A more emotional plot could be that they discover they have a shared past that they were unaware of. Maybe they both had a connection to a certain character who was important in their lives before they became who they are now. This revelation makes them question their own paths and they start to see each other in a new light, leading to a tentative alliance and exploration of their similarities and differences.
One idea could be Cinder being transported to an alternate universe within the RWBY world where the roles are reversed. For example, she could find herself in a world where she is a huntress in training, facing the same challenges as the main characters but from a different perspective. Another plot could involve a team - up between Cinder and a group of RWBY characters against a common, greater enemy that threatens both their goals and the world. Maybe a new, powerful Grimm that has abilities they've never seen before.
A plot could be Raven discovers a hidden power within the Bandit Tribe that could change the balance of power in Remnant. She has to decide whether to use it for the tribe's gain or keep it a secret to prevent others from misusing it.
The OC could be a lost traveler who stumbles upon Raven's hideout. Raven at first is cautious but then decides to help the OC find their way back home. Along the way, they encounter various obstacles like a group of bandits or a magical storm. As they face these challenges, they develop a bond. Another plot is that the OC is a healer who comes to a place full of injured people. Raven is one of the wounded and the OC's gentle and kind nature makes Raven open up in a way she hasn't before. However, there is a group that wants to stop the OC from healing people for their own evil purposes, so Raven and the OC have to fight back.
One idea could be a fanfic where Cinder forms an unexpected alliance with a Beowulf. Maybe she's on a mission alone and gets surrounded by enemies, and a Beowulf, which is usually a foe, decides to help her for its own mysterious reasons. This could lead to a whole new power dynamic and a strange friendship or partnership.
One interesting concept could be the exploration of their opposing natures. Ruby is often seen as pure - hearted and full of hope, while Cinder is more devious and power - hungry. In fanfiction, this contrast can lead to some intense character - driven stories where they either learn from each other or clash in more complex ways than in the original series.
One idea could be that Cinder realizes the true cost of her actions after seeing the destruction she has caused on a personal level. For example, she might encounter a family that has been torn apart because of the events she set in motion. This could be the start of her journey towards redemption.
Another plot could be that there's a threat to both Raven and Starfire's families. They have to work together, with their families' support, to defeat this threat. It could be an evil entity that targets both Earth and Starfire's home planet. Through this adventure, their families learn to trust and rely on each other, and Raven and Starfire's friendship deepens into something more like family on a deeper level.
One plot idea could be that Raven and her sister have to team up against a powerful dark force that threatens their world. They start off with a rocky relationship due to past differences but as they fight together, they begin to understand and respect each other more. Another idea is that Raven's sister gets possessed by an evil entity and Raven has to find a way to save her without harming her. It could involve Raven delving deep into her own powers and emotions to find a solution.
Another plot could involve a RWBY character ending up in the Naruto universe. Say, Weiss gets sent to Konoha. She might initially struggle with the different culture and the use of chakra, but eventually she could use her Glyphs in unique ways by combining them with chakra. This could also lead to some interesting interactions between her and the ninja students there.
A cool plot could involve the characters from Frozen getting stuck in the RWBY world and having to learn how to fight Grimm. Anna might be really eager to learn combat skills, while Elsa is more focused on controlling her powers in this new and dangerous environment.