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 that the Titans from Titanfall end up in the world of RWBY. They could team up with the Huntsmen and Huntresses to fight a new, powerful Grimm threat that is too much for either side to handle alone. The Pilots could share their advanced combat skills with the RWBY characters, and in return, the RWBY characters could teach the Pilots about the use of Aura and Semblances.
Another interesting concept is that some of the Titans could be modeled after the RWBY characters' weapons or fighting styles. For instance, a Titan with a scythe - like weapon similar to Ruby's Crescent Rose, and it could have a special ability based on her speed and agility.
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.
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.
One idea could be exploring new Grimm species in the RWBY GP fanfic world. Maybe there are Grimm that can blend into the environment in a more advanced way, like turning into man - made structures to ambush Huntsmen and Huntresses. Another plot could revolve around a new character who has a unique weapon design that combines different Dust types in an unorthodox way, and they have to prove themselves in the academy.
One idea could be the young RWBY characters having a mini adventure in the woods near their homes. They might discover a strange creature and try to befriend it. Another could be them having a pretend battle tournament in their backyard, with each using their unique abilities in a more innocent and unrefined way.