One idea could be exploring Yuki's past life before she was turned into a vampire. Maybe she had a family or a special talent that was lost in the transformation. Another could be a love triangle between Yuki, Zero, and Kaname in a different, more complex setting. For example, they are all part of a secret vampire society mission.
A great plot idea is if Yuki discovers a hidden power within herself that is not related to her vampire side. This power could be something that threatens the existing vampire - human balance. It could also involve Yuki having to choose between her loyalty to the vampires and her newfound power which might benefit the humans more.
Perhaps Takuma and Yuki are forced to go on a journey together to find a cure for a strange illness that is affecting the vampire population. Along the way, they face many challenges and their relationship deepens as they rely on each other. They might also encounter some old enemies who try to stop them from achieving their goal.
A plot could be Yuki and Kaname getting lost in a magical forest. In this forest, they discover secrets about their past that they never knew before. This could strengthen their relationship as they share these new revelations.
Well, perhaps in the fanfiction, there could be a ball in the vampire realm. Yuki is required to attend and Aido is tasked with being her escort. At first, Yuki is hesitant, but as the night progresses, they share a dance and a moment of connection. They then start to secretly meet up more often, exploring their new - found feelings for each other while trying to keep it from the other vampires.
Zero is an obvious choice. Their relationship in the original Vampire Knight was full of tension and unspoken feelings. In a fanfiction, they could explore their feelings more deeply and work together to fight against the darker forces in the vampire world.
One idea could be exploring Kaname's past further. Maybe a story where he meets an old acquaintance from before he became a vampire. This could bring out new aspects of his character, like his hidden fears or long - lost hopes.
Another plot could involve a time - travel scenario where Yuki goes back in time to before Zero became a vampire hunter. She tries to change the events that led to his current situation, but it gets complicated as it might affect the entire Vampire Knight world order. This could lead to a series of adventures where they have to face both old and new enemies.
One idea could be that Aido discovers a hidden power within Yuki that she's not aware of. He then helps her to master this power while they face opposition from the vampire council who fear her new - found strength. Another could be a time - travel plot where Aido and Yuki are sent back in time and have to navigate the old vampire society to get back to their own time.
One plot idea could be that Yuki and Aido are forced to team up to solve a mystery in the Vampire Knight world. Maybe there are strange disappearances among the vampires and they have to put aside their differences to figure it out. They start to respect each other's skills during the investigation.
One idea could be a prequel where young Yuki first discovers her unique connection to Kaname. Maybe she stumbles upon an old diary that has clues about their intertwined fates, and this sets off a series of events where she tries to learn more about Kaname's past while he is still a bit of an enigma to her.
Well, a plot could be centered around Zero's bites on Yuki having some unforeseen consequences. For instance, Yuki could start to develop some vampire - like powers slowly. This would cause a stir in the school, and Zero would feel guilty. Meanwhile, Yuki has to learn to control these new powers while dealing with the fact that she is becoming more like the creatures she once feared. And all this could lead to a more intense relationship between her and Zero as they face this new situation together.