Master

The Master or Master of the Super Mutants is the founder and leader of the Unity, a mutant-led organization with the goal of unifying all humanity by transforming them into mutants. He is fused with the Cathedral's computer network.

Background
The Master was known as Richard Grey before leading the Unity. His friend Harold described him a brilliant doctor and philosopher. Harold was part of an expedition led by Grey to the Mariposa Military Base, where caravans reported creatures emerging and attacking from. Vault Dweller: "Where were the mutants coming from?" Harold: "Everywhere! Hell, seemed like you couldn't fart without hitting one. But mostly in the northwest." The Vault Dweller: "Did you explore that area?" Harold: "We mounted an expedition. God, Richard. Richard Grey. Led a small group of us up there." The Vault Dweller: "Richard Grey?" Harold: "Richard Grey was a doctor. Little older than me, and friend was he smart. He found the source." The Vault Dweller: "And what was that?" Harold: "Some sort of old military base. We lost a lotta folks getting in there." The Vault Dweller: "How did you know this base was the cause?" Harold: "Because it was like someone went bargain shopping at mutantland! Geez! Cheaper by the dozens! Can't figure any other reason except that being the factory." The Vault Dweller: "Did you examine the base closely?" Harold: "We got pretty far inside. Wasn't a lot of us left by then. Grey, me and couple of others." The Vault Dweller: "And then?" Harold: "One of them robots got Francine. Mark was wounded, sent him back to the surface. Then it was just me and Grey." The Vault Dweller: "What ever happened to Mark?" Harold: "To this day, I don't know. He never made it back here, and...well I...couldn't face the wasteland again, so I...I never looked." The Vault Dweller: "What about you and Grey?" Harold: "We made it to some sort of central core, like a plant of some sort. That's when it happened." The Vault Dweller: "What?" Harold: "A robot crane crashed into us. Last I saw of Grey, he was flying through the air in-into some sort of acid bath. I was in bad shape and...well I passed out." The Vault Dweller: "How did you survive?" Harold: "Well, I have no idea. Woke up in the wasteland, barely hanging on. Got lucky and some traders I knew found me days later. Good thing, since I was already changing. They brought me here, and here I've been since." The Vault Dweller: "How did you mutate?" Harold: "All's I know, is it was something inside that base." The Vault Dweller: "Do you think it could have been radiation?" Harold: "How the hell should I know? Grey would've known if anybody could. [sigh] Anyway, that's how the deal went down." (HAROLD.MSG)

Richard Grey's audio diary is found in the Mariposa Military Base, which describes a first hand account of mutation after he was knocked into vats of FEV by a crane. He describes the green slime that he was immersed in and that it is the source of all the mutations his group traced to here. He wrote that at first, his skin peeled and festered, and the experience was painful. He recounted how he regained his ability walk and felt stronger, and described the experience of a tendril growing from his stomach which he used to consume other creatures.

Grey commented that he had previously thought his mind was slipping into hallucinations, but now was improving. In an attempt to see if animals would also gain awareness from the virus, Grey dipped a rat and a dog into the vats, and they became fused together. At this point, Grey stated he was "much more than a human now" and began commenting on his plans to "bring others into the glory that is the Unity."

Once Grey developed a neurolink into the military base's computer, he learned that the virus was called FEV and began to intentionally modify himself by way of injecting the virus into his body. He dipped humans that he caught into the vats, but described them as disappointments, the virus mutating them into "big and dumb mutants." When Grey caught and mutated a human that had less radiation damage, he noted that the conversion was more successful. He then sought to expand to a new "unification center" in order to continue his vision.

Grey subsequently began calling himself the Master and sought out radiation-free humans to transform into super mutants using what he referred to as FEV-2. One of the Master's direct reports, the Lieutenant, explained that the virus itself was mutated by radiation after the war, and that humans living in the wasteland have been exposed to this mutant FEV, inoculating them from the full effects. Individuals such as those living in vaults have limited exposure to this mutated virus and are still susceptible to its effects. In addition to dipping subjects in the vats, some were experimented upon with FEV, the virus injected into various parts of the brain.

The Master enlisted the aid of Morpheus and his doomsday cultists as a public front and settled in the Cathedral. The cathedral was guarded by the nightkin, which were super mutant elite troops equipped with Stealth Boy technology. The Master developed psychic powers and anyone who was granted an audience with him must wear a psychic nullifier to pass through the Corridor of Revulsion. If the Master is destroyed, Leanne mentions that the surviving mutants fled in different directions.

Quests

 * Destroy the Mutant leader: The Master is the mutant leader and needs to be destroyed. The Vault Dweller has three options to choose from:
 * Combat includes facing the Master directly. He has 500 HP, a Gatling laser, high AC, and can attack twice per round. Furthermore, he will spawn a super mutant in the corridor every two turns (four at the lowest combat difficulty), up to a maximum of twelve. Hardened power armor and high damaging weapons are a necessity to withstand the damage output, however, the Master will not attack companions or his Floating Eyes. In fact, the robots are not aggressive towards the player and if splash damage hits them, they will turn on the Master.
 * A psychic nullifier is needed for dampening the Master's psychic attacks.
 * Because the Master is integrated into the Vault overseer's chair, he counts as a robotic enemy and is vulnerable to pulse grenades.
 * But an even greater vulnerability is the limited range of his Gatling lasers, which means that there is a window further away in the long hallway from where one can shoot him with a sniper rifle without him being able to retaliate.
 * Saving and reloading will also cause the spawned mutants to disappear but still count towards the maximum of twelve.
 * Diplomacy requires the player character to have read Vree's autopsy report and have at least 7 Intelligence and good Speech. Then it's a matter of asking him about the plan, pointing out a problem with it, and either giving the disk or telling him to ask his female mutants.
 * Stealth involves no confrontation and infiltrating the lowest level via the barracks in the command center. The doors are locked and require a good Lockpick. One can activate the bomb after killing the guards by using Science (70% required), Lockpick (70% required; the test was intended to be for Repair, but the game checks for Lockpick) or the bomb key looted from Mariposa.
 * Finally, it is possible to join his cause simply by talking to him and agreeing to his demands or persuasion. Doing so triggers the dipping ending and the raid on Vault 13, but grants no end slides.

Death animation

 * Killing the Master will trigger a unique death animation:

Appearances
The Master appears only in Fallout as a talking head. He is mentioned in Fallout 2, Fallout 3, Fallout: New Vegas and its add-on Dead Money, Fallout Tactics and Fallout: Brotherhood of Steel.

Behind the scenes

 * The Master is mentioned in the Fallout Bible, the Fallout Official Survival Guide, and Fallout 2 Official Strategies & Secrets.
 * The Master was going to be the main antagonist in the canceled Fallout movie.
 * On the Project V13 web page, during the introduction, the phrase "The Master Lives" is scratched into the desk.