he might be more aloof from the typical Gryffindor camaraderie. He could see Ron's insecurities in a different light, perhaps being less patient with them. And with Hermione, he might be more critical of her book - learning approach as he's been taught by the founders themselves.
If Harry was raised by the founders in fanfiction, his relationship with his enemies would also change. Voldemort might see him as an even greater threat because of the knowledge and power he gained from the founders. And Harry might not have the same relationship with Dumbledore. He would be more independent and rely more on the teachings of the founders rather than Dumbledore's guidance.
His relationship with Hermione would be very different. Instead of being friends, they might be enemies at first. Since he was raised by Death Eaters, he might look down on Hermione as a Muggle - born. But as he gets to know her better, he could start to question his beliefs.
With Dumbledore, it would be a complex relationship. Dumbledore would be cautious yet intrigued by Harry. He would want to guide Harry away from the potentially dark path that his Nathrezeim upbringing could lead him to. Harry, on the other hand, might be resentful of Dumbledore's interference at first.
His friends might be initially shocked. Hermione would be super curious and want to research all about it. Ron might be a bit jealous at first, but then come around. Their adventures would be different as Harry would have new insights from the founders.
Harry's relationship with Lupin would be very interesting. Lupin, being a werewolf himself, could act as a mentor to Harry. He could teach Harry how to control his werewolf side better. And this shared experience could bring them closer together. But at the same time, Harry might feel a sense of resentment towards Lupin, thinking that Lupin could have prevented his transformation in some way.
Naruto's relationship with Kakashi would also change. Since Anko has her own way of doing things, Naruto might not be as receptive to Kakashi's laid - back teaching style at first. However, as he grows, he could come to appreciate both Anko's and Kakashi's approaches. And Kakashi might see Naruto as a more self - sufficient student compared to the original story, which could change their dynamic in terms of how much guidance Kakashi provides.
His relationship with Hermione and Ron would likely become strained at first. Since he's at a different school, they wouldn't be able to see each other as often. Hermione might be a bit jealous that Harry is experiencing a different magical education. With new friends at Beauxbatons, Harry could form a close bond with a French student who has a very different view on magic. This new friend could introduce Harry to new spells and ways of thinking that he hadn't considered before.
His relationship with Ron would be very different. Ron might be initially distrustful or even hostile towards Harry in Slytherin. But as the story progresses, they could come to understand each other better. Harry's relationship with Hermione could also change. She might be more cautious around him at first, but then realize that Harry is still the same person deep down. And his relationship with Draco would be much more complex. They could start as rivals, but then become allies in some situations, as they both have a connection to Slytherin.
His relationship with the teachers would also be different. Snape, for instance, might be more conflicted about Harry. On one hand, he's in Slytherin which Snape favors, but on the other hand, he's still Harry Potter. And Dumbledore would have to watch Harry from a different perspective, perhaps guiding him in a more subtle way to make sure he doesn't get too influenced by the darker aspects of Slytherin house.
His relationship with his enemies like Voldemort would also be affected. If Regina has some sort of power or influence over Harry, Voldemort might see him as an even greater threat or an easier target. Harry might also have different ways of defending himself, influenced by Regina's methods or the new environment he's in. For example, Regina might have her own way of dealing with dark magic that she teaches Harry, which changes how he approaches Voldemort and his Death Eaters.