These super mutants were created in the "Evolutionary Experimentation Program", the experiment assigned to Vault 87. The modified strain of F.E.V. used to create these mutants resulted in a new strain of super mutant which, in addition to becoming sterile, grow larger and stronger as they age.
The first super mutants of this variety were created in 2078, becoming a permanent feature of the Capital Wasteland. Too dumb to overrun it, but too strong to die off. Their routine behavior included raiding to kidnap people for conversion with the EEP mutagen.
Their inability to reproduce (possibly bolstered by the FEV batch and/or human procreation instincts) leads to an obsession with preserving their species: they attempt to capture live humans as often as possible, in order to infect them with FEV, or "green stuff," at Vault 87. However, by 2277, the mutants are running out of FEV and are looking in desperation for a new source of the virus.
The inferior FEV strain used at Vault 87 retains the recursive growth patterns characteristic to FEV, but has a different effect, which may be also linked to how infection was performed in the labs. Test subjects were exposed a single time to FEV in isolated chambers, where virus was deployed as airborne particulate. When exposed, phenotypical changes occur within three days and include increased muscle mass, changes in skeletal structure and atrophy of all visible sexual characteristics, creating an uniform body shape devoid of genitalia or other sexual dimorphism. At ten days, skin pigmentation becomes a mixture of yellow and green, while its thickness and resistance to radiation and other environmental hazards rapidly increases.
However, a key problem with this batch is that the mutation does not stop. Within fourteen days of initial exposure, subjects regress to an almost feral state, exhibiting extreme aggression at every non-mutant. While some semblance of cognition is retained, exhibited by the ability to speak, operate machines and use basic tactics in combat, super mutants of this type are typically characterized by significant mental retardation. Another unforeseen side effect is that the unfinished virus strain codes the body for continued growth. If a super mutant of this type eludes death for prolonged periods of time, they may become a considerable threat, reaching the size of a small building.
Super mutant society is loosely hierarchical, with the weaker (most recently transformed) super mutants generally giving way to the stronger. The super mutant hierarchy can be roughly defined as such: grunt, brute, master, overlord and behemoth. The behemoths are so strong and savage that they are the only thing feared by other super mutants. Super mutants occasionally fraternize with one another and joke about puny humans or tell legends of other impressive mutants, like the rare behemoths - though their exchanges are limited in scope and a far cry from anything resembling a proper human language.
Despite their seemingly low intelligence, super mutants can sometimes employ effective military tactics. Melee-armed mutants will move in to engage the player while those behind them take pot-shots with ranged weapons. Super mutants armed with grenades will often use them without regard for any fellow mutants that might be caught in the blast radius.
When encountered at lower levels, super mutants are usually in groups of two or three, accompanied by one or two centaurs. At higher levels they can be found in groups of three to five, with a few centaurs acting as their watch dogs.
These are the weakest of the Capital Wasteland super mutants. They are usually encountered in groups of two or three, led by a stronger super mutant. Regular super mutants have almost twice as much health as most standard human non-player characters, but this is somewhat offset by their lack of body armor. Some of their prime locations are the GNR building plaza, the National mall, the Statesman Hotel, the National Archives, and Falls Church.
Super mutant brutes are generally stronger and tougher opponents than regular super mutants, as they are better armed and armored. They are the most common of all super mutants once the player reaches a high enough level, and are easily distinguished by their galea-like metal helmets and crude metal armor.
The super mutant masters are the group leaders of the mutant army which plagues the Capital Wasteland. They have the most hit points of all "common" super mutants. They're discernible by their armor which consists of black tubing which wraps around their lower and upper body and a fighter pilot helmet. A gas mask is strapped to their left shoulder, acting as a makeshift pauldron. They are generally never alone and are usually accompanied by one or two brutes. They tend to hang around old slaver settlements or abandoned towns, and they are rarely out in the open, wandering the wastes. Some reports suggest that they may also be found at abandoned Enclave facilities.
The super mutant overlords are variants added to the game in Broken Steel. They are aged, and powerful super mutants who already appear to be evolving into behemoths. Their intelligence (in comparison with other types of super mutants) is questionable, but they are smart enough to wield energy weapons. Sometimes, they are seen leading groups of other super mutants, but they more frequently tend to act alone, or in pairs. Overlords also have a 40 unblockable damage bonus when attacking with a tri-beam laser rifle and a 25 bonus when attacking with a special version of a super sledge. When carrying an assault rifle or a Chinese assault rifle, they use a one-handed pistol motion. They have a good chance of dropping above-average loot such as stimpaks, mini nukes, and purified water. They appear frequently at later levels.
The behemoths are the greatest threat among the East Coast super mutants. There are only five of these behemoths, although reports of their sightings continue long after the last of them are killed. They are the strongest of their kind, as well as many times larger than any other humanoid creature. They are usually armed with almost unrealistically large fire hydrants mounted on a large water pipe; other than that, they also use their enormous fists. Either way, both weapons are heavy-hitters, and will cause major damage against any enemy smaller than them.
