Naruto might dislike fanfiction because it can be a source of misinformation. Fans who read fanfiction might get the wrong idea about him or his world. He wants people to understand his story as it was originally intended. The original Naruto story is a carefully crafted narrative about ninja life, dreams, and the pursuit of peace. Fanfiction can deviate from this and make it seem like something else entirely, which he would find unacceptable.
One reason could be the clash of cultures. Naruto is set in a feudal Japanese - inspired world with its own unique culture, while Aphrodite is from Greek mythology. The two cultures are very different, and combining them in fanfiction might feel jarring and not in line with the essence of Naruto.
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.
It might be because of their moral values. Devils are often associated with evil and chaos in fictional stories. Naruto, who stands for good and order, would dislike them due to this fundamental difference. For instance, if devils in the fanfiction are shown to cause destruction and harm without any remorse, Naruto would surely hate them.
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.
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.
Maybe Percy has a different set of values. He might be more into peace and stability rather than the chaos and violence often associated with the hunt. In fanfiction, the hunt could be depicted in a way that goes against his moral code.
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.
Tony Stark may dislike Avengers fanfiction because it can mess with the emotional core of the team. The real relationships between the Avengers are deep and complex. Fanfiction might simplify or distort these relationships. For instance, his friendship with Steve Rogers has many layers, and fanfiction could make it into something that doesn't do justice to their real bond. Also, he's a man who values his privacy to an extent. Fanfiction might delve into his personal life in ways that he doesn't appreciate, making him feel exposed and misrepresented.
She may not like the false interpretations of Batman in some fanfictions. Fanwriters might change his personality or motives, and as a fellow hero, she doesn't appreciate that.