In some fanfics, there could be a misunderstanding. Suppose Kushina did something that Naruto misinterpreted as harmful to him or his friends. This misinterpretation could lead to his hatred. For example, if Kushina was involved in a mission that Naruto thought put the village at risk, but in reality, she had no choice.
Another reason might be a personality clash. The fanfic could depict Kushina with a different personality than in the original, one that Naruto just doesn't get along with. Maybe she's too strict or too overbearing in the fanfic, and Naruto rebels against her, which eventually turns into hatred.
He may dislike it because he feels that it undermines the real struggles and achievements of the ninja. In fanfiction, things might be made too easy or unrealistic. He has fought tooth and nail for everything in his ninja life, and seeing it made into something that doesn't represent that in fanfiction would make him hate it.
One reason could be jealousy. If in the fanfic, Sakura gets closer to someone else Naruto cares about, like Sasuke in a different way than he expected, it might make him hate her. For example, if Sakura teams up with Sasuke against Naruto's wishes in the fan - created plot.
One possible reason could be jealousy. Maybe in the fanfiction, Jiraiya gives more attention to another character, and Naruto, being young and impulsive, starts to hate him for it.
Perhaps he has seen fanfiction that contains inaccurate information about the Naruto universe, such as wrong jutsu descriptions or incorrect interpretations of the ninja clans. This would make him dislike it as he is an educator in the Naruto world and has a certain standard for knowledge about it.
One reason could be jealousy. Maybe in the fanfic, Annabeth gets more attention or praise for her skills and Percy feels left out or overshadowed, which turns into hatred. Another possibility is that there's a rift caused by their different approaches to solving problems. If Annabeth's logical thinking clashes too much with Percy's more instinctive ways, it could lead to resentment.
One possible reason is that their personalities clash. Percy is often portrayed as a more outgoing and confident character, while Nico is more introverted and brooding. In a fanfic, this could lead to misunderstandings and animosity between them. For instance, Percy's bold actions might seem reckless to Nico, causing him to dislike Percy.
One reason could be that the fanfic changes the essence of their relationship. In the original, they have a certain dynamic that she values, and fanfics might mess it up.
Maybe in this fanfic, the author wants to create a unique and dark plot. Kushina might be made to hate Naruto due to some kind of misunderstanding. For example, she could be misled to believe that Naruto has some connection to a great evil that she is against.
One possible reason is a misunderstanding. If there are rumors or false memories planted in Naruto's mind, he might believe his mom did something unforgivable. For instance, if he's made to think she was involved in the death of someone he cared about.
One common reason is envy. Naruto is so highly respected and has achieved so much. Boruto, in fanfic, might envy that and turn it into hatred. Another is the generational gap. Their values and ways of doing things could be different, leading to conflict and hatred in fan - made stories.