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.
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.
The plot might involve a threat that endangers both Naruto's world and the world of Rosario Vampire. Naruto, with his Kyuubi - enhanced abilities, teams up with the vampires and other creatures in Rosario Vampire. They'd have to combine their different powers, like Naruto's Rasengan and the vampires' super strength, to fight against the common enemy. It would be a wild mix of ninja action and vampire drama.
Naruto would probably be very curious about the vampires and other creatures in Rosario Vampire. He'd be his usual friendly self, trying to make friends. The vampires might be initially wary of him, especially with the Kyuubi's power, but his positive attitude could win them over. Tsukune, from Rosario Vampire, could learn a lot from Naruto about determination and fighting spirit.
One popular 'naruto rosario vampire crossover fanfiction' might be 'Naruto in the World of Rosario + Vampire'. It often has Naruto's unique abilities and character traits being introduced into the Rosario + Vampire universe, leading to interesting plot developments.
Begin with a prologue that sets up the situation. Maybe there are strange energy readings in both the Bleach world and the Rosario Vampire world that are somehow linked. Ichigo is sent to investigate in his world, and as he gets closer to the source, he is transported to the Rosario Vampire world. Once there, he is greeted by the chaos of the Yokai Academy. You can then start to introduce the different characters and their reactions to Ichigo's sudden appearance. This will slowly build the foundation for the rest of the story.
Maybe Naruto forms an alliance with some of the main characters in Rosario Vampire. He could use his ninja skills combined with his vampire abilities to fight against common enemies. Like, if there's a powerful dark force threatening both the vampire and human worlds, Naruto could be a key player in the defense.
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.
Another concept is that Godzilla somehow ends up in the Rosario Vampire universe. This causes chaos as the local creatures and humans are not used to such a huge and powerful being. The main characters from Rosario Vampire then have to figure out a way to either send Godzilla back to his own world or find a way for him to co - exist in theirs.
Well, he could fit in as a unique addition to the cast. His ninja abilities would be quite different from the normal powers in the Rosario Vampire world. He might be seen as a wildcard, with his speed and combat skills being a big advantage.