Another plot could be that Casper and Wendy get into trouble when they accidentally break a major rule in the ghost world. They then have to find a way to fix it before the Ghost Council punishes them. They might seek the help of some of Casper's friendly uncles, who are more experienced in dealing with such situations.
Wendy, on the other hand, is a witch who has her own set of magical powers. She can use spells to do various things like fly on her broomstick or create potions. In the fanfiction, she brings her own unique personality and skills to the story, and her relationship with Casper is central to the plot as they interact and go on adventures together.
One idea could be that Casper has to learn about human emotions in a very short time. For example, he might experience love at first sight with a human girl and then struggle to understand jealousy when he sees her with another boy.
One idea could be a Casper crossover with Harry Potter. Casper could visit Hogwarts and cause some friendly chaos among the students and ghosts there. Maybe he'd befriend Nearly - Headless Nick and they'd have some misadventures together.
One plot idea could be that Stan and Wendy face the challenges of teen pregnancy together. They might struggle with telling their parents and friends, and deal with the changes in their school and social lives. For example, Wendy could be worried about her future academic prospects while Stan tries to find a part - time job to support their upcoming family.
A possible plot is that Wendy gets lost in a previously unexplored part of Neverland. Peter Pan and the Lost Boys go on a frantic search for her. While lost, Wendy discovers a hidden tribe of magical creatures that are shy and have been avoiding contact with the Lost Boys. Wendy befriends them and they help her find her way back. This could lead to a new alliance between the Lost Boys and these creatures.
A possible plot could be set in a parallel universe where Wendy is not a villain. She and Luigi meet at a grand Mushroom Kingdom festival. They both share a love for a particular type of mushroom - based food that is rare at the festival. As they search for this food together, they face various challenges like competing with other characters for the last piece, and through these shared experiences, they fall in love.
One idea could be that Casper befriends a lonely alien who has crash - landed on Earth. They team up to find a way to repair the alien's ship while also having adventures in the human world and teaching each other about their different cultures.
Well, a plot might involve Cartman and Wendy accidentally swapping personalities. This would lead to all kinds of chaos and hilarity in South Park. For example, Cartman - in Wendy's body - would have to deal with girl - related issues, and Wendy - in Cartman's body - would have to handle Cartman's friends. Or perhaps they find a mysterious object that gives them shared dreams, and they have to figure out what the dreams mean and how to stop a bad event from happening in those dreams.
One idea could be that Peter and Wendy discover a hidden island full of magical creatures that are neither fairy nor human. Another could be that they have to face a new villain who has the power to manipulate time, causing chaos in Neverland. Maybe Wendy tries to teach the Lost Boys some proper manners from her own world, which leads to humorous situations.
Maybe they accidentally get transported to a parallel world where the roles in Fairy Tail are all reversed. There, Wendy has to be the brave one leading Romeo through all the chaos to find a way back home. This could lead to a lot of character development and interesting interactions between them.