One idea could be to have the characters from RWBY encounter the Beasts in a shared realm. For example, Ruby could be intrigued by the unique abilities of the Beasts and try to learn from them while also teaching them about her own world's Dust magic. Weiss might initially be cautious but then find common ground in the Beasts' sense of honor. Blake could relate to the Beasts' more wild and primal nature, and Yang would be eager to test her strength against them.
In a fanfic, the crossover could start with a strange portal opening up and sucking some of the RWBY characters into the Beast world. They would be disoriented at first but quickly adapt. They could meet different types of Beasts, some friendly and some hostile. The RWBY characters would have to figure out how to get back home while also dealing with the various challenges in this new world. Ruby's leadership would be put to the test as she tries to keep everyone together and find a way back.
First, understand the lore of both RWBY and the Beasts. This will help you create a more believable crossover. For example, know the Semblances in RWBY and the powers of the Beasts. Second, focus on character development. Show how the RWBY characters change when interacting with the Beasts and vice versa. Third, create an engaging plot. It could be a simple adventure or a more complex mystery involving both worlds.
Perhaps in the fanfic, there's a human who is a collector of rare weapons. When he hears about Crescent Rose, he becomes obsessed with adding it to his collection. He tries all sorts of devious methods to get his hands on it, like tricking Ruby or stealing it during a battle. However, his actions have consequences as the other RWBY characters come after him to retrieve the weapon.
Ruby could interact with the main characters from Red vs. Blue. Maybe she tries to teach them some of her scythe - fighting techniques, and in return, they show her some of their military - style combat strategies. It would be an interesting exchange of skills.
A cool plot for a Rosario Vampire crossovers fanfic could be a time - travel scenario. The characters go back in time to the era when vampires were first created. They could meet the original vampire lords and learn about the true origins of their kind. This could also lead to a conflict as they might accidentally change the course of vampire history. Or perhaps there could be a crossover with a magical girl series. The Rosario Vampire girls could learn some new magical powers from the magical girls and use them to fight off a new threat that is immune to their normal vampire and monster abilities.
One idea could be to have the keyblade wielder from the original Keyblade world end up in a high - fantasy world like Middle - earth. The keyblade could be seen as a powerful and mysterious weapon, and the wielder might have to team up with characters like Aragorn to fight against Sauron. Maybe the keyblade has unique powers that can help turn the tide in battles against the orcs.
A common 'rwby crossovers fanfic' is the crossover with the world of Pokémon. RWBY characters could be trainers, and their semblances could have unique interactions with Pokémon abilities. For instance, Blake's shadow clones could be used in Pokémon battles in an interesting way. These crossovers often explore how the RWBY characters would adapt to the new world they are in and how their relationships would develop within that new context.
In RWBY Naruto crossovers, often you'll find fics that focus on the training aspects. Since both series have a strong emphasis on character growth through training. Naruto's intense training regimens could be introduced to the RWBY characters, and they could learn new ways to improve their combat skills. Maybe Weiss could learn some chakra control techniques to enhance her Glyphs. Another aspect is the teamwork. The RWBY teams and Naruto's squads have different dynamics, and when combined in a fanfic, it can lead to some great character development and exciting plot twists.
One interesting plot idea for a RWBY fanfic is to focus on a character's struggle with their semblance going out of control. This could lead to all sorts of problems, from accidentally harming their friends to attracting hordes of Grimm. Another plot could be a tournament - style story where teams from different kingdoms come together, not just the main RWBY teams. There could be rivalries, unexpected alliances, and new friendships formed during the tournament. Also, a plot where the characters discover a hidden power within the Dust that could change the balance of power in Remnant.
One idea could be Salem's reaction to the powers and technology in the Worm universe. Maybe she tries to use some of the parahuman abilities or advanced tech to further her own goals in the RWBY world.
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.