One idea could be Riley and her friends from Girl Meets World somehow end up at Hogwarts through a magical portal. They could be sorted into different houses and have to navigate the challenges of Hogwarts life while also bringing their own unique personalities from Girl Meets World. For example, Riley's positive attitude might clash with some of the more traditional Hogwarts ways at first.
One idea could be a crossover where characters from both shows meet in a shared universe. For example, Cory and Topanga from 'Boy Meets World' could meet Riley and Maya from 'Girl Meets World' and they all go on an adventure together in New York City. They could help each other with their personal and relationship problems, sharing their different experiences from their respective shows.
Another plot could involve the Marauders getting involved in a mystery that is plaguing Hogwarts in the present day. They use their old - school pranking skills and knowledge of the castle's secrets to solve it. They might have to team up with some of the current Gryffindor students who remind them of themselves when they were young.
A plot could involve a group of Hogwarts students accidentally ending up at Ilvermorny and having to adapt to the new school's rules and culture while also trying to find their way back home. It would be a story of discovery and friendship as they interact with the Ilvermorny students.
One idea could be that Riley and Maya are now teachers at their old school. They have to deal with a new generation of students who are facing different but equally challenging problems. It would be interesting to see how they use their own experiences growing up to guide these kids.
One idea could be Lucas having a secret talent that he reveals during a school competition in the fanfiction world. For example, he might be an amazing singer but has been too shy to show it until a talent show episode.
One idea could be Ginger getting involved in a school project that goes awry but in the end teaches everyone a valuable lesson about teamwork. For example, she might be part of a group making a short film and they face issues like equipment failure and creative differences.
Some interesting fanfiction ideas could involve character growth. Maybe write about how a minor character from 'Boy Meets World' gets a chance to shine in 'Girl Meets World'. For instance, Minkus could have become a successful scientist and he comes to give a talk at the school in 'Girl Meets World'. Or you could focus on the friendships. Write about how the friendships in 'Boy Meets World' influenced the way friendships are formed in 'Girl Meets World'. Like how Cory, Shawn and Topanga's friendship was a model for Riley, Maya and Farkle.
Well, perhaps Maya starts to develop a crush on Lucas while he still has feelings for Riley. Maya feels guilty about it but can't help how she feels. Meanwhile, Riley is oblivious to Maya's feelings and keeps trying to push Lucas and Maya together as friends, which only complicates the situation more. This could lead to a lot of emotional turmoil and interesting character development.
Maybe a plot where Cory and Topanga take a trip down memory lane and revisit all the places that were significant in their relationship from 'Boy Meets World'. This could bring back old feelings and also allow them to share those stories with their children.
A plot could involve Josh and Maya working on a school project together. Since they have different perspectives, they initially clash but then gradually find common ground. As they spend more time together researching and preparing, they realize they have more in common than they thought and feelings start to develop.