If a super mutant picks up a pistol, it will use exactly the same attack animation as an assault rifle, which is a two-handed grip (the front hand is floating in front of the pistol). When shooting the pistol, their hands will shake from the recoil, as if the pistol is automatic.
Super mutants are not hostile towards giant ants or even mirelurks, but one can be seen fighting a pack of feral ghouls in the depths of Farragut West Metro Station. As can be proven by talking to Willow outside Underworld, non-feral ghouls are left alone by the mutants. This, in turn, is contradicted by the random encounter "ghoul friends" where they claim that they "couldn't make it past the super mutants".
After Broken Steel is installed, super mutants become rarer, and finding them will take some effort outside of spawning areas. Some super mutants can be heard talking that the "bucket heads" have been killing too many of them, this being their nickname for the Brotherhood of Steel.
"I have joke for you. Ready? Knock knock."
"Kill the humans! Kill them all! Aggghhh!!"
"Ha ha ha ha ha ha ha ha ha! Oh... oh... ha ha ha ha ha ha.... That a good one! Ha ha ha ha ha!"
"I was just wonderin'... What are you doing? Something good? Something fun? Me, I'm bored. Need somebody to kill. Or something to eat..."
"I was thinking. And it hurt! Hurt my head! But I remembered things. From before... I think I knew a woman. Or maybe, I WAS a woman... Aggh! It hurts!"
"Wish I had a new weapon. Something good to smash with. Wish I could hold one of those Behemoth clubs. So big! So much crush!"
"I need a new gun. I want something that won't break. Something that will shoot forever. One of us had... a Fat Man! I want one of those..."
"Have you found green stuff? I haven't found any. Ever. Maybe it's a lie. Maybe we're wasting our time. We could be out killing..."
"This is boring. We should be collecting more humans. We need more of us! The bucketheads have killed too many..."
"I'm hungry! I need something to eat. Meat would be good... A Brahmin head, roasted just a bit, with some..."
"I'll wear your bones around my neck!"
"I'm gonna eat your arms... when you're dead, human!"
"What you up to? Something fun? Something to eat? Me bored!" "Why you care?! You human or something?!" "Never mind! You too dumb to talk to!"
"I have a joke for you. Ready? Knock knock. Who's there? Humans. Humans who? Kill the humans, kill them all! Hahahahaha. Oh, that's a good one. Hahaha!"
↑ 1.01.11.21.188.8.131.52Fallout 3 Official Game Guide Game of the Year Edition p.42: "Super Mutants" "The Super Mutants that infest the urban ruin of Washington D.C. originated in Vault 87. Those unlucky enough to have reserved space in Vault 87 soon found themselves forcefully taken to a secure part of the vault, where they were locked in airtight chambers and exposed to a concentrated form of the F.E.V. The Overseer and his security force had no real idea what to expect; they were simply following the "plan." When the exposed vault dwellers started transforming into Super Mutants, nearly the entire vault population had been exposed. Those who hadn't yet metamorphosed knew what was coming, and, well...it didn't end well for humanity. The dwellers of Vault 87 were turned into Super Mutants in 2078, and have been a presence in the Capital Wasteland ever since. Most of those original Super Mutants have long since been killed. But whether it's because of the nature of the F.E.V. they were exposed to, or a simple underlying human instinct, the Super Mutants of the Capital Wasteland are obsessed with the preservation of their own species. Super Mutants are asexual and incapable of procreation, so their only way of reproducing is to kidnap other humans, drag them back to the Vault 87 chambers, and infect them with F.E.V. And so they have done, for nearly 200 years. Super Mutant society is loosely hierarchical, with the weaker (most recently transformed) Super Mutants generally giving way to the stronger. The Super Mutant hierarchy, as defined by the Capital Wasteland contingent of the Brotherhood of Steel, is as follows: Grunt, Brute, Master, and Behemoth. Generally speaking, the Super Mutants of the Capital Wasteland get bigger, stronger, and dumber as they age. The Behemoths are so strong and savage that they’re the only thing feared by the other Super Mutants." (Fallout 3 Official Game Guide faction profiles)
↑The Lone Wanderer: "Why did they build the walls?" Manya Vargas: "Well, the Raiders, for one. Once the town got big enough, they'd wait until the traders and their guards were away, then come in and clean us out! Now the Super Mutants... They were a whole other breed of problem. They'd kill us if they had to, but mostly they tried to drag people away! Alive! So, eventually, my father did something about it. Him and a few others organized the traders and the citizens and built the walls. So we're pretty safe now. Still, I wish those Brotherhood of Steel fellers hadn't hit on such hard times. They really helped keep the wolves at bay." (Manya Vargas' dialogue)