Another plot could focus on a character who suddenly gains an unexpected Chara Force. This new power causes internal conflict as they struggle to control it. They might also face suspicion from their friends and foes alike, thinking it's a dangerous or untrustworthy power. They then have to prove that they can use it for good.
A more complex plot could involve a battle between different factions over the control of the Chara Forces. Each side believes they can use the forces to reshape Remnant in their own vision. The story could follow the different strategies and moral dilemmas of each faction as they fight, and how the main characters are caught in the middle.
Well, your OC could be from a different dimension and their fighting abilities are based on some strange energy not seen in the RWBY world before. They get caught up in a battle with a chara who initially sees them as a threat but later realizes they can be an ally. Maybe your OC's fighting chara has a special weapon or power that is linked to their emotions, and as they fight different characters in the fanfic, they learn to control their emotions better to enhance their fighting skills.
One idea could be exploring the backstories of the Guardian Characters in more depth. For example, how did they come to be and what were their experiences before they became Guardian Characters.
Ruby Rose is often a popular choice. Her silver eyes and leadership skills can be tied in interesting ways to the Chara Forces. For instance, her positive energy could be a catalyst for a certain type of Chara Force that is related to hope or protection.
One idea could be exploring a new character's journey in the RWBY world. Maybe a character from a different kingdom who has unique abilities and must team up with the main RWBY characters to face a new threat. Another plot could involve time travel, where a character goes back in time to change a crucial event in RWBY's history. A third idea is a story focused on the Grimm's origin and how to potentially find a way to permanently stop their creation.
Maybe in the RWBY Future Fanfic, the characters could explore new kingdoms. They might discover hidden secrets about the origin of Dust and how it can be harnessed in more powerful ways. This could lead to new power-ups for the characters and also introduce new allies and enemies.
A plot could revolve around a new threat that affects both universes. So, the RWBY characters and the Titanfall pilots have to team up. The RWBY characters' creativity in combat combined with the Titanfall pilots' skills in mech combat could make for an epic battle against the common enemy. There could be some cultural clashes and misunderstandings at first, but as they get to know each other, they become a formidable force.
One idea could be exploring an alternate universe where the characters' roles are reversed. For example, the villains are the heroes and vice versa. Another plot could involve a new Grimm threat that is unique to the Mirrorverse, forcing the RWBY characters to adapt their fighting styles. Or perhaps a story about a character getting lost in the Mirrorverse and having to find their way back while facing mirror versions of their friends and foes.
One plot idea could be that a character from RWBY gets transported to the world of Overlord. They might have to navigate the power - hungry and often dangerous world, trying to find a way back home while also dealing with the various powerful beings in Overlord. For example, Ruby could end up in the Tomb of Nazarick and have to figure out how to interact with the Floor Guardians without getting killed.
One idea could be exploring a different backstory for one of the main characters. For example, Ruby could have grown up in a more isolated part of Remnant and had to learn combat skills in a very different way. Another could be a time - travel plot where a character goes back in time to change a major event in the RWBY universe. Maybe they try to prevent the fall of Beacon earlier in the story, which would have a huge impact on all the characters and their relationships.
One idea could be a character getting a tattoo that has a hidden power. For example, a RWBY character might get a tattoo that glows when danger is near, like a warning sign. Another plot idea could be a story centered around a tattoo artist in the RWBY universe who creates unique tattoos for the Huntsmen and Huntresses, and each tattoo gives them a special ability or connection to the Dust energy. Maybe a tattoo that allows a character to communicate with Grimm in a strange way, adding an interesting twist to the story.