A more relationship - centered plot could be about two characters who are from rival vampire clans at the academy. They fall in love, but they have to keep it a secret because of the enmity between their clans. They then struggle to find a way to be together without causing a war within the academy.
One idea could be a crossover where characters from Vampire Academy and Twilight meet. For example, Rose Hathaway from Vampire Academy could encounter Bella Swan from Twilight. They could compare their different experiences with vampires and dhampirs. Another idea might be a 'what if' scenario. What if Lissa Dragomir from Vampire Academy was turned into a vampire instead of remaining a Moroi? In Twilight fanfiction, a cool idea could be exploring the backstory of the Volturi in more detail, like how they came to be so powerful.
One idea could be exploring the future of Rose and Dimitri's relationship in a more complex world. Maybe they face a new threat that tests their bond like never before.
Perhaps a story where the characters from Vampire Academy get transported to a different time or dimension. They have to adapt to the new environment while also trying to find a way back home, and in the process, they discover new things about their own powers and relationships.
One idea could be that Rose's pregnancy brings new challenges to her training at the Vampire Academy. Maybe she has to deal with physical limitations while still trying to prove herself. Another could be that her pregnancy causes a stir among the different vampire factions, some seeing it as a sign of hope and others as a threat.
One common plot idea is exploring their friendship in more depth. For example, a fanfiction might show how Rose and Lissa deal with a new threat to their bond, like a jealous classmate trying to drive them apart. Another idea could be a time - travel plot where they go back to a crucial moment in their past and try to change something that affected their relationship.
One idea could be exploring a different origin for the vampires in the Vampire Academy world. Maybe they were created as a result of a scientific experiment gone wrong instead of the traditional lore. This could lead to new power dynamics and conflicts among the characters.
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 character from Vampire Academy ending up in the Twilight world and having to adapt to their different vampire rules. For example, Rose could find herself in Forks and be really confused by the Cullens' 'vegetarian' vampire lifestyle.
A third plot idea could be that there is a new threat to the academy from an outside vampire group. Rose and Christian are among the few students who are aware of this. They secretly train together to prepare for the upcoming battle. During their training sessions, they learn more about each other's strengths and weaknesses, and a romantic relationship begins to blossom as they rely on each other for survival.
Perhaps in the fanfiction, Rose and Mason form an alliance with an unlikely group of vampires and dhampirs to fight against a new threat that is more powerful than any they've faced before. They have to learn to trust each other despite their differences.