The Minutemen are the first faction you really get the opportunity to join. They're a nice, well meaning bunch who used to look out for the general population of the Commonwealth, until they fell to internal power struggles and failed to protect a settlement. After that everyone turned a bit sour on them.
The main purpose of the Minutemen seems to be maintaining as many settlements of humans as possible, and wearing cool cowboy hats. They're down on their luck when you first come out of the vault, but can gradually build up their numbers if you help them. They're just generally nice (if idealistic) guys who want to wipe out raiders and make the wasteland a safe place for everyone. Out of all of the groups the Minutemen requires the most amount of admin on your part.
Back to TopCodsworth will direct you into Concord almost immediately, where you can help Preston Garvey and his little ragtag group of survivors. Once you talk to Preston at Sanctuary he'll send you on missions to help protect settlements, and will make you the General of the Minutemen in no time, provided you accept. You'd think there'd be a more stringent vetting process, but nobody asks any questions.
Back to TopPreston gives you a flare gun, which you can use in a sticky spot to call on any sympathetic Minutemen nearby to help out in a fight. The usefulness of this does depend on how many settlements you've set up and how big they are, though. After completing the quests Taking Independence and Old Guns you get access to a huge sea fort and the ability to build artillery at settlements, respectively. Did we mention the cool cowboy hats as well?
Back to TopFor the most part the Minutemen can just stay under the radar, because mostly all they do is build lots of shacks in the middle of nowhere, and that's only if one person that they inexplicably put in charge can be bothered to do it. However, this does mean that they won't do anything to directly attack the Institute unless you yourself become an enemy of the Institute (by doing something extremely aggressive like killing a bunch of Institute scientists).
If you finish the main story with the Minutemen whilst also being enemies with the Brotherhood, the Brotherhood will turn up to attack the Minutemen, as is their way, but you can prepare for it.
Back to TopThe Institute was founded by a group of scientists who holed up in the basement of an old scientific institute, and ended up with a massive underground structure after generations of work was put in. Most people who now live in the Institute (which is all futuristic glass tubes and white walls) have never been to the surface, although not everyone who lives in the Institute is a person, depending on who you ask. The Institute developed incredibly advanced robots called synths, which in some cases are indistinguishable from humans, and in others are automatons with horrifying exposed faces. This has been viewed as a controversial move by other inhabitants of the Commonwealth.
The Institute is currently led by a mysterious bearded man called Father, fathers now being something of a trope for Fallout games.
Back to TopAfter a lot of effort. You have to have followed the main quest far enough to complete The Glowing Sea and Hunter/Hunted missions, and have links with one of the other factions to help you build the machinery to get you inside the Institute. Once you're in, though, you'll meet father and he'll start giving you errands to run just like everyone else in the game.
Back to TopYou get to teleport in and out of the Institute, and look at the nice indoor trees and synthetic gorillas they have there. You can also go to the tech wing of the Institute and speak to a young synth who asks you to collect seemingly random junk and, if you do, will give you a legendary laser rifle (called the Waser Wifle). There are also special Institute paint schematics for your power armour, and you can probably count the satisfaction at getting to kill some of the more smug NPCs in other factions.
Back to TopPretty much everyone hates the Institute. If you complete the quest Mass Fusion using Institute resources then you'll become enemies with the Brotherhood of Steel (and, if not then, the Institute will ask for your help in a war against the Brotherhood soon afterwards). Completing the quest End of the Line will destroy the Railroad, but you can tip them off and stall taking them out until a bit later. Just know that to stay with the Institute means attacking the Railroad at some point.
Back to TopThe Brotherhood of Steel are an old organisation and have appeared in all of the Fallout games in one way or another. They're a military group that has a pseudo-religious feeling (most of them worshipping a nebulous entity called The Creator), and whose members mistrust science and technology whilst simultaneously hoarding it for themselves, because theirs are the only hands that can safely wield it.
The Brotherhood believe that the near destruction of the world in the nuclear war was brought about by man's hubris, and technology being advanced too far and used for terrible means. By the time the Brotherhood members rock up in the Capital Wasteland they have an almost pathological desire to collect the technology still knocking about around Boston, and hate anything that isn't human – ghouls, super mutants, and synths – because they're representative of everything the Brotherhood hates. It's quite a totalitarian organisation and it's pretty much their way or the highway. Everyone you speak to will be incredibly serious, and slightly annoying.
Back to TopEarly on in the game you pass Cambridge and can pick up a military beacon leading to the Cambridge Police Station. There you'll find what remains of a Brotherhood recon team headed up by Paladin Danse (winner of the World's Least Interesting Man Award 2287). After completing the quest A Call To Arms with him he'll offer to officially induct you into the Brotherhood as an Initiate.
Later the rest of the Brotherhood shows up, with a massive airship named after a boat from Arthurian legend, which tells you exactly what kind of people the Brotherhood are. Once aboard that you can officially join as a Knight and work your way up from there.
Back to TopYou get a fresh new suit of power armour in Brotherhood of Steel paint, and access to the Brotherhood's armoury, which is kitted out pretty well (although you still have to pay for everything). You also get given some special tag grenades for signalling vertibirds, which can transport you across the map and are equipped with mini guns. If you complete the Brotherhood missions all the way to the end you get a jetpack for your power armour. Plus you get to call yourself a Sentinel, for whatever that's worth to you.
Back to TopRemember when we said the Brotherhood hate synths? Well they really hate synths. If you accept the Tactical Thinking quest (which comes after Blind Betrayal) then you become permanent enemies with the Railroad, so keep that in mind. You also immediately become enemies with the Institute once you start Ad Victoriam.
Back to TopThe Railroad makes it its business to smuggle synths out of the Institute to freedom by wiping their factory settings and implanting them with a new memory of an entire human life. Members of the Railroad make their home in some catacombs full of tombs underneath that famous church in Boston, and they have a robot called PAM.
Both the Institute and the Brotherhood are out to eventually eradicate the Railroad, and the Railroad in turn is hoping to take them out too. Everyone involved in the Railroad is pretty cagey and rude, but they live their lives in fear so you can kind of forgive them. They also apparently have ethical arguments about whether all robots count as living beings or not. They're a riot at parties.
Back to TopYou have to complete the quest Road to Freedom by following the Freedom Trail which winds through the Boston streets, and, conveniently, past some super mutants. Pay attention to the letters and numbers that your character reads from the road markers along the trail, because they give you the password to get into the Railroad's secret tunnels under the Old North Church. Once you're in you have to complete a quest with Deacon before the Railroad at large will trust you, but after that you're allowed to come and go as you please.
Back to TopFor completing that initial quest for the Railroad you get a pretty nifty silenced pistol. Eventually the Railroad give you a ballistic weave upgrade that you can apply to the cloth armour sets you wear under individual pieces (sets like the raider leathers, for example), which gives you some seriously overpowered damage resistance when you stack it all together. For our money it's the best of the unique faction rewards.
Back to TopThe Brotherhood of Steel and the Institute are both on the Railroad's hit list, so watch out for the Precipice of War and Rockets' Red Glare missions if you want to stay friendly with the Brotherhood. It's possible for you to lose your good working relationship with the Institute if you're fighting synths on a Railroad mission and don't kill them quickly enough, but you're generally okay until going ahead with The Nuclear Option quest with the Railroad. It's hard to balance staying allied with the Institute and the Railroad at the same time, since they're most actively working against one another.