Well, it could be due to their different personalities. Naruto is all about hard work and loyalty to his friends in his own universe. Rias Gremory has a more complex and sometimes manipulative personality in her story. In fanfiction, the writer might want to create a conflict by making Naruto dislike her, perhaps because he sees her methods as being at odds with his own values.
Maybe it's a matter of worldviews. Naruto comes from a world where ninjas have a certain code. Rias is from a world of devils and different power dynamics. Fanfiction writers might explore how Naruto, with his straightforward and determined nature, would react negatively to Rias's more conniving or power - hungry aspects, leading to his hatred in the story.
It could be that the OC creator simply doesn't like the typical tropes or storylines often found in Rias fanfiction. For example, if the fanfictions tend to be very formulaic or over - use certain clichés, the OC might be a symbol of a break from that. Also, perhaps the OC has a specific backstory or purpose that is at odds with the general narrative of Rias fanfiction.
Maybe the OC has a completely different personality or set of values from what is often portrayed in Rias fanfic. It could be that the OC has had bad experiences related to the typical tropes or themes in those fanfics.
One potential plotline could be Naruto being summoned to the world of Rias by accident. He then has to figure out how to get back home while also getting involved in the power struggles within the devil world. Maybe he becomes a key player in a battle for control of a certain territory.
In a Naruto and Rias Gremory fanfiction, Naruto's chakra system could interact in interesting ways with the magic in Rias's world. His ability to control and manipulate chakra might be seen as a form of power that the devils would either fear or try to understand. Rias, on the other hand, could introduce Naruto to the political and social aspects of her world. They could also exchange combat techniques, with Naruto showing the devils how to move with the speed and stealth of a ninja, and Rias's group teaching Naruto some devil - specific magic that could enhance his abilities in different ways.
One possible idea for this fanfiction could be Naruto being transported to the world of High School DxD. He might end up attending the same school as Rias. Given Naruto's strong sense of justice and his combat skills, he could quickly become involved in the supernatural battles and power struggles in that world. He might also form an interesting relationship with Rias, perhaps starting as friends and gradually developing into something more as they face various challenges together.
Maybe Naruto has his own set of values and the concepts in Rias fanfiction go against them. He's from a different fictional universe with its own rules and ethics, and the ideas in Rias fanfiction might seem out of place or even wrong to him.
Maybe he hates it because it often distorts the real ninja world he knows. Fanfictions might create false or out - of - character scenarios that he can't stand.
Maybe Naruto is a character with a focus on his own ninja journey and goals. Love fanfiction might deviate from his core identity in the original story, so he 'hates' it.
Perhaps Naruto fans who are into the Naruto story for its action, ninja skills, and complex relationships within the Naruto world find Aphrodite fanfiction to be a distraction. Naruto is a character with a very specific identity and purpose in his own story, and introducing Aphrodite from a different mythology into his fanfiction might seem like a forced and inappropriate mash - up.
It could be that the essence of Naruto's character is often misrepresented in Superman fanfiction. Naruto is about hard work, friendship, and achieving one's dreams through personal growth in his own story. When put into Superman fanfiction, his character might be forced to fit into plots that don't align with his original values, which could lead to the idea that he 'hates' such fanfiction.