Perhaps Harry has seen the worst in people too often. He might have witnessed so much greed, envy, and cruelty among those around him that he has lost all faith in humanity and thus hates everyone. He could be in a situation where he feels completely alone and that no one truly understands him.
In some fanfics, the idea of Naruto hating Hinata might be a plot device to create drama. Maybe the writer wants to explore a different kind of relationship dynamic than the canon one. It could also be that the writer has a unique interpretation of the characters' personalities and how they might clash in certain situations.
Maybe it's because Aphrodite's powers and the way she uses them are at odds with Naruto's own beliefs. Naruto believes in self - improvement through training and facing challenges head - on. If Aphrodite uses her love - related powers in a way that seems unfair or goes against Naruto's sense of justice in the fanfic, he would dislike her. Like if she uses her powers to manipulate people's emotions for her own gain, which is something Naruto would oppose.
Dumbledore could also be an important character. He might be the one who tries to figure out what's wrong with Harry and tries to reverse this hatred. Another character could be Snape. He might see this as an opportunity to make Harry's life even more difficult or, on the other hand, might be secretly trying to help him get over this hatred.
The relationships would be completely different. Instead of the usual friendships and rivalries, there would be a lot of hostility. For example, his relationship with Bakugo would be even more strained. Normally, there's a complex dynamic between them, but with Izuku hating everyone, it would be all - out enmity.
Another aspect could be the general discrimination in the BNHA society. The fact that society is so focused on quirks and those without are often looked down upon might have made Izuku bitter. He could be hating everyone because he sees the society as a whole being corrupt and unkind, not just the individuals who directly wronged him.
Well, it could be that Naruto has been betrayed too many times. Maybe he discovers that some of his closest friends have been using him all along for their own gains. So he starts to hate everyone, and the story could be about his journey of isolation and self - discovery as he tries to come to terms with his new feelings.
Often in these fanfics, Sakura might make fun of Naruto's dreams or goals in a very mean - spirited way. This constant put - down could lead Naruto to hate her. Also, if Sakura were to side with Naruto's enemies in the fanfic for some reason, like being brainwashed or having a hidden agenda, it would be a likely cause for Naruto's hatred.
Well, this kind of fanfiction might be an interesting take on the character. It could explore a darker side of Harry Potter that we don't often see in the original series. Maybe the author wants to show how all the pressure and trauma he has endured could lead to a more cynical view of those around him.