There might be a Rosario Crossover Fanfiction that combines Rosario's world with a fantasy realm. For example, Rosario enters a magical land full of elves and wizards. This allows for new relationships to form and adventures to unfold as Rosario has to adapt to a completely different environment.
A common type of Rosario Crossover Fanfiction involves Rosario crossing over with a superhero universe. Imagine Rosario having to team up with superheroes to fight a common enemy. This brings in the contrast between Rosario's own powers and those of the superheroes, leading to some really exciting action scenes.
A great plot idea could be a tournament - style story. Characters from Rosario Vampire and the other fandom are forced to participate in a tournament where they have to fight each other. But as the tournament progresses, they start to realize that they have more in common than they thought and might need to work together to stop the tournament from being a tool for a greater evil. Another plot could be a time - travel crossover. A character from Rosario Vampire travels back in time in the world of the other fandom and has to prevent an event that would have a negative impact on both worlds. And, a simple yet interesting plot could be a cultural exchange where the characters learn about each other's cultures, like the different vampire clans in Rosario Vampire and the unique social structures in the other fandom.
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.
In this type of fanfiction, it could start with a strange magical artifact in the Naruto world that has a connection to the Rosario world. When Naruto touches it, he and some of his comrades are transported to the Rosario world. There, they are mistaken for enemies at first. But as they show their good intentions, they start to work together with the Rosario characters. They might learn about different forms of power like the Rosario vampires' unique abilities and combine them with their own ninja skills to face challenges in this new world.
Crossovers between 'Sherlock' and 'Elementary' can be interesting too. Imagine Sherlock Holmes from the BBC's 'Sherlock' and Joan Watson from 'Elementary' working together on a case that spans both their versions of New York City. It would be a clash of different interpretations of the classic characters.
A possible plot could be that a powerful artifact in the Rosario Vampire world is being targeted by both Hollows and some rogue vampires. Ichigo and Tsukune find themselves on a quest to protect it. Along the way, they encounter various challenges and meet different characters from both universes. The cultural shock between Ichigo's world of Soul Reapers and Tsukune's world of monsters and humans could also add some comedic and interesting elements to the story.
One popular trope is the 'powerful - being - in - a - human - world' trope. Since both Rosario Vampire and Witchblade involve supernatural elements, fanfiction often plays with the idea of these powerful characters (vampires, witches, etc.) trying to fit into or interact with the normal human world. Another is the 'forbidden love' trope, as Rosario Vampire has a lot of complex relationships that can be explored further in fanfiction.
The theme of friendship within the Rosario Vampire world is also quite common in Moka - related fanfictions. Moka's friendships with other characters like Kurumu, Yukari, etc., are explored. How they support each other through various challenges in the school, whether it's dealing with other supernatural creatures or facing academic difficulties, is often a part of these fanfictions.
One of the most popular crossover scenarios might be the ones that involve unique power combinations. For example, in a Naruto and Highschool DxD crossover, Naruto's jutsu combined with the devil powers in Highschool DxD could create really interesting battles. In a Rosario Vampire and Highschool DxD crossover, the different types of supernatural beings from both series could interact in new and exciting ways. Also, crossovers that explore the different school settings and how the characters from each series adapt to them are quite popular.
One idea could be that the main characters from Rosario x Vampire end up in an alternate universe where they have to face new challenges based on the rules of the other fandom. For example, they might encounter different types of supernatural beings with unique powers.
One common theme is power combination. For example, Naruto's chakra - based powers combined with the unique abilities of the Rosario + Vampire characters like Tsukune's vampiric powers. Another theme is cultural clash. Naruto comes from a ninja - based culture, and when he enters the Rosario + Vampire world, there are differences in values, social structures, and fighting styles that create interesting scenarios.