One interesting storyline could be about Magical Sempai's origin. Maybe she wasn't always magical but gained her powers through a strange encounter. Another could be a love story where a character falls in love with Magical Sempai despite her often - clumsy magic. And there might be a story where Magical Sempai has to save the school from a dark magic threat using her unique brand of magic.
Well, in some fanfiction, there could be a storyline where Magical Sempai loses her magic for a while. This would lead to her having to rely on her friends and normal human skills to get by. It could also show her learning more about herself and her relationships without her magic. Another storyline might involve Magical Sempai traveling to a different dimension where her magic works differently, and she has to adapt quickly. Also, a story could focus on Magical Sempai teaching someone else how to use magic in her own wacky way.
Obviously, Magical Sempai herself is very popular. Her clumsy yet endearing use of magic makes her a central figure. The main character who often interacts with her, like her junior, is also quite popular. He is the one who witnesses all of her magical mishaps and often has to clean up the mess. And sometimes, the school principal who has to deal with the chaos caused by Magical Sempai's magic also appears in many fanfictions and is a well - liked character.
There could also be a fanfiction where the magical animals start to rebel against the wizards. Maybe they feel exploited or mistreated. This would lead to a big conflict in the wizarding world. The wizards would have to find a way to make peace with the animals. Some wizards might side with the animals, creating a divide within the wizarding community. It would be a really exciting and different take on the Harry Potter and magical animals concept.
One interesting storyline could be about creating a new magical block that has the power to transport wizards to different eras in the wizarding world. For example, it might take them back to the time of the founders of Hogwarts, allowing them to witness the creation of the school and learn ancient magic that has been lost over time.
One interesting storyline could be about a new and rare magical creature being discovered in the Magical Menagerie. The main character, perhaps a young wizard or witch, tries to protect this creature from dark wizards who want to use it for evil purposes.
Another could be a 'what if' scenario. Like what if a certain character got injured along the way and how it would change the dynamics of the group. This could involve exploring the relationships between the characters as they deal with the unexpected situation.
One interesting storyline could be about the characters' exploration of a new, mysterious part of the Hollows. They might encounter strange creatures and have to use their unique abilities to survive.
There are fanfictions where the Warehouse 13 agents go on a mission to recover an artifact that has been lost for centuries. This artifact could hold the key to saving the world from a great danger. Another type of storyline could be about a character from the Warehouse getting trapped in an artifact - like a mirror where they are stuck in a different dimension. And then the other agents have to find a way to get them out. There are also fanfictions that deal with the internal politics of the Warehouse, with different factions vying for control over the artifacts.
One interesting storyline could be a different take on the relationship between Klaus and Caroline. Maybe in the fanfiction, they team up to face a new and powerful enemy that neither of them could defeat alone. This would bring out new sides of their characters as they learn to trust and rely on each other more.
One interesting storyline could be the exploration of alternate universes within the Underverse setting. Characters might discover new powers or forms in these different realms.
One interesting storyline could be a reimagining of Batman's first encounter with the Joker in the 1939 fanfiction context. Maybe the Joker starts as a small - time criminal and Batman has to figure out his true motives early on.