When the Lone Wanderer (the player in Fallout 3) emerged from Vault 101 to go in search of his father, he couldn't have predicted that he'd end up playing a key role in a war between the Brotherhood of Steel and the Enclave. The Wanderer's father, James, dedicated his life to Project Purity, an endeavour that aimed to provide pure water to the whole wasteland. The Enclave, a shadow of its former power but still influential on the east coast, was up to its old tricks, and tried to infect Project Purity with FEV, which would kill all mutants, ghouls and wastelanders. The Lone Wanderer thwarts this plan, and then joined the Brotherhood of Steel in an all-out assault on the Enclave, destroying the group as a major power in the wasteland.