Another plot could revolve around a forbidden romance between a vampire and a human that's different from the main story's romances. Maybe they have to keep their relationship a secret not just from the school authorities but also from a powerful vampire clan that has strict rules against such relationships. They would have to face many challenges and obstacles to be together.
A third idea is to create a story where the Day Class students start to suspect that there are vampires in the school. They form a secret group to investigate and this leads to a lot of tension between the Day and Night Classes. Some of the Day Class students might have ulterior motives for wanting to expose the vampires, like wanting power or revenge for something a vampire did in the past.
One idea could be a new student arriving at the Vampire Academy high school who has a mysterious power that no one has seen before. This could stir up a lot of curiosity and also some jealousy among the existing students.
One idea could be a new student who is a powerful witch arriving at the high school and getting caught in the middle of the vampire - werewolf feud. Another could be a time - travel plot where a character goes back to the early days of the high school when the original vampire drama began. Maybe a story about a human student who discovers a secret society within the high school that is dedicated to studying the vampires and trying to find a way to co - exist with them.
A more action - packed plot could be the red knight leading a rebellion against the vampire hierarchy. They gather other vampires and humans who are tired of the oppression and fight for a new order. Along the way, they discover secrets about the vampire world that could change everything.
A possible plot is that a dark force in both the Inuyasha universe (connected to Kagome) and the Vampire Knight world is trying to take over. Kagome and the main characters from Vampire Knight, like Zero and Kaname, have to work together. Kagome's knowledge of magic and spiritual energy could be combined with the vampires' powers to combat this threat. They might start off distrusting each other but gradually learn to rely on one another.
Well, a plot could revolve around Kanme's struggle with his vampire nature in a different way. For example, he discovers a new power within him that he doesn't understand and has to learn to control it while also dealing with the politics and power struggles in the vampire world. Also, a story where Kanme forms an unlikely alliance with a group of humans who are trying to understand vampires better could be really engaging.
Well, a plot could center around a time - travel aspect. Imagine if a character from the present in Vampire Knight Zero accidentally travels back to a crucial point in the vampire - human history. They could then change some events that have a ripple effect on the current story. Or, a fanfiction could be about a secret society within the vampire world that has been hidden from the main characters. This society could have its own rules and goals that conflict with what the protagonists believe. Additionally, a story about a curse that affects not only vampires but also humans in a unique way could be really engaging.
Maybe there's a Halloween prank gone wrong. A group of human students decides to play a spooky prank on the vampires, but they accidentally unleash an old vampire curse that starts to affect the whole academy. The characters then have to find a way to break the curse before it's too late.
One idea could be that Sasuke is a half - vampire who tries to hide his identity at high school. Sakura, being a curious girl, starts to suspect something strange about him. She could then discover his secret and they end up having to work together to protect the school from other more dangerous vampires.
One plot idea could be a new student, who is a vampire, arrives at Fairy Tail High School. They initially try to hide their true nature but end up getting involved in a school mystery that only their vampire abilities can help solve. Another could be a love story between a Fairy Tail student and a vampire student from another school during a joint event.
One idea could be a story where a new student arrives at Cross Academy who has a unique power that disrupts the balance between the vampires and the humans. This new character could be a hybrid of some sort, and their presence forces the main characters like Yuki and Zero to re - evaluate their beliefs and relationships.