Well, perhaps Erica's sister could form an unlikely alliance with one of the main characters. For example, she teams up with the babysitter to protect their town from a new threat that is more powerful than the regular vampires they've dealt with before. She might bring in a fresh perspective and unique skills to the team.
Obviously, Erica's sister is a main character. And we can expect characters from the original 'My Babysitter's a Vampire' series to be involved as well, like the babysitter who is often in the middle of the vampire - related chaos. There may also be other vampires and humans who interact with Erica's sister throughout the story.
One common theme is her relationship with the vampires. Since the show is about vampires, many fanfictions explore how Rory's sister interacts with them, whether it's friendship, fear, or something more complex.
One idea could be that the vampire babysitter has to protect the kids from an ancient vampire hunter who mistakes the babysitter for a rogue vampire. Another could be that the kids discover a secret power within themselves that helps the babysitter in her vampire - related troubles. Maybe the babysitter has to attend a vampire council meeting and the kids accidentally tag along and cause chaos.
Another interesting idea is to focus on the relationship between the babysitter and the kids they are taking care of. What if one of the kids finds out about the vampire nature in a really cute or funny way? It could lead to some heartwarming and humorous moments in the fanfiction, like the kid trying to keep it a secret while also being super curious.
One interesting aspect could be the unique character dynamics. In yaoi fanfiction based on 'My Babysitter's a Vampire', the male characters might be portrayed in different relationships than in the original show. For example, their interactions could be more intimate and full of unspoken emotions.
One idea could be an OC who is a new vampire in town and befriends the babysitter vampire. They could team up to protect the neighborhood from a new threat, like a group of werewolves.
Maybe the vampire's pregnancy is the result of a unique vampire ritual. The babysitter has to figure out how to raise a half - vampire baby in a human world. She could start to teach the kids she babysits some vampire - friendly things to prepare them for the new addition.
Another idea is that the characters from 'My Babysitter's a Vampire' are brought to the Naruto world. They are shocked by the existence of ninjas and the different kind of powers. The babysitter, who is a vampire, could use her vampiric abilities to help Naruto in a battle against a powerful enemy, while Naruto helps her adapt to this new and strange world.
One great piece of fanfiction could be 'The Adventures of Rory's Sister'. It really delves into the character of Rory's sister in unique ways, exploring her relationships within the My Babysitter's a Vampire world. It might be available on some popular fanfiction websites.
The addition of an original character (OC) to the existing 'My Babysitter's a Vampire' universe makes it interesting. It allows for new relationships to be explored, especially involving Benny. For example, the OC could be a new type of supernatural being that Benny has to figure out how to interact with.