Another interesting plot could involve Female Neptune being from a different dimension and having to adjust to the world of RWBY. She could bring her own set of values and skills from her home dimension, which could cause some clashes and also some great character development moments within the team.
One great Neptune RWBY fanfic could be 'Neptune's Adventure in Vale'. It might explore his character in more depth as he navigates the challenges in Vale. Another could be 'Neptune and Team RWBY's Team - Up' where he teams with the girls on an exciting mission. There's also 'Neptune's Hidden Talents' which could uncover some unexpected abilities of his.
One idea could be that Ruby is brainwashed by an enemy to turn against her team. Then her friends have to find a way to break the brainwashing and bring her back. This could involve a lot of emotional scenes and intense battles.
Perhaps a fanfiction where a Solarballs character has a long - lost relative on Neptune. They go on a journey to Neptune to find this relative and end up uncovering secrets about the planet and their own family history. Along the way, they form alliances with other beings on Neptune who help them in their quest.
You could write about the Son of Neptune getting lost in a mysterious realm. In this realm, the rules of his world don't apply. He has to learn new ways to survive and fight. Along the way, he meets a group of misfits who he has to team up with. Together, they try to find a way back home while also uncovering secrets about this strange place that could have implications for his own world.
There might be a fanfiction that focuses on the friendship between Sun and Neptune and how it evolves over time. For example, it could show how they support each other through difficult times at school, like when facing tough exams or dealing with mean classmates. In this type of fanfiction, their bond grows stronger as they share their insecurities and dreams.
Well, a great plot for Percy son of Neptune fanfiction could involve Percy getting lost in a time - warp within the ocean. He could end up in an era where Neptune was just starting to gain his powers. This would force Percy to interact with a younger version of his father and also deal with the different rules and threats that existed back then. Additionally, Percy could find a way to bring some knowledge from that time to his present to help in a current conflict. Also, Percy might have to team up with some primitive sea creatures who have their own unique abilities and motives.
One idea could be female Yugi becoming a powerful duelist and competing in international dueling tournaments. She could face off against opponents from different cultures and use unique strategies.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of RWBY fanfics, and you're likely to find many that feature Neptune. Another place is FanFiction.net. It also has a wide range of RWBY - related fan works, including those centered around Neptune.
One interesting storyline could be Neptune and Weiss going on a mission together. They might start off bickering as they have different personalities, but as the mission progresses, they learn to rely on each other's strengths. Neptune's laid - back nature could balance out Weiss's more uptight attitude. Another could be a story where Neptune gets injured and Weiss has to take care of him, leading to a deeper emotional connection between them. And there could also be a fanfiction where they both discover a new type of Grimm and have to figure out how to defeat it together, during which their relationship blossoms.
One plot idea could be Percy discovers some hidden prophecy while reading 'Son of Neptune' that affects his future adventures. Another could be that he reads it and starts to question his own role in the demigod world more deeply.