If Naruto becomes a vampire in a harem scenario, he would likely be in a state of confusion at first. He has always been a ninja with a strong sense of justice. Now, with his vampire nature, he might struggle with the idea of feeding on others. The harem part would mean he has to manage relationships with multiple characters. Maybe some would be scared of his new form, while others would be intrigued and want to be closer to him.
Sakura might be shocked at first. She has always known Naruto as a regular ninja. But she could also be concerned and try to find a way to help him control his vampire side. Sasuke would probably be more cautious. He'd see Naruto as a potential threat, but also might be interested in how Naruto combines his ninja and vampire powers. Kakashi, on the other hand, would be calm and start observing Naruto to understand what has happened and how it affects the village.
One common theme is the power struggle. In both Naruto and Rosario Vampire, power is important. In the fanfiction, the main character often has to balance their power and use it to protect the members of the harem. For example, Naruto's ninja powers against the various supernatural threats in the Rosario Vampire world.
The Akatsuki could also be the main antagonists. Since they are after the bijuu, they would surely target Naruto once he has this special relationship with them. They might try more elaborate schemes to capture the bijuu from Naruto and his 'harem' of sorts.
In this fanfiction, Naruto could gain the ability to communicate with the bijuu on a deeper level. As a result, they start to see him as not just a jinchuriki but as a friend or even more. The plot could involve Naruto trying to protect the bijuu from threats while also dealing with the complex relationships that form within the 'harem' situation.
One possible scenario could be that Finn, after being turned into a vampire, struggles with his new identity. He might have to deal with the urge to drink blood while still holding onto his old values. For example, he could try to find alternative ways to satisfy his thirst that don't involve harming humans, like drinking animal blood.
One idea could be that Stiles is turned into a vampire against his will. Maybe he's attacked one night while out investigating something supernatural. As a vampire, he has to struggle with his new urges, like the thirst for blood, while still trying to be the same person his friends know. He might start to see the world in a different light, both literally and metaphorically, as his vampire senses heighten.
One possible story could be that Mimiko is bitten by a mysterious vampire one night while walking alone. She then starts to experience strange cravings and enhanced senses. At first, she's terrified, but as time goes on, she begins to embrace her new vampiric nature.
Well, Naruto's fighting style would incorporate a lot of his new vampire abilities. For instance, he could use his superhuman strength to break through defenses more easily. He might also develop new jutsus that are a combination of his ninja skills and vampire powers. Maybe he could create a 'blood mist' jutsu using his vampire - like ability to manipulate blood. And his stealth would be improved, allowing him to surprise his enemies more often.
One popular Naruto and Rosario Vampire harem fanfiction is 'Naruto in the World of Rosario Vampire'. It combines the unique elements of both universes, like Naruto's ninja skills in the supernatural setting of Rosario Vampire. The story often has interesting character interactions as Naruto navigates the complex relationships in the harem.