In this fanfiction, the plot could be that Harry discovers some dark secrets about the wizarding world that make him see everyone in a different light. He finds out that many of the people he trusted were involved in some sort of cover - up or unethical behavior. This revelation makes him turn against them all. He then sets out on a journey to expose these secrets and take revenge on those who have wronged him, all while hating everyone around him.
Perhaps the plot could revolve around a magical accident or curse that makes Harry lose his ability to feel positive emotions towards others. As a result, he starts to hate everyone. He begins to act out against the people he once cared about, causing chaos in Hogwarts and the wider wizarding community. His friends would be shocked and try to find a way to reverse the effect, but Harry would resist their attempts.
Maybe Harry has had some really bad experiences that made him bitter towards everyone. For example, he could have been betrayed by his friends multiple times.
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.
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.
Perhaps in this fanfiction, Naruto discovers some dark secrets about the village. Secrets that make him feel like he's been used all along. Like the village was only using him as a weapon against their enemies. This realization could make him resent everyone in the village, thus hating everyone.
Well, it could be that Percy has had some really bad experiences in his life that made him bitter towards everyone. Maybe he was betrayed by friends in the past, so now he just can't bring himself to trust or like anyone.
It's possible that the plot could start with some kind of mind - control or brainwashing of Harry. Then, he would start to spread hatred towards Mudbloods in Hogwarts. This would cause a great divide among the students. There could be battles between those who support Harry in his new - found (but false) beliefs and those who oppose him. But again, this is a very dark and untrue - to - the - original - spirit plot that goes against the core values of acceptance and friendship in the Harry Potter series.
Well, perhaps in this fanfic, Harry could be wrongly accused of a serious crime like dark magic use. Everyone, including his friends Hermione and Ron, might turn their backs on him due to false evidence. He would then have to fight alone to clear his name and find out who really framed him.
One possible plot could be that there is a powerful, but corrupting magical artifact in the story. Harry comes into contact with it and it starts to warp his views. He begins to show disdain for those considered mudbloods. But as the story progresses, his true friends try to show him the error of his ways and help him regain his original, inclusive self.
In such a fanfiction, it could be that Harry Potter has been corrupted by a powerful and malevolent force. This force might have warped his sense of right and wrong. It could also be that the author wants to explore the extreme consequences of power and how it can turn a hero into a villain. For example, if Harry Potter was constantly taunted and mistreated by the wizarding community despite all he has done, he might reach a breaking point and lash out at everyone.
Well, perhaps in this fanfiction, Harry has been through so much that he decides to isolate himself from everyone. He might be tired of the constant danger and the expectations placed on him. So he shuts out his friends like Ron and Hermione, and just focuses on his own inner journey, maybe to discover some new magic that he believes can only be found in solitude.