You could also write a story about a time - traveling event in the magical school. A group of students accidentally travel back in time to the founding days of the school. They have to navigate the old rules and ways of the school while also trying not to change the past too much. If they do, it could have disastrous effects on the present day of the school.
For a Goosebumps fan fiction, how about a story where a family moves into a house that was once the inspiration for a Goosebumps story. The family starts experiencing all the spooky events from the story. The youngest child in the family, however, has a special ability to communicate with the spirits causing the trouble. They use this ability to try and make peace with the spirits. Another idea is a story set in a Goosebumps - like amusement park. The rides are all based on the scariest parts of the Goosebumps series. A group of friends gets trapped in the park overnight and has to survive the terrifying attractions. Also, a story about a Goosebumps author who gets sucked into his own stories and has to find a way to write himself out of them.
A simple idea is to focus on a group of survivors who are trying to find a rumored safe haven. Along the way, they face various challenges like mutant creatures and gangs of raiders. One of the main characters could have a special skill, like being able to communicate with animals, which helps the group in their journey.
One idea could be a story where Senbonzakura and Sode no Shirayuki are forced to fight side by side against a common enemy they would never normally ally with. Maybe a powerful dark force has emerged that threatens their respective owners or the world they exist in. This would put them in a situation where they have to overcome their differences and work together, leading to an interesting dynamic as they learn about each other's powers and abilities.
Well, you could write a fan fic where the relationships between the characters are reversed. So if in the original there are certain rivalries, in the fan fic they become allies and vice versa. Also, a story about a character who loses their power but discovers a new way to be strong within the 'unordinary' world would be interesting. Or how about a fan fic that takes place in a parallel dimension within the 'unordinary' universe where the rules of powers are slightly different?
You could create a story where a new superhero emerges from an ordinary background, like a shy librarian who discovers she has the power to control time. Maybe she uses her power to stop a series of library robberies at first, but then realizes she has to face a much bigger threat that endangers the whole city.
Some interesting ideas for Riverdale fan fiction could be a crossover with another popular teen drama. Imagine the characters of Riverdale meeting the characters from 'Stranger Things'. It would be really cool to see how they interact. You could also write a fan fiction that focuses on the future of Riverdale. What will happen to the town and its residents ten years from now? Will Archie still be in town? How will Veronica's business empire develop?
You could write a fan fiction about a Pokemon trainer who has the unique ability to communicate with Pokemon on a deeper level than others. This trainer goes on a journey to solve the mystery of why some Pokemon are becoming more aggressive. Along the way, they meet different Pokemon species and form strong bonds with them. They might discover that there is an unseen force affecting the Pokemon's behavior, like a new type of pollution or an ancient curse.
One idea could be to write a fan fiction where Bluey and her family go on an adventure to a magical land. They could meet new characters and have to solve puzzles to get back home.
One idea could be that Sonic accidentally runs into the world where Wonder Girl exists. He's confused at first but then realizes he can use his speed to help her in a battle against some powerful villains. Maybe he could use his speed to create distractions while Wonder Girl delivers her powerful blows.