One plot idea could be a team of RWBY characters getting teleported into the Fallout New Vegas wasteland. They'd have to adapt to the harsh environment, deal with radiation, and face off against the various factions in the game. Another could be a character from Fallout New Vegas traveling to the RWBY world and learning about the concept of Dust and Huntsmen.
In some Fallout New Vegas RWBY fanfictions, the plot could involve a fusion of the two worlds' magic systems. For example, the Vault - Tec technology in Fallout New Vegas could somehow interact with the Dust - based magic in RWBY. Maybe a group of scientists in Fallout New Vegas discovered a way to harness Dust, but it had unforeseen consequences on both worlds. Or there could be a story where characters from both universes had to work together to stop a common enemy that was using the power of both the wasteland and the Grimm to take over. This would require them to combine their skills, like the combat abilities of RWBY characters and the survival skills of those in Fallout New Vegas.
A more complex plot might be that there is a dimensional rift that is causing chaos in both universes. Characters from both Fallout New Vegas and RWBY have to work together to close the rift. In the process, they learn about each other's worlds, values, and fighting styles. The contrast between the post - apocalyptic technology and magic - based abilities in RWBY could lead to some really interesting interactions and story developments.
One idea could be creating an OC who is a hunter from RWBY world but ends up in the Fallout New Vegas setting. They could use their unique weapon skills from RWBY, like using a scythe in combat, and adapt them to the post - apocalyptic world. Maybe they team up with some of the factions in New Vegas while also trying to find a way back home.
A plot idea could be that the Courier discovers a powerful relic in the Fallout world that has the power to connect different universes. This relic accidentally transports the Courier and some of the key RWBY characters to a strange in - between realm. In this realm, they have to work together to find a way back to their respective worlds while also facing challenges that are a mix of both Fallout and RWBY elements, like Grimm - like creatures with post - apocalyptic mutations and bandits with Dust - powered weapons.
A plot could involve a group of settlers from Fallout 3 trying to make a new start in the Mojave. They run into trouble with the various factions in New Vegas. Meanwhile, a character from New Vegas goes to the Capital Wasteland to learn about their different ways of survival. This leads to an exchange of ideas and technology between the two groups, as well as some clashes due to different values.
One idea could be creating an OC who is a former NCR soldier turned bounty hunter. They could have a complex backstory of disillusionment with the NCR's politics and find a new purpose in tracking down dangerous criminals in the Mojave Wasteland.
One idea could be exploring the backstory of a minor character in the game, like a random caravan trader. You could create a whole story about how they got into the caravan business, their adventures on the roads, and the dangerous encounters they've had. Another plot could revolve around a new faction emerging in the Mojave Wasteland, and how it affects the existing power balance among the NCR, Legion, and Mr. House. Maybe this new faction has a unique ideology or technology that shakes things up.
You could write a fanfic about the origin of one of the factions in Fallout New Vegas. Let's say the Powder Gangers. Maybe they were once just a group of miners who were mistreated and decided to take up arms. Show how their ideology evolved from a simple quest for justice to the more chaotic and violent group we see in the game.
One common theme is the clash of different worlds. RWBY has its own unique setting with magic and Huntsmen, while Fallout New Vegas has a post - apocalyptic wasteland. Writers often explore how characters from RWBY would adapt to the harsh environment of Fallout New Vegas. Another theme is the power struggle. In both universes, there are different factions vying for power, and fanfictions may focus on how these factions interact when combined.
Survival in a strange new world is also a common theme. RWBY characters might find themselves in the harsh wasteland of Fallout New Vegas, having to scavenge for resources and deal with the various threats. This can be used to show their growth and development as characters. Similarly, Fallout New Vegas characters could be thrown into the RWBY world and have to learn about the Grimm and the different power structures there. It creates a lot of opportunities for exciting adventures and character - building in the fanfiction.
A common plot point is the struggle for medical resources. In the post - apocalyptic world of 'Fallout New Vegas', finding proper medical care for a pregnant woman is extremely difficult. So, the character may have to embark on a dangerous journey to find a doctor or medical supplies.