Attis Attis is a highly intelligent super mutant and was an important commander in the Master ' s Army . After the destruction of the Master and the vats , he created the " Attis army " from remnants of the Master ' s army . He then began searching for clues regarding the history of FEV before trying to make the Master ' s plan a reality . He has a vindictive attitude towards the Brotherhood of Steel and around 2208 , he became their greatest enemy . He is the main antagonist and the final boss of " " . Background . Attis is one of the few super mutants with great strength , both intellectual and physical like the Lieutenant or Marcus . He is tall , strong and quite athletic for a super mutant . He is also very fast and knows how to use all kinds of weapons . After the death of the Master and the destruction of the vats , he created and became the general of the faction which tried to continue the Master ' s work ; rebuild the army and transform the entire human race into super mutants , to have a single race able to survive - thrive in the wasteland , eliminating any differences and removing all discord . After Attis created his own army , he took his group into hiding , searching for clues regarding the history of the FEV virus . Throughout the years , he and his army led a guerrilla war against the Brotherhood of Steel , ( still looking for the rest of the mutant army because of the failure of the Airship ' s expedition that created the Midwestern Brotherhood of Steel ) , eventually forcing Rhombus to start a crusade named " Texas Expedition " in order to annihilate the remaining super mutant threat . Attis learned about a secret Vault - Tec installation called the Secret Vault , the Vault - Tec private vault after the Great War , with new and possibly improved versions of the FEV virus . He led his group to the ghoul city of Los in Texas , where the Secret Vault was located . His first goal was to rebuild the mutant army and develop a cure for mutant sterility . The Secret Vault gave him hope , as the vault scientists ' research was dedicated to improving the original FEV in order to maintain reproductive functions . Arriving in Los , he tried to negotiate with the Church of the Lost , the cult that controlled the city , but in vain . Some time later a contingent of paladins of the Brotherhood of Steel , lead by Rhombus , arrived and a battle broke out between Attis ' army , the Church of the Lost and the Brotherhood paladins . The Brotherhood of Steel group was annihilated and Rhombus was captured . Attis used this confusion to his advantage and managed to get into the Secret Vault . But to access the laboratory section , he had to get a key card , only possessed by the Church of the Lost . Besieging the city to get the key card and going to war with the Church of the Lost . He continued to develop his plan and allied himself with Jane , the raider matron from the largest and most powerful raider gang in Texas located in Carbon . She sold him human slaves from raids in Carbon , and he goes into Carbon himself to retrieve them personally . They now became slaves of Attis but their function in his army remains unknown . Continuing his plans for the war against the Church of the Lost and to get the key card , the Initiate changed the deal , destroyed a weakened Church of the Lost , killed , the high priest of the cult and came to the Secret Vault to destroy both Attis ' army and the Secret Vault with the key card stolen and hidden by Rhombus , preventing Attis from exhausting his army in a long drawn - out siege . Refusing to give him the key card , Attis engaged in combat , using his retractable arm blade to fight . Though he loses , two nightkin appear and quickly stun and capture the Initiate . Taking him to an area with a huge pit down in the Secret Vault ruins . Attis took the key card , cut off his arm and commanded the nightkin to throw him into the pit . However , thanks to , the Initiate managed to survive and later even received a new arm through a regeneration experiment . Attis penetrates deeper into the Vault , until the last section of the laboratory , the laboratory core and found the Vault - Tec modified FEV . Just before the Initiate arrived and combat started , he tested it on himself . It was revealed that this FEV is unable to make mutants fertile . However , an unforeseen consequence followed , revealing another potential of the Vault - Tec modified FEV , it led to a strange side effect and his skin turned darker . During the battle , he mutated again , growing and reaching the size of a super mutant behemoth and all his injuries were healed . After being seriously injured again by the Initiate , the modified FEV proved highly unstable , causing Attis to regenerate uncontrollably due to the amount of damage he received . He exploded and coalesced into a strange biomass , a rapidly - multiplying multicellular organism that covered the entire laboratory section of the Secret Vault . Though initially he believed his discovery lead to nothing , soon he began to realize the new potential of the virus . This new creature began to grow with each second , and its various organs , eyes , mouths and tentacles began to grow out of the floor . This organic nightmare retained some of Attis ' conscious , starting to dream of a new world , similar to the Master ' s Unity . In this gigantic form , Attis tried to make the remaining super mutants in the Secret Vault " join " him , but they were scared of him and fought back . The Initiate ran from him , fighting his tentacles , his giant " heads " with one eye and several fleshy walls with big mouths in the center of them . Eventually , he found Patty , the vault security officer , now enveloped in a cocoon - like state by Attis , being slowly digested . She revealed that there was a way to start a self - destruct sequence , and asked the Initiate to kill her . In the next room , the needed terminal was found , and the Initiate escaped using the vault ' s , while the vault ' s nuclear warhead , specially designed for this purpose , detonated , killing Attis . Appearances . Attis appears only in " " .