A fanfic could also explore the backstory of how Cinder first encountered a Beowulf. It could be that when she was a young and inexperienced fighter, she had a near - death experience with a Beowulf. This encounter could have shaped her views on power and fear, and as she grows stronger, she constantly compares her current enemies to that first Beowulf she faced.
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.
Cinder would probably win. She has a wide range of powerful abilities like her fire - based powers. She can also be very strategic. A Beowulf, while strong, is more of a brute force creature. Cinder could use her speed and intelligence to outmaneuver it and then finish it off with her powerful attacks.
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.
One interesting plotline could be exploring Amber's powers in more depth and how Cinder might be affected or influenced by them. For example, Amber could have a hidden ability that Cinder discovers and tries to use for her own gain.
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.
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 a prequel - type fanfic that shows Cinder's life before she became a villain. It could explore her training, her early encounters with the forces that led her down the dark path. Another idea is a fanfic where Cinder has to team up with Ruby and the gang to fight a greater threat, forcing her to put aside her enmity for a while. A third idea could be a fanfic that focuses on Cinder's relationship with her henchmen, showing a different side of her leadership style.
Another idea is a time - travel fanfic. Cinder travels back in time and meets a younger Ruby. She could try to manipulate Ruby into following a different path, but Ruby's strong will and sense of justice might resist. This would create a lot of conflict and interesting character dynamics as Cinder tries to change the future and Ruby tries to protect it.
One good theme could be her redemption. Many fanfic writers might explore the idea of Cinder turning away from her villainous ways and seeking to make amends for her actions. This could involve her having to face the consequences of her past deeds and trying to find a new path in the RWBY world.
One idea could be a crossover where Cinder somehow gets transported to the Naruto universe. She might initially try to use her powers to gain control, but then realizes she has to adapt to the new chakra - based powers. Meanwhile, RWBY characters could also end up in the Naruto world in search of Cinder and end up forming unexpected alliances with Naruto and his friends.
One idea could be a fanfic that explores the backstories of minor characters in RWBY more deeply. For example, you could focus on a character like Velvet and create a story about her training before coming to Beacon. Another could be a crossover within the RWBY universe itself, like a team-up between different schools' teams that we haven't seen much of in the official series.