Maybe the RWBY characters are on a quest in Skyrim to find a way back home. Along the way, they meet various characters like the Dark Brotherhood or the Thieves Guild. Ruby might befriend a young Nord who is also an aspiring warrior and learn some of the local combat techniques. Weiss could use her knowledge of Atlesian technology to improve some of the weaponry in Skyrim. Blake could uncover some secrets about the Daedric Princes that are related to the Grimm in some way, and Yang could participate in the Skyrim's famous brawls and earn a reputation as a fierce fighter.
One idea could be that the Dragonborn is somehow transported to the RWBY world. They could use their shouts to combat the Grimm. For example, 'Fus Ro Dah' could send Grimm flying back, and the local Huntsmen and Huntresses are both amazed and a bit wary of this new power.
A great idea for an RVB RWBY crossover fanfic could be a tournament - style story. Characters from both universes are forced to participate in a huge tournament. This would allow for a lot of different match - ups between the characters. The Reds and Blues' comical and sometimes unorthodox fighting styles would contrast with the more refined and trained fighting styles of RWBY characters. It could also lead to some interesting friendships or rivalries forming during the tournament.
One idea could be to have the Spartans from Halo end up in the RWBY universe. They could team up with the RWBY characters to fight against a common enemy like the Grimm. Maybe the Spartans' advanced technology would be a big advantage in battles.
Well, a cool concept for an Overwatch RWBY crossover fanfic would be to focus on the technology aspect. Overwatch has a lot of advanced tech, and RWBY has its own unique Dust - based technology. The fanfic could explore how the two types of technology interact. For instance, Mercy's healing staff could be affected by Dust in the RWBY world, or Torbjörn could use RWBY - style materials to upgrade his turrets. And of course, the character interactions would be great. Winston and Zwei could be an interesting pair to write about.
A possible idea for a MHA RWBY crossover fanfic is to explore the idea of semblance and Quirk evolution. The characters from both shows could train together and discover new ways to enhance their abilities. For instance, Izuku Midoriya could learn from Ruby about using her Crescent Rose in combat and in turn, show her how to better control her power flow. The cultural differences between the two worlds could also add depth to the story, like how the heroes in MHA are more publicly recognized compared to RWBY, and how the characters react to this disparity.
One idea could be that Godzilla arrives in the RWBY world due to a strange dimensional rift. The Huntsmen and Huntresses initially see it as a huge threat and try to fight it. But then they discover that Godzilla is actually there to fight a common enemy, like a new type of Grimm that is immune to normal attacks but vulnerable to Godzilla's atomic breath.
One idea could be to have the RWBY characters team up with Halo Spartans to fight a common enemy. For example, a new type of Grimm that has been enhanced by Covenant technology. The different fighting styles of the RWBY characters, like Ruby's scythe - wielding and Halo Spartans' high - tech combat maneuvers, would create some really cool action scenes.
One idea could be that the Grimm in RWBY are somehow related to the beasts in Bloodborne. Maybe there's a common origin or a dark force that controls both. For example, the Grimm could be an earlier form of the Bloodborne beasts, and the Huntsmen and Huntresses have to deal with a new type of Grimm that has the characteristics of the Bloodborne creatures, like a more sentient and intelligent type of Grimm.
One idea could be a character from Skyrim accidentally stumbling into the world of Enderal through a mysterious portal. They then have to adapt to the new and often harsher rules of Enderal while also trying to find a way back home. Maybe they form an alliance with an Enderal native who is also on a quest, and together they face the unique challenges of both worlds, like the different magic systems and political landscapes.
A crossover could involve the magic systems. Zelda has its own brand of magic, and Skyrim has a complex magic system too. Maybe a mage in Skyrim discovers a way to open a portal to Hyrule and brings back some magic items or spells. This could cause chaos as the two different magics interact in unexpected ways. The dragons in Skyrim might be interested in the new magic, leading to some epic battles.