What are some interesting plot ideas for One Direction little sister fanfiction?

One idea could be that the boys reunite for a special charity concert. They each bring their own unique musical growth from their solo careers and blend it into a new sound for the concert. It could be a chance to heal old wounds and reignite their friendship on stage in front of their fans.

One idea could be that they are all babies in a magical nursery where the toys come to life and help them discover their musical talents. For example, a singing teddy bear could be their first music teacher.

One idea could be a little one in a magical world where they discover they have special powers. For example, they can communicate with animals and go on adventures with their new furry friends to save the enchanted forest from an evil sorcerer.

One idea could be the little sister getting involved in a mystery at school. Maybe she discovers a secret club and has to figure out what they're up to. Another could be her starting a new hobby like painting and the twins being really supportive but also a bit overprotective. Or she could have a talent for music and enter a local competition, with the twins helping her practice.

Maybe the little sister gets lost in the backyard which has been magically transformed by one of their inventions into a huge, mysterious maze. Phineas and Ferb then have to use their wits and knowledge of the backyard to find her. It could show their protective side towards their little sister.

One idea could be that Harry's little sister discovers she has a unique magical power that no one else in the family has. Maybe she can communicate with magical creatures in a way that even Hagrid is impressed by.

The little sister could start a club at school that is inspired by the things the brothers do. But she faces some challenges like getting enough members and dealing with a strict teacher. The brothers might try to interfere in their own clumsy way to help her out. It could also be interesting if she has a secret friendship with one of the brothers' rivals and has to keep it a secret from her family.

One idea could be the little sister developing a new power that none of the other Lab Rats have. This would cause a stir in the group as they figure out how to handle it.

One idea could be a fanfic where the main character gets to go on a world tour with One Direction. They experience all the backstage craziness, like pranks among the band members and impromptu jam sessions.

One idea could be that the members of One Direction are secretly wizards and they end up at Hogwarts. They could form a new club there, combining their muggle music with magic. For example, they use spells to make their instruments play on their own during a concert at Hogwarts.