An interesting Precure OC fanfiction idea could be an OC who is an outcast in the Precure world at first. Maybe they don't have the typical 'cute' appearance of a Precure but possess extremely powerful magic. They struggle to be accepted by the other Precures but eventually prove their worth. Another idea is an OC who is a detective - like Precure. This OC could use their intelligence and deductive skills to figure out the plans of the villains. And a third idea could be an OC who has the power of transformation not just in appearance but also in personality, depending on the situation they are in 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 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.
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.
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 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 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.
Well, you could have an OC that is a skilled hacker who gets involved with the Phantom Thieves by accident. They might have a Persona that represents a famous code - breaker from history. Also, an OC who is a foreign exchange student from a country with a very different cultural background could bring in new elements to the fanfiction. Their Persona could be influenced by their home country's folklore. Maybe an OC who is a prodigy artist and uses their art skills to create powerful items in the Metaverse, with a Persona related to a great artist from the past.
You could have an OC that is a young witch who idolizes Bayonetta. She tries to copy Bayonetta's style and fighting techniques but often fails in a comical way at first. As the story progresses, she discovers her own unique way of being a witch. Or an OC who is a cursed object collector. This OC comes across Bayonetta when investigating a powerful cursed object and they end up working together to either destroy or control the object's power.
One idea could be an OC who is a spy sent to infiltrate Doflamingo's organization. This OC could have a hidden past that slowly gets revealed as they gain Doflamingo's trust. Another idea is an OC with a special power that Doflamingo wants to control or use for his own evil plans. For example, the OC might be able to manipulate time in a small area, which could be a great asset in battles or heists.
One idea could be to create an OC who is a new dancer in town. This OC could bring a different style of dancing to Footloose's world, like a fusion of modern and traditional dance. They could face challenges in getting the town to accept this new form of expression.
A great concept for superhero oc fanfiction is a hero who has the power of empathy. They can sense the emotions of others and use that to either calm down villains or boost the morale of their fellow superheroes. Also, you could write about a superhero oc from another dimension who comes to our world with powers that are completely alien to our understanding, like the ability to turn into a living energy form.