The Major Factions of Fallout 5 are the most significant groups in terms of sheer numbers, relation to the main questline, number of side questlines and overall amount of intractable characters. Interestingly these factions take a step away from the Main Questline in comparison to the four Factions of Fallout 4, this is due to the mixed opinions of the ending in Fallout 4 and has the player really only get these factions truly involved in the main questline if they go out of their way to help said factions.
There is one returning faction in Fallout 5, The New California Republic, three new versions of old factions in Fallout 5, The Super Mutant Collective, The Chinese Armed Forces & The United Khans and five completely new factions introduced in the game. These five new factions over new views on various issues such as solitude, self-reliance, communism vs. capitalism, human rights and freedom.
New California Republic
|The New California Republic (A.K.A. the NCR) are the largest existing organization of people in the US Wasteland, after many conflicts in their past they have become a dominant force of the West Coast of the USA and have expanded inland meeting competition with the Brotherhood of Steel, Caeser's Legion and numerous others. It is reported the NCR currently occupy up to 40% of the USA excluding Alaska and Hawaii. Their current competition in Central USA has been described as a mysterious force that has pushed in from the Canadian Border with extreme speed and power. This force is not shown in Fallout 5 however as the NCR wish to also liberate Alaska from the numerous Factions that have parts of the State under claim. The NCR are democratic and have strong bonds with the CAF & RCO although are distrustful towards APF, SMC & NUT due to their protection of Super Mutants.|
Super Mutant Collective
|The Super Mutant Collective (A.K.A. the SMC) are a small but immensley powerful group of Super Mutants. Possessing a potent mixture of the FEV Virus the were initially incredibly aggressive towards the surrounding APF territory capturing its residents and turning them into Super Mutants, however the APF appealed to the Super Mutants by providing them protection from the Black Skulls Gang in 2309 and thus the two formed an unexpected bond. The SMC are somewhat secretive towards the APF and very cautious around other Factions, the changing perspective of the Alaskan Lands however has helped the SMC reach out and become a valuable asset to its friends providing both Manpower (or Super Mutant Power, I guess) as well as numerous resources the Super Mutants refer to as "Petty Human Desires".|
Northern United Tribesmen
|The Northern United Tribesmen (A.K.A. the NUT) are a vast although low populated faction of individuals who believe in restarting humanity from the beginning, they believe the best way to rebuild is to relearn everything in order. They still value some basics such as Mathematics, Law, Literature, Some Sciences and History itself although they prefer to minimize their ability to fastforward the process. They are sometimes compared by other Factions to a Pre-War group called the Amish although lack the religious tendencies associated with that group. The NUT are generally peaceful although some of its younger members wish to leave and join other factions.|
Alaskan Protective Forces
|The largest and most dominant force in Alaska, the Alaskan Protective Forces (A.K.A. the APF) are regarded by most factions as a "Glowing Light in these Dark Times", they were one of the first gorups to adopt the belief of Super Mutant rights and had always been friendly towards Ghouls. They have shown considerable beliefs towards most organizations and have even made compromises with Raider-like Factions such as the Black Skulls Gang and the United Khans. The APF trade with most factions although desire independence of Alaska from the rest of the USA, an ideal that conflicts with the NCR. The two massive forces try to minimize conflicts although the tension has been evident and been rising especially in the last 40 years after numerous assassinations of major figure heads on both sides.|
Chinese Armed Forces
|The Chinese Armed Forces are a combination of the Chinese remnants from the Battle of Anchorage, citizens of the US Wasteland and refugees from the Chinese Marshes. Most people who are part of the CAF do so because they fear returning to the extremely dangerous conditions created in China after the war. Unfortunately due to tensions between the USA and China before the war the relationship the CAF has with groups like the APF & NCR is not fantastic. They have made peace treaties with these groups in the past however recent accusations of human slavery, torture and mutation have raised eyebrows from the opposition. In addition in 2382 there was a sudden law demanding a large percentage of the Super Mutant and Ghoul Population leave the CAF Territory sowing even more seeds of distrust. The most bizarre thing however is that despite these recent actions the leaders are incredibly kind to citizens within and even to Ghouls and Super Mutants who walk near the CAF Borders.|
Russian Command Organization
|The Russian Command Organization (A.K.A. the RCO) are the remnants of the East Russian Wastes. Forced to move due to a rapidly growing Radtick Population the groups banded together to form the RCO and settle in North-West Alaska. Safe from the Radticks the RCO faced a new issue, a displeased CAF and a hostile APF. The RCO attempted to mend the old wounds of the war with the CAF agreeing on an Allied Territory where anybody could settle from either side. The APF however were reluctant to let the RCO even onto the Alaskan front, ties between the two have strengthened over the last half-century with the RCO providing tactical support for the APF during a massive Orcant attack.|
Black Skulls Gang
|A highly organized group, inspired by the hatred and fear of other nations prior to the war. The Black Skulls Gang embodies many lifestyle options that other Factions would shy away from or call evil. the BSG as they've come to be known, doesn't particularly care about other factions' opinions of them however they use it as an excuse to terrorize, pillage and kill innocents in any faction. While not against new members joining they have strict codes of conduct for what Ghouls and Super Mutants are allowed to do, often getting the prior to work highly Radioactive Locations while the latter handle deadly animals the BSG keep.|
|Sirens||The seductive, highwaywomen of the Alaskan Wilds, the Sirens utilize both their physical appearance and incredible marksmanship to rob merchants blind, the pose a serious problem to the NCR and APF although the NUT seem mostly neutral about them. They have strong ties with the BSG especially considering the leaders of both gangs are siblings. The Sirens while almost exclusively female do allow some men to join if they prove their loyalty and are willing to sacrifice themselves to a belief all Sirens share called "The Great Purge".|
|The United Khans, like others before them, follow the ideals of the conquesting Khans of times, ancient past. They are a vicious yet low numbered group that utilize Yao Guais as a large proportion of their army. It is said the uniform is able to pacify Yao Guais on appearance alone. They are a vicious, terrifying group that strike fear into even the BSG and Sirens, seemingly undeterred by the priors disgusting acts of treachery and violence and the latters use of seduction. The United Khans pose a serious problem to the stability of civilization if they become powerful enough.|
Between the various major Factions in Fallout 5 there is a diverse and varied system of Relationships between them. If the player progresses signficantly through a certain Faction's Questline it will cause other Factions to react in various ways. There are four types of relationships; Ally, Neutral, Tension & War.
Allied Factions will help each other and if the player helps one they will help each other. In addition when regarding late Questline Missions the player will receive help not only from the Faction they joined but also that Faction's allies. Factions that are Neutral are unaffected by each other's presence this means that performing certain actions with one faction will not affect any Faction with a Neutral Relationship with it. If the player wants a Neutral Faction to the one they've joined to help them in late Questline Missions then as long as the Mission doesn't have the player conflict with an allied Faction of the Neutral Faction, the Neutral Faction will help.
Tension between two Factions can exist without the two Factions being in outright war with each other. Tension will not result in negative affinity if the player helps one faction while it has Tension with another Faction however directly attacking a Tension Faction's Allied Factions will cause Negative Affinity. In addition the player may face soldiers from Tension Factions in Missions. Finally Factions that are at war with each other will conflict when in sight, receive negative affinity for the player when they help factions one faction is at war with and if the player progresses through a Faction's Questline will result in damaging the territory of another Faction.