One idea could be exploring the backstories of the sisters more in - depth. Maybe each sister has a secret talent or a past trauma that hasn't been fully revealed in the original show. Another idea is to create an alternate universe where the sisters have different occupations but still maintain their strong bond. For example, one could be a famous artist, another a scientist, and they have to deal with the challenges of their new lives while still being there for each other.
You could write a fanfic where the 'bad sisters' get involved in a mystery. Maybe there's a strange occurrence in their neighborhood and they decide to investigate. As they dig deeper, they discover secrets about their own family and the people around them. This would add an element of suspense and mystery to the fanfic. They could use their unique personalities and skills to solve the mystery, and in the process, learn more about themselves and each other.
Some fanfic ideas might include a story where one of the siblings gets into trouble and the others have to come to their rescue. It could be legal trouble, like being wrongly accused of something. Or it could be about a relationship problem that one is having, and the siblings use their own experiences and wisdom to help them through it.
One idea could be that the Bowsette sisters go on an adventure to find a magical artifact that can save their kingdom from a dark force. They face various challenges along the way, like tricky puzzles and powerful enemies.
One idea could be to explore a scenario where friends turn on each other due to a misunderstanding over a valuable heirloom. Maybe one friend was entrusted with it for safekeeping but lost it, and the others think it was stolen on purpose.
Another plot idea could be a what - if scenario. For example, what if one of the sisters had a different power? This could change the whole dynamic between them and the story. Say, if Elsa had the power to control time instead of ice. It would lead to different challenges and interactions with Anna, like having to deal with the consequences of changing time to save someone, but also the potential chaos it could cause in Arendelle.
One idea could be to explore Ron's bad boy side in a different dimension where he's part of a secret rebel group against an evil force. He could have a cool new look, like leather jackets and spiky hair.
Another plot could be the bad gal trying to reform but her past keeps coming back to haunt her. Her old allies turn on her because they don't trust her new good - girl act, and she has to prove herself while also dealing with her inner demons.
One idea could be a fanfiction where the Grimm sisters travel to a modern city and have to deal with magic that has been corrupted by technology. Another could be a story where they meet their ancestors and learn new magic from them. Maybe a fanfiction where they get trapped in a fairy - tale world that has been twisted in a really strange way.
A plot idea could be that the Sisters Grimm discover a hidden realm within their own world that has all the forgotten or lost fairy - tales. They then have to figure out how this realm is connected to the problems in their own town. Also, a story where they swap powers or abilities for a day and have to deal with the chaos that ensues. For example, if Sabrina has Daphne's ability to see the good in people and Daphne has Sabrina's more cynical view, it would lead to some interesting character development.
A plot about the sisters getting superpowers could be really exciting. They could start off not knowing how to control their powers and have some comical and also dangerous situations as a result. For example, one sister might accidentally set off her power in public and they have to figure out how to cover it up while also learning to use it properly.
Another idea is that Jesse and Amy go on a road trip. Along the way, they meet different people and have adventures. Maybe they encounter a group of musicians and end up joining them for a concert, which is something they've always wanted to do but never had the chance. This could strengthen their bond as friends and also help them discover new things about themselves.