Token Evil Teammate / Fallout

• Myron from Fallout 2, the teen inventor of Jet, whose evil extends to potentially drugging and raping a female PC with a very low intelligence score. He is intended, to all appearances, to be a Hate Sink (being annoying, beyond the Moral Event Horizon, AND bad in combat) which everyone will only use for his ability to craft drugs for the player if given the necessary ingredients. He's easy to keep in line just with threats, since he's so pathetically weak in every way. Even if you let him live, he gets murdered in some back alley by a random Jet addict in the epilogue, regardless of your actions. Even the writers couldn't stand him.
• Fallout 3: Jericho is a former raider, who are notorious murderers, rapists, sadists and possibly cannibals depending on the particular gang. Though he nominally works as a part-time protector for the settlement of Megaton, he usually ends up getting drunk off his ass and reputedly attempted to rape one of the local residents. A player with bad karma (and 1000 caps) can convince him to come out of retirement and become a companion. He'll stay on your side even if you turn good after recruiting him, but he'll often complain about it.
• Fallout: New Vegas:
  • The Omertas are this for the Three Families on the Strip. The Chairmen and the White Glove Society have their good and bad members, but every Omerta you meet is a vile bastard. (This is assuming you don't count Carlitos, who's no longer an Omerta partially because he's a pretty decent guy.)
  • Orion Moreno of the Enclave Remnants. The others were basically good people who joined the Enclave to bring order to the Wasteland and regularly subverted their more vile orders (and one of them outright quit the organization even before its defeat by the NCR), but Moreno is a bloodthirsty true believer in the Enclave's fascist ideology who's not a bit sorry for the innocent people he killed.
  • Joshua Graham was originally supposed to be one of these in Fallout: Van Buren, where he was known as The Hanged Man. However, due to the fact that J.E. Sawyer decided that this did not make for an interesting character, Graham appears in New Vegas as a deeply conflicted yet incredibly brutal Atoner. (After being alluded to a number of times in the base game as the co-founder of Caesar's Legion and considered ruthless and merciless even by their standards.) Also, Ulysses was originally meant to be a Legion-affiliated companion (and in the game was a former Legion spy/scout) but was cut from the game proper, though he becomes the central figure of the Lonesome Road DLC.
  • In DLC Dead Money, Dean Domino plays this role, being practically responsible for everything that went wrong with the Sierra Madre due to being jealous of the creator. If the player gets on his bad side, he will try to kill you off near the end.
  • Colonel Cassandra Moore is this to the NCR. While most of the NCR higher ups are Reasonable Authority Figures (Hsu, Crocker) or at the very least flawed antiheroes (Hanlon, Oliver, Kimball), Moore is an outright sociopath and sadist who gleefully advocates mass murder, constantly insults and belittles the Courier (especially if they solve her missions peacefully), and in general comes across as a psychotic, bloodthirsty warmonger. Lead developer Josh Sawyer changed her karma from Neutral to Evil in his unofficial patch.
  • Averted in the base game, where none of the in-game companions are even close to evil. At worst, Raul is the only Companion who has no problem with the Legion since he's personally seen that Arizona is actually safer under their control.
• Fallout 4:
  • Cait is a Psycho-addicted pit fighter who tends to favor selfish and vicious actions as well as chem usage. However, if you help her kick her habit, she starts to ease off and will dislike it when you use chems.
  • As an Institute Courser, X6-88 is an agent of the most morally questionable major faction of the game. He tends to disapprove of anything not related to helping Institute cause, such as general acts of charity.
  • While Strong is a partially reformed Super Mutant, he's the most brutish of the companions and much more like his kin compared to past Super Mutant companions like Marcus, Fawkes or Lily. He's the only companion that approves of killing random people^note Until Porter Gage, who likes it less than Strong but does approve of it and cannibalism, though he also approves of altruism to an extent. This is more due to super mutant nature and culture than him being actually malicious or cruel. You can be a paragon of virtue or a psychopathic mass murderer, and Strong will approve either way. What he disapproves of is if you try to ride the fence and be a mercenary motivated by your own gain.
  • Porter Gage of the "Nuka World" DLC is perhaps the most evil companion of the game. Cait and Strong at least have the excuse being mentally unstable due to drug addiction and mutation respectively, and X6-88 was created to be a cold and efficient enforcer. Gage is a very ambitious and sadistic, if surprisingly friendly and pragmatic raider. He only aids the Sole Survivor when he realizes they would make a better leader and forge a better gang than his current employer. If you decide to overthrow the raiders in Nuka World, Gage will turn on you, no matter how high your affinity with him is or how much you've been through together.