One idea could be an OC who has the power of music in the Precure world. She could use melodies to heal or empower others. Another idea is an OC from a different dimension who comes to the Precure world with unique powers and has to learn how to fit in and fight alongside the Precure. Maybe an OC that is half - human, half - magical creature and has to hide her true identity while being a Precure.
An interesting Precure OC fanfic idea could be an OC who is a transfer student to the school where the Precure are. This OC has a secret past related to the villains and gradually discovers her own power to become a Precure. Also, an OC with the power of time manipulation in the Precure universe would be cool. She could freeze time to prevent disasters or rewind time to correct mistakes made during battles.
One idea could be creating an OC who has the power of music in the Precure world. They could use melodies to heal and fight against the villains. Another is an OC from a different dimension who stumbles into the Precure universe and has to learn their ways to help. And also, an OC that is a hybrid of a magical creature and a human in the Precure world, bringing unique powers and a fresh perspective to the story.
One popular idea is an alternate universe where the Precure characters have different powers or backstories. For example, they could be in a steampunk world. Another idea is a crossover with other popular magical girl series. This can bring new and interesting dynamics. Also, a fanfic about the Precure's daily lives outside of their heroic duties, like going to school or dealing with family, can be quite engaging.
A time - travel plot in a Precure All Stars fanfic could be really cool. Maybe the Precure travel back in time to the origin of their powers and have to make sure that the events that led to their powers being created happen correctly. It could involve meeting their predecessors and learning about the true nature of their powers.
One idea could be a crossover with another magical girl series like Sailor Moon. The Smile Precure girls could meet the Sailor Scouts and they team up to fight a common enemy that threatens both their worlds. Maybe they have to combine their powers in new and unexpected ways.
A great plot could be that the Precures lose their memories but still feel a strong urge to fight evil. They would have to figure out who they are and what their powers are while still protecting the world. Or, you could write a fanfiction where a new villain emerges who can control the stars in a different way than the previous ones. This would force the Precures to come up with new strategies to defeat the villain.
Another aspect is the changed relationships. The strong bonds between the Precure characters could be broken or distorted. Friends could turn into enemies, and the trust they once had could be completely shattered.
A hobbit OC fanfic could focus on a young hobbit who dreams of leaving the Shire to become a great warrior. They set out on a journey against the wishes of their family and face many challenges. Along the way, they meet different races like elves and dwarves and learn from them, all while trying to prove themselves in a world that doesn't expect much from hobbits in terms of combat.
One idea could be creating an OC that is a hybrid of different Pokemon types. For example, a Pokemon with the features of a water - type and an electric - type. This could lead to unique abilities and an interesting backstory about how it came to be. Another idea is to have an OC that is a trainer from a far - off, unexplored region. This trainer could have different training methods and a whole new set of Pokemon not commonly seen in the main Pokemon world. You could also make an OC that is a Pokemon with a special power related to emotions, like it can heal other Pokemon's wounds when they are sad or boost their power when they are happy.
An OC in a Grojband fanfic could be a time - traveler from the future. They come back to the present day where Grojband exists and tries to change the course of the band's history. Maybe they know that the band is going to face a big obstacle in the future and they want to prevent it. This OC could introduce futuristic music technology to Grojband, making their music even more extraordinary.
Well, in 'oc reincarnation fanfic', one interesting idea could be the transformation of the original character (oc). Maybe the oc is reincarnated into a completely different world with new abilities and challenges. For example, an oc who was a simple villager in their previous life might be reincarnated as a powerful mage in a magical realm. Another idea could be the exploration of past memories in the new life. The oc could have flashes of their former self and use that knowledge to their advantage in the new world.