Before The War
Born in the small Bavarian town of Kronach, Stanislaus Braun quickly made a name for himself as a brilliant scientist, conducting many celebrated astonishing experiments over the course of his long and varied career. However, the most famous of these were his theories on preserving and propagating life, which ultimately got the attention of both the US Military and Vault-Tec: the former briefly contracted Braun to provide new methods for sustaining humanity in the wake of a nuclear war; the latter offered him a job.
During his employment by Vault-Tec, Braun created the Garden Of Eden Creation Kit, a highly-advanced terraforming device that could be used to transform post-nuclear wastelands into fertile, purified landscapes - inadvertently creating one of the Fallout series' more prominent McGuffins in the process.
It was also during this time that the aging scientist was made a Director for Vault-Tec's Societal Preservation Program, allowing him an influential role in the creation of the infamous Vaults. Initially, he played a large role in planning the experiments assigned to the various Vaults; however, all this changed with the creation of Vault 112 and Braun's new assignment as Overseer. Over the course of the construction and preparation, Braun became less and less engaged with the concerns of the outside world, until he finally retreated into the role of Overseer for good. It is not known what Vault-Tec hoped hoped to learn from the experiments conducted in Vault 112, but given the fact that no experiments are registered in any of the local terminals, it is possible that Braun commissioned the entire Vault and all its contents as a retirement present for himself.
The last Vault constructed prior to the Great War, Vault 112 was equipped with a highly-sophisticated virtual reality simulator, all interfaced with the "Tranquility Loungers" in which the Vault's populace would stay: while the bodies of the inhabitants remained in suspended animation inside the loungers, their minds were interfaced with the simulator, allowing them to spend the duration of their stay in an almost infinite variety of settings, doing theoretically anything they pleased. Since the Vault itself was powered by geothermal energy and maintained by an army of specially-designed robobrain caretakers, the occupants would have been able continue life in this virtual heaven almost indefinitely.
However, Braun was not interested in allowing a virtual heaven; immediately enthralled by the idea of a virtual world in which he could indulge his sadistic fantasies, he quickly went about dismantling the mechanisms that would have allowed the other residents to control the simulation, to leave their loungers, or even remember who they were. Instead, as Overseer, he seized total administrative control over the simulation, ensuring that anyone unfortunate enough to be assigned to Vault 112 would find themselves condemned to unending torment under Braun's control. However, Braun was farsighted enough to recognize that even with so many possibilities for entertainment, he might eventually grow bored with immortality: so, he commissioned a special program from the US Military, designed to simulate a Chinese invasion of the simulation - bypassing the failsafes that protected the inhabitants and killing everyone connected to the simulator. To his eventually dismay, Braun found that the safety protocols still protected him as Overseer: the program would kill everyone else in the Vault, but leave him alive. Disappointed, he kept the program well-hidden within his auxiliary command terminal.
When the air raid sirens finally sounded, Stannislaus Braun was greeted by the new residents of Vault 112, who obligingly donned their jumpsuits and took their seats in the Tranquility Loungers - unwittingly dooming themselves to an eternity of virtual hell as Braun's playthings.
Toucan Lagoons and Slalom Chalets
The inhabitants of Vault 112 were to spend the next two hundred years being tortured by Braun in a wide variety of ways; though most of them remain unknown even now, Braun's privileges as Overseer allowed him alter himself, the virtual environment or the residents in any way he pleased, allowing him terrifying variety in tormenting his victims. One way or the other, a pattern began to emerge: Braun would virtually murder everyone in the simulation, bring them back to life and erase their memories of the event, allowing him to repeat the pattern as many times as he pleased, enjoying the fear and pain of his victims as they "died" over and over again. Eventually, he would get bored with one particular scenario and switch over to the next one. Like most of Braun's virtual atrocities, most of these scenarios remain unrecorded and unknown, though two survive as entries on the auxiliary terminal.
One of these scenarios was Toucan Lagoon, presumably involving a tropical island of some sort: while playing here, Braun deliberately removed anything that could make the residents feel comfortable or safe, and assaulted them from all sides with virtual dangers. He drew particular delight from watching Martha Simpson slowly wasting away from scurvy and listening to the agonized screams of Timmy Neusbaum as he was eaten alive by a mako shark - over and over again. After several years of this, Braun grew tired of the scenario and decided to take a skiing holiday in the Swiss Alps by subjecting his playthings to the scenario "Slalom Chalet." Once again, Braun subjected the victims to as much horror and pain as he possibly could, from avalanches to frostbite: his terminal entries from this time mention his joy at watching Mrs Dithers slip up and accidentally impale herself on a wrought-iron fence. In the end, Braun lost interest again and moved onto the next scenario in line - Tranquility Lane.
A 1950s suburban cul-de-sac, Tranquility Lane was Braun's favorite scenario: his playthings felt safe here, even at home, and perhaps for the first time since he'd started torturing them, Braun was able to exploit this false sense of security, making them even comfortable in the illusion of suburban life - then relishing the fear that resulted when the illusion was shattered.
At some point in the years leading up to the events of Fallout 3, Vault 112 received its first visitor in over two centuries: a scientist by the name of Horace Pinkerton was able to enter the vault and steal a component from one of the Tranquility Loungers, later to be used in rebuilding the android known as Harkness. Unknown to Pinkerton, this sabotage freed Mrs Dithers from the simulator's memory block: though she was still unable to escape or fight back, Braun was no longer able to erase or control her memories. Suddenly remembering that she was trapped in a virtual world, Dithers attempted to warn the other inhabitants of what happened. Braun responded by aging her into "Old Lady Dithers" and adjusting the memories of the other inhabitants so that they would dismiss her as senile and deluded.
Following his escape from Vault 101, James - father of the Lone Wanderer - tracked down Vault 112 during his quest to find a working G.E.C.K. Believing that a scientist of Braun's stature would be more than willing and capable of helping him, James took a seat in an unoccupied Tranquility Lounger in the hope of interviewing Braun personally.
He's still there when the Lone Wander discovers him.
In the still-maintained Vault 112, the Lone Wanderer discovers several "Tranquility Lounger" simulation pods and enters the simulation. Inside, they find the simulated world of pre-War Tranquility Lane, a monochromatic locale based off 1950s society. Within this simulation are others in their simulation pods, now designated as Tranquility Lane's residents. They are encouraged by one of the residents to talk to a little girl named Betty who hangs out in the center with a dog named "Doc".
Speaking with "Betty", she reveals that she is really the assumed form of Stanislaus Braun. Having control over the simulation, Betty/Braun asks that the Lone Wanderer fulfill four tasks that will amuse her/him. Among these tasks are making a local boy cry, breaking up the Rockwells' marriage through assorted means, murdering Mabel Henderson in a "creative" way, and dressing up as a clown-masked killer called The Pint-Sized Slasher to terrorize and kill the residents. Should the Lone Wanderer choose to do this, Braun/Betty will congratulate them for a good show, reveal that "Doc" was really James in another form, and allow the Lone Wanderer to leave the system. However, Braun will just bring the residents back to life after the Lone Wanderer has left, just as he had countless times before to further his twisted amusement.
Alternatively, the Lone Wanderer can also go to the Abandoned House and, by entering the code via tapping a set of objects to the first few notes of Tranquility Lane's theme, uncover the "Chinese Invasion" failsafe. By initiating this failsafe, simulations of Chinese soldiers murder the residents, save Braun/Betty, Doc and the Lone Wanderer, and thus free them forever from Braun's control. Braun/Betty criticizes the Lone Wanderer for trapping him/her alone in the simulation, perhaps forever, but still permits the Lone Wanderer and James to leave as he no longer has control over either.
PersonalityBraun is very egotistical and condescending, often quick to insult the Lone Wanderer such as when he reveals that "Doc" is James. After years within the simulation, Braun started loving the control he had over the other Vault 112 dwellers as Overseer and began torturing and killing them over and over, only to revive them and wipe their memories clean before repeating the process. His sadism increased as the years went on.
Braun