What are some interesting ideas for a Billy and Mandy Brains fanfic?

Perhaps they could be in a modern - day high school setting where Mandy is the cool, mysterious girl and Billy is the nerdy but kind - hearted boy. They get paired for a school project and at first they clash because of their different personalities. But as they spend more time together, they find common interests like a love for old horror movies and start to develop feelings for each other.

Perhaps in a fanfiction where there's an alternate universe. In this universe, Billy and Mandy are normal kids without all the spooky stuff around them. They participate in a school play where they have to kiss as part of the script, and this kiss makes them see each other in a different light, starting a romantic sub - plot in this otherwise normal world for them.

First, you should think about the relationship between Billy, Mandy and Brains. Decide if you want to focus on their friendship, rivalry or something else. For example, you could start with a situation like Billy accidentally breaking one of Brains' inventions that was important to Mandy.

A possible plot for Billy and Mandy crossover fanfiction is that they end up in a world of magic school. Billy is completely clueless about magic at first and keeps causing chaos in the classes. Mandy, on the other hand, is intrigued by the different types of magic and tries to learn as much as she can. They get involved in a competition between different houses in the school, and their friendship is tested as they face various challenges and temptations during the competition.

One idea could be that they discover they are going to be parents unexpectedly and have to deal with the reactions of their friends and family. It could be a comical situation as they are both rather unconventional characters. For example, Grim might be shocked and initially try to find a way to reverse it, but then slowly warm up to the idea of being an 'uncle' of sorts.

A possible plot is that the kiss was part of a bet. Billy lost a bet to Grim and as a result had to kiss Mandy. But then, unexpectedly, Mandy didn't mind as much as she thought she would and it led to a series of comical and heart - warming events in their little group.

One idea could be to explore what would happen if Grim lost his powers for a while. Billy and Mandy would have to figure out how to deal with the supernatural chaos without Grim's direct help. Another could be a time - travel plot where they go back to when Grim first became the Grim Reaper and try to change some of the rules of the underworld. Maybe they could also meet some of Grim's old friends or enemies from his past that would add a new layer of adventure.

One popular 'billy and mandy fanfic' could be 'The Adventures of Billy and Mandy in the Enchanted Forest'. It takes the characters on a journey full of magic and mystery. Another one might be 'Billy and Mandy's Friendship Test' which explores their unique relationship in different situations.

There might be a fan fiction where Billy and Mandy swap personalities. Billy becomes all serious and Mandy turns into a goofy, carefree character. This could lead to a lot of humorous situations as they try to adjust to their new selves and still deal with the underworld tasks they often face.

One idea could be that the Reaper loses his scythe and Billy and Mandy have to help him find it in the Underworld. They encounter various strange creatures along the way.