Another idea is that an ancient vampire lord from a different dimension arrives in the Naruto world. He's extremely powerful and starts to turn some of the ninjas into his vampire minions. Naruto and his friends have to find a way to stop him. They might have to travel to the vampire's home dimension to find a weakness. This would involve a lot of exploration and discovery, both in terms of the new dimension and the vampire's powers.
One idea could be that Loki gets turned into a vampire while in the midst of his schemes against the Avengers. This new state gives him different powers and motives. He might struggle with his newfound thirst and also use his vampire abilities to outwit the Avengers in different ways.
In a 'naruto king of vampires fanfiction', it could be that the author has created a unique crossover concept. Naruto, who is known for his ninja skills in the original series, might now be in a world where vampire rules apply. He could be the king of vampires, which means he has to rule over a vampire clan or community within the Naruto - like setting. This could lead to all sorts of plotlines, such as political intrigue among vampires, Naruto trying to maintain peace between vampires and regular ninja, or even using his vampire powers to protect his village in a different way than he did as a normal ninja.
You could make Rainbow Dash a vampire with the ability to fly at super - sonic speeds even for a vampire. She might struggle with her new blood - lust while still trying to be loyal to her friends. Maybe she has to compete in vampire - only races in the night sky.
One idea could be a crossover where a vampire from the Harry Potter universe somehow ends up in the world of Tokyo Ghoul. Maybe a vampire who was hiding in the Forbidden Forest gets transported to Tokyo and has to adapt to the new rules of the Tokyo Ghoul world, dealing with ghouls and the CCG. This could lead to some interesting power dynamics as the vampire's magic might be a new factor in the Tokyo Ghoul ecosystem.
A great plot for 'Dance of the Vampires Fanfiction' could be set in a small town that has a long - forgotten vampire history. The local library has a hidden book about the 'Dance of the Vampires' which a curious teenager discovers. As she delves deeper into the mystery, she starts to see vampires around town. One of them, an older and more powerful vampire, takes an interest in her. He uses the dance as a way to draw her in, and she has to figure out how to escape his clutches while also uncovering the town's secrets.
One idea could be that the vampires, being from an ancient and noble line, teach her unique forms of magic that are different from what she would learn at Hogwarts. For example, they might teach her how to use her magic in a more instinctual and primal way. In this fanfiction, the female Harry Potter could also have enhanced senses due to being raised by vampires, which would give her an edge in her magical adventures.
Since it's a fanfiction, there could be many interesting characters. Naruto as the king of vampires is surely an interesting take. There might also be new vampire characters created specifically for this story that interact with Naruto in unique ways.
One idea could be Lincoln using his physical strength while shirtless to fend off the vampires in a more primal way. Maybe he has some special mark on his bare chest that gives him an advantage against the vampires.
A love story could be at the center. A demigod falls in love with a vampire, which is completely against the rules of both their species. They have to overcome not only the disapproval of their own kind but also find a way to deal with their differences in power, lifespan, and the fact that the vampire needs blood while the demigod has a different diet. This could lead to a very passionate and complex relationship filled with many obstacles.
One idea could be a new student arriving at the school who has a special power that no one has seen before. This could cause a stir among the vampire students and teachers. Maybe they are able to control the shadows, which is a very rare ability even among vampires.