One possible reason could be a misunderstanding. Maybe some false information was spread about his mother, making Naruto believe she had abandoned him. Another reason could be related to the secrecy around his mother. If he grew up feeling alone and not knowing about her, he might develop resentment.
In some fanfictions, Naruto might be made to hate his mother because of a misinterpreted prophecy or a false belief that she abandoned him. Maybe the author wants to create a more complex and angsty story line for Naruto.
One possible reason could be jealousy. Maybe his brother has some special abilities or gets more attention that Naruto feels he should have. For example, if his brother is really good at a certain jutsu and is always praised for it while Naruto struggles, that could lead to resentment.
One possible reason could be misinformation. Maybe in the fanfiction, Naruto was told false stories about his mother that made him dislike her. For example, if he was told she abandoned him for some untrue reason.
It could be a misunderstanding. Perhaps Naruto was involved in an incident where his actions were misinterpreted by his brother. For example, Naruto might have accidentally caused harm to someone his brother cared about while trying to do something good, and his brother didn't get the full story and started to hate him as a result.
This fanfiction changes the emotional core of Naruto's journey. His growth in the original was often tied to his connection with his parents' legacy. Here, it becomes about overcoming his hatred for his mother. It also affects his relationships with others. For example, how he interacts with characters like Jiraiya who knew his mother might be very different.
It could be that the 'mother love' in the fanfiction goes against Naruto's own ideals or his perception of family. Naruto grew up without his parents, and if the fanfiction presents a mother love that is forced or not in tune with his experiences, he might hate it. He has his own understanding of love and family through his friends and the village, and this fanfiction concept could be a jarring deviation from that.
One reason might be that he doesn't like how fanfiction can change the relationships between characters. For example, in the original, his relationship with Naruto is based on training and mentorship, but fanfiction could make it something completely different.
In this fanfiction, it could be that Naruto's parents were under some sort of mind - control. Some evil entity could have taken over their minds and made them feel hatred towards Naruto. Also, it might be related to a family secret or feud. There could be something in the family's past that made them believe Naruto was a stain on their family name, even though Naruto himself was innocent. It could also be a case of false information being spread around the village which made his parents believe lies about him.
In fanfiction, Naruto hating his sister could be due to various reasons. Maybe the writer wants to create a new and complex dynamic. However, in the original Naruto series, Naruto doesn't have a sister, so it's all fictional creation. It could be that the sister character is written to have done something really bad to Naruto or his friends, which makes him hate her in that particular fan - made story.
Another reason might be related to family politics. In some complex family structures in the Naruto universe, there could be different factions. Naruto might be on the wrong side of the power struggle within the family. His views or actions could be seen as a threat to the traditional power structure of the family, so they hate him.