One idea could be a crossover where a character from Naruto ends up in the Rosario + Vampire world and meets Kuyo. Maybe Naruto himself gets sent there due to a strange jutsu gone wrong. He could be confused by the different rules and powers in that world, and Kuyo might initially see him as a threat or an interesting new addition.
Well, it depends on the writer's creativity. Maybe Naruto is drawn into the Rosario Vampire world where he meets Kuyo. Naruto's ninja skills and determination could clash with Kuyo's devious vampire ways. The Rosario Vampire characters would be caught in the middle. For example, Tsunade from Naruto could end up treating vampire wounds, while Inner Moka could teach Naruto some vampire - like stealth moves in a strange turn of events.
In a fanfiction, Kuyo could interact through a trade of knowledge. The Naruto characters are known for their unique jutsus and combat strategies. Kuyo could be interested in learning some of these in exchange for his own knowledge about the supernatural world of Rosario + Vampire. He could also share his knowledge with Rosario + Vampire characters about different powers and how to control them better.
It's really hard to say. Naruto has a lot of powerful jutsu and great combat experience. But Kuyo has vampiric powers which can be very dangerous. If Naruto can get in close and land a powerful Rasengan, he might win. However, Kuyo could use his speed and fangs to counter. It really depends on the situation and how the writer wants the story to go.
I'm not sure if there is such a specific fanfiction where a character from Rosario Vampire is reading Naruto fanfiction. Fanfiction can be very diverse, but this seems like a rather unique and specific concept. It's possible that it might exist in the vast realm of fan - created stories, but it would be quite difficult to find without a more targeted search.
One possible fanfiction could involve a crossover between Rosario Vampire and Arrancar. The unique powers and characteristics of both vampires and arrancar could create interesting plotlines. For example, a Rosario Vampire character might encounter an arrancar and initially mistake them for a normal vampire. This could lead to a series of misunderstandings and battles as they figure out each other's true nature.
The novelization of Rosario Vampire is a great read. It stays true to the core elements of the source material while introducing new elements that enhance the narrative. It's a must-read for fans of the series.