Perhaps a fanfiction plot could revolve around a new threat to Mars that neither the Martians nor the Earthlings have faced before. The princess and the Earth hero must combine their knowledge and skills to defeat this threat. It could be a mysterious disease that is spreading across Mars, or a new alien race that has arrived with unknown intentions. They would need to journey to different parts of Mars, seek help from various tribes, and in the process, their relationship could develop in new and interesting ways.
One idea could be exploring a different backstory for the princess. Maybe she has a secret power that she's been hiding from everyone. Another could be a story where the main character from Earth forms an unexpected alliance with a group of Martian outcasts in order to rescue the princess.
A great plot could involve time travel within the 'A Princess of Mars' universe. The hero goes back in time and changes a crucial event that has a huge impact on the relationship between Earth and Mars. This could lead to a whole new set of adventures and challenges for the characters. Also, a plot where the princess has to take on a male disguise to escape a dangerous situation and in the process, she discovers new things about her own identity and the society she lives in.
Perhaps Naruto gets lost in a parallel dimension where he meets Sailor Mars. At first, they don't understand each other but as they face challenges together, like fighting off strange creatures in that dimension, they start to learn from one another and develop a bond. Their different fighting styles could lead to some really cool battle scenes in the fanfiction.
One plot idea could be that Jadeite is actually a double agent and teams up with Sailor Mars to take down a common enemy. They start off as adversaries but as they work together, they begin to understand each other's motives.
Another plot could be that Veronica is on a trip outside of Neptune and accidentally meets someone from her past that she had a crush on when she was younger. They reconnect and start to fall in love all over again, but there are obstacles in the form of long - distance and the secrets they both carry from their pasts.
One idea could be that Harry discovers his 'son of Mars' heritage gives him unique combat abilities in the wizarding world, like super - fast reflexes and enhanced dueling skills.
A story could revolve around a conflict within their own organization. Mars and Saturn find themselves on opposite sides of an internal power struggle. They have to decide whether to stay loyal to the organization or follow their own moral compasses. This would involve a lot of political intrigue within the Pokemon - related group they belong to, with battles not just against Pokemon but also against other members of their group.
Well, an interesting plot could be that an OC is a shape - shifter. At first, the Biker Mice are suspicious of this OC. But as the story progresses, they find out that the OC is actually an ancient being who can help them defeat a powerful new enemy. Maybe the OC has the power to manipulate time and uses this ability to prevent a major disaster on Mars. Or there could be an OC who is a musical prodigy on Mars and uses their music to soothe the savage beasts that the villains often use in their attacks, thus helping the Biker Mice in a unique way.
Maybe in the fanfiction, Mia goes on a diplomatic mission to a neighboring country. During this mission, she meets a young prince or princess who becomes her close friend and they work together to solve a big problem between their two kingdoms, like an environmental issue or a trade dispute. This would show Mia's growth as a princess in a new and different setting.
One idea could be to explore what would happen if Sara Crewe had a secret magical ability that she discovered while in the attic. For example, she could be able to communicate with the mice in a more profound way and they help her find a hidden treasure in the old house.
One idea could be exploring the backstory of the psychic powers in more detail. For example, how did the main character first discover her powers? Another could be a time - travel plot where the princess goes back in time to change an event that had a major impact on her kingdom. Maybe she tries to prevent a war or save a loved one from an early death.
One plot idea could be that Kagome is transported to the world of Princess Princess. She could be mistaken for a new student in the all - male school and have to navigate the strange rules and hierarchies there. Maybe she uses her miko powers to help solve some problems in the school that are related to an ancient curse.