War. War never changes.
In the year 2077, the great trial of Humanity was concluded when the verdict was delivered with the gavel of nuclear armageddon. Humanity had become it's own judge, jury and executioner as the need for resources on a suffering world led to each major power on Earth launching their entire stockpiles of nuclear weapons at each other, nearly wiping the face of the planet clean of life. Those on the surface that survived were changed, left in a world charred by irradiated hellfires, forced to survive by any means necessary. And the animal life, once abundant and relatively benign, mutated into monstrous creatures from the stuff of nightmares.
However not all of humanity was doomed to annihilation by nuclear fire or the long, slow struggle of trying to survive the impossible. Buried, deep beneath ground, were a vast serious of Vaults: Massive bunkers where humanity could survive pure and unchanged, waiting for the day when the surface would finally prove habitable again. But these Vaults were not free for everyone, only those chosen by Vault-Tec Corporation were allowed to join. Many did, but many more perished, banging on the heavy Vault doors for a rescue that in many cases, never came. For this initiative, the Vault-Tec Corporation were seen as heroes.
Unbeknownst to nearly everyone, nearly all of the Vaults were built for much more sinister purposes. Vaults are designed to keep you safe from the ravages of the Great War that kill the world. But in truth, they are all part of a vast social experiment carried out by Vault-Tec Corporation and the United States government in secret.
In this Vault, Vault 63, hidden away in the forested expanse of northern New York state, carried a very special brand of Forced Evolutionary Virus, or FEV. Where in the future, FEV gives rise to the horrible scourge upon humanity known as the Super Mutants, but here, in this Vault, things are tuned just a little bit differently. Instead of changing you into a Super Mutant, instead the purpose of this experiment is to deal with seemingly spontaneous gender reassignment. Using the specially modified FEV and the air filtration system, all residents of the Vault will change into the opposite sex, sex organs, voice and all. The Vault's secrete research team have also made several items that could even speed the process up, becoming instantaneous.
To monitor the effects of the FEV strain on relationships between family members and peers without disruption, Vault 63 is set up with two sectors divided into specific gender: all males inhabit the western dorms and work on the power and industrial facilities, while the females inhabit the eastern dorm and are in charge of logistic, such as farming, cooking, teaching the children of the Vault. The two genders are only allowed to meet during the final meal of the day for three hours.
And the Overseer, the unquestionable tyrant ruling the Vault, knows more than what he is saying.
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First things first, what time period does this story take place in? Does it take place immediately after the bombs drop and sentence the entire planet to death by intense nuclear bombardment, or does this take place in the far off future or 2188? Or are you one of the very few who have been in the Vault since before the bombs dropped?