you have to be fucking kidding me
Just a reminder that Bethesda actually thought this was an acceptable way to end a story.
me: hey fawkes can you walk five feet into this room and type 3 numbers on a keyboard for me? since i saved your life and all?
my best friend fawkes: tbh dude i could but it’d be cooler if you just fucking died
It just struck me this game’s like a decade old now, so for the uninitiated, to the best of my recollection: the final room’s dilemna is to fix a water purifier there’s a chamber with SUPER LETHAL radiation that needs to be entered so someone can input some password on a numberpad to fix it. You can either go in yourself and die or send in the girl who came with you and have her die, and since at launch there was no postgame and the game simply cuts to the an ending cinematic and credits after this decision either way without the appropriate DLC (and when you do get the DLC it retcons that you somehow survive either way), it doesn’t really matter except whether you care about the narrator calling you a coward or not in the photo reel at the end. BUT, and I swear this must have been like a last minute addition that the writer’s completely forgot they’d written themselves into a corner with because they’d already decided on a STELLAR ending. One of the few travelling companions in this game, in fact perhaps the only one you gain directly from the main quest, a mere hour or two before this final room, is Fawkes. He’s got 2 important character traits: Friendly, which is odd for a supermutant in the bethesda canon, and Immune to Death By Radiation, a trait that is not only common to supermutants, but DEMONSTRATED in the quest just before this one. Like an hour ago of gameplay, there was an irradiated room you couldn’t enter to get this macguffin you need, so after some pleasantries, the solution to this puzzle is to have your new friend Fawkes go in and grab it for you effortlessly. It is in fact the only solution to that puzzle, it is the one plot-critical thing that Fawkes is notable for. So your options, to review: sacrifice yourself, or sacrifice another human. Or ask Fawkes to do it so no one has to die, and have him tell you in the most pretentious way to go fuck off and die in the radiation room, buddy.
There is also a ghoul companion who is canonically your slave and immune to radiation and yet somehow in this instance he’s able to say no because what the fuck ever I guess 
Not that anyone asked, but I figured I’d add some extra context and details.
The main plot of Fallout 3 starts with your character venturing out into the irradiated wastes to find your missing father. That’s important here because the water purifier the game ends at is his life’s work, and The Deadly Radiation Chamber is filled with deadly radiation because he sacrificed himself trying to keep it out of the hands of a fascist paramilitary organization. So your story starts with following your father out of the Vault and ends with following him into the grave.
Now with some good writers and in the right type of game, you could make something like that work. As the sudden twist ending at the end of a sprawling sandbox RPG specifically made by Bethesda, not so much. And especially not when half of your potential companions are much better suited to the job.
Calling Sarah Lyons “the girl who came with you” is selling her very short, but not any worse than the writers do. She’s literally a knight in shining armor who’s sworn to lay down her life to protect the innocent, and also technically your superior officer since you got drafted into the Brotherhood of Steel. She’s the only one who’ll actually go in for you in the original ending, but she’ll also scornfully state “so much for chivalry” before she does it. To reiterate, the high ranking knight gave you the choice and then gets upset when the scared teenager doesn’t want to die in her place. A lot of her character and personality is told instead of shown because Bethesda, but even then it’s a major break in character compared to her first appearance where she lead a small detachment against overwhelming odds to protect a single civilian.
Fawkes has already been covered in detail but on top of already having done something very similar for you, he’s also usually one of the kindest and most philosophical characters in the game so having him say it’s your destiny to die here is another huge character break.
Charon is a ghoul which means he’s not only immune to radiation but actively healed by it, and if you hold his contract his unique code of honor compels him to do whatever you tell him no matter what his personal wishes. He’ll tell you to get bent if you ask him to do this one task too, but to be fair it’s actually more consistent with him. He very clearly resents his contract and enjoys taking every opportunity to rules lawyer any degree of freedom from it. IIRC there’s another point where he tells you he’s a bodyguard not a delivery boy.
Sergeant RL-3 is a robot and has no such excuse.
But in my view the absolute worst is Paladin Cross, another literal knight in shining armor who is even more committed to protecting the innocent. But she also has even more history with your father than you do. She helped him build the purifier in the first place, has been protecting him and even you since before you were born, and if you talk to her about his death she’ll say that it was for a worthy cause and hopes that she can give her life equally as well. But when given the choice to do exactly that, she balks.
