One idea could be a story where Aidou and Yuuki go on a secret mission together. They might face an ancient vampire threat that requires their combined skills to overcome. Another plot could involve Yuuki having a vision about Aidou's past, and she tries to help him come to terms with it.
Well, a great plot could be that Aidou discovers a new power within himself, but he's afraid to use it. Yuuki, being the understanding and brave character she is, encourages him to embrace it. As they practice together, they grow closer and their relationship deepens. This could lead to a situation where they have to use this new power to save their vampire and human friends from a powerful enemy.
A really interesting plot might be a time - travel fanfiction. Yuuki somehow gets sent back in time to when Aidou was a young vampire just starting to learn about his powers. She helps him navigate the difficult vampire society at that time, and in the process, they form a bond that is different from their relationship in the present. This changes the course of events in the present as well, making for a complex and engaging story.
One idea could be a fanfiction where the kiss is a turning point in their relationship. After the kiss, Zero struggles with his vampire nature more intensely as his feelings for Yuuki deepen. Yuuki, on the other hand, realizes she has a stronger connection to Zero than she thought. Another plot could be that the kiss was part of a deal to save the school from a new vampire threat. They have to pretend to be in love after the kiss, but then real feelings start to develop.
One unique way to develop their relationship is through a cooking adventure. Suppose they both end up in a situation where they have to cook for a big event in the vampire world. Yuuki has some human cooking knowledge and Aidou has some vampire - specific ingredients and techniques. As they combine their skills, they learn more about each other's cultures and grow closer. They might start off bickering but end up having a great time and realizing how much they enjoy each other's company.
Well, one plot could be that Yuuki has a premonition of Kaname's death. She then tries everything in her power to change the future. This could involve her making deals with other powerful vampires or delving into ancient vampire magic. Their relationship would be put under great strain as she battles against time to save him.
Another interesting plot twist could be a time - travel scenario. What if Yuuki was sent back in time to before Zero became a vampire? She could try to prevent his transformation, which would change the entire course of their relationship. This would also bring up questions about whether she should interfere with fate and how it would affect the future of the vampire - human world.
One great fanfiction could be about Kaname and Yuuki's secret meetings in the moonlight. They might share their deepest fears and desires away from the prying eyes of the vampire and human worlds. In this fanfic, their love could be portrayed as a powerful force that overcomes all the obstacles in their path, like the animosity between vampires and humans.
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.