One idea could be a character from the Enclave finding themselves in a situation where they have to team up with a group from the Fallout world they usually oppose. Maybe a lone Enclave soldier gets separated from his unit and is forced to rely on a group of wastelanders to survive. This could lead to a lot of character development as he sees a different side of the world outside the Enclave's ideology.
Another plot could involve a scientific experiment gone wrong in the Enclave that creates a rift and pulls in elements from different parts of the Fallout universe. For example, mutants from one area and high - tech Enclave gear start mixing in a strange new location. Characters from both sides then have to figure out how to deal with this new and chaotic situation, which could be full of action and mystery.
For characters from the general Fallout world, think about their experiences. They've grown up in a harsh, post - apocalyptic world. So, they might be more resourceful and street - smart. They could have a distrust of authority figures, especially those from the Enclave. When writing interactions between the two types of characters, use these differences to create conflict and tension.
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 that the Dragonborn from Skyrim somehow gets transported to the post - apocalyptic world of Fallout 4. Maybe they have to deal with the new threats like the raiders and mutants using their dragon - slaying skills. Another plot could involve the Sole Survivor from Fallout 4 finding a way into Skyrim and getting caught up in the civil war there, having to choose a side while also trying to find a way back home. Or perhaps a magical artifact from Skyrim ends up in Fallout 4 and causes all kinds of chaos as different factions fight over it.
One idea could be a character from Fallout finding themselves in Skyrim. Maybe they bring their advanced weaponry, like a laser pistol, into Skyrim's medieval - like world. This would cause quite a stir among the locals, who have never seen such technology. The character could then get involved in Skyrim's political intrigue, using their unique skills to help or hinder different factions. Another plot could involve a Skyrim mage traveling to the Fallout wasteland. They would be amazed by the strange, post - apocalyptic magic (technology) there and try to learn about it, while also using their own magic to survive against the mutated creatures.
One interesting story could be about an Enclave OC (Original Character) who tries to reform the Enclave from within. This OC might face opposition from the more traditional and power - hungry members of the Enclave, but through determination and some unexpected alliances, they start to make changes.
One interesting story could be about an Enclave OC who tries to reform the Enclave from within. This OC might see the flaws in the Enclave's extreme ideology and work towards a more inclusive and less tyrannical organization.
One idea could be that the RWBY characters find themselves in the Fallout wasteland. Ruby could use her Crescent Rose to fend off mutants. Weiss might struggle with the harsh and dirty environment compared to her usual clean Atlesian surroundings. Blake could use her stealth skills to navigate dangerous areas, and Yang's strength would be useful in combat against raiders. They could be on a quest to find a way back to their own world while also trying to make the wasteland a better place.
Maybe the Forerunner technology in Halo could be related to some of the pre - war technology in Fallout. A story could explore how the two different technological systems interact. For example, the power armor in Fallout could be enhanced with Forerunner tech, creating a new super - powered suit.
One idea could be that the characters from RWBY end up in the Fallout wasteland. Ruby could use her scythe skills to fight off raiders and mutants. Weiss might use her glyphs to protect the group from radiation in certain areas. Another idea is that the Dust from RWBY could be a valuable resource in the Fallout world, leading to various power struggles.
Some of the existing Fallout 4 characters who interact with the Enclave OCs can also become popular in these fanfictions. For instance, Preston Garvey might be popular if he has an interesting dynamic with an Enclave OC, such as trying to convince the OC to work with the Minutemen for the greater good of the Commonwealth.