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.
Create a unique and engaging plot. Don't just have the villains win easily. There should be a complex sequence of events that leads to the bad end. Maybe introduce a new, more powerful villain or a moral dilemma that the Precure can't overcome.
A fanfic of Star Twinkle Precure can be a creative exploration of the universe. It might focus on the characters' relationships in more depth. For example, it could expand on the friendship between the Precure girls, showing their daily interactions outside of battles.
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.
First, decide which Precure characters you want to feature. Then, think about the plot. It could be something simple like a day in the life of the Precure, or a more complex adventure. Next, create an outline of the story, including the beginning, middle, and end. After that, start writing the first draft. Don't worry too much about grammar or spelling at this stage.
One possible scenario could be that the Maho Girls Precure are on a mission when they encounter a powerful magic that starts to transform them into origamis. As they transform, they gain new powers related to the properties of origami, like being able to fold and unfold themselves to dodge attacks or create origami - based weapons. They then use these new abilities to defeat the evil that threatened them.
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.
One common theme is friendship. The Precure series is known for strong friendships, and fanfics often delve deeper into how these friendships develop and are maintained.
To start writing a Precure OC fanfic, begin by brainstorming your OC's powers. If they have the power of light, consider how that power will be used in battles and how it might affect their relationships with the other Precure. After that, establish the setting. Is it in the same town as the original Precure? Or a new location? Then, write a rough outline of the story, including the introduction of your OC, the conflict they will face, and how they will resolve it.
Cure Black is also a very popular character. She's one of the original Precure characters and has a strong, determined personality. Fans like to explore her backstory more in fanfic and also see her interact with the newer Precure characters.