|The following is based on Fallout: Brotherhood of Steel and has not been confirmed by canon sources.|
In a general sense, an initiate is any person who initiated into the Brotherhood of Steel.
When capitalized, the Initiate is the player character in Fallout: Brotherhood of Steel. Unlike the Vault Dweller, the Chosen One or the Lone Wanderer, he or she was not a native or a Vault descendant. The Initiate can be:
- Cyrus, a human tribal born in farming village.
- Nadia, a human orphan living on the streets.
- Cain, a former ghoul mercenary in Set's army of Necropolis.
Brotherhood of Steel members have gone missing in Carbon, and the Initiate is tasked with searching for the paladins, starting with the nearby town. There, he fought the Jane Raiders, and met the Vault Dweller, the hero of Fallout, who told him that the paladins were in the city of Los.
In Los, he met Harold, a strange FEV mutant and Giese, a former technician of Secret Vault, which gave some indication of where this was found paladins and told him that the Super Mutants found in the vicinity. Once in the torture chamber of the Church of the Lost, he found only Rhombus, sole survivor of the Brotherhood of Steel members, and fought Blake, the High Priest of the Church of the Lost. After the death of Blake, he escorted Rhombus to a truck where he had hidden a key card for the Secret Vault, the destination of the super mutants.
But while he recovered the key, Rhombus was found by kamikaze ghouls. After the fight with many kamikaze ghouls, Rhombus, seriously wounded, gave the Initiate the key card and entrusted the task of stop the super mutants. The Initiate asked for information of Los ghouls and Giese said a leading Warehouse Secret Vault to find this not far from here. He found the warehouse and goes inside.
After fighting in the Warehouse, he managed to revive an old generator and took an elevator that overlooked the entrance to the Secret Vault. In the Secret Vault, he happened to go to the control center where Attis, the super mutant leader, was waiting. During this battle with Attis, he learned that Attis was looking for something in the laboratories area, but was knocked unconscious and left for dead. With help from the human residents of the Secret Vault, the Initiate was revived and entered the ruins of the Secret Vault, to reach the last sector of the laboratory, where Attis was looking for something.
Arriving in the latter zone, he met Attis and fought him again, but during the battle, Attis mutated into a blob mutant. The Initiate fought through the blob in order to gain access to a computer terminal that can start the decontamination of the Secret Vault. The Initiate then sprinted to a monorail car in order to escape the self-destructing facility.
The Initiate managed to escape and had gone several miles away from Los and the Secret Vault, which was exploding into debris. After these events, it is unknown if the Initiate remained in the Brotherhood of Steel or if he left to wander the wasteland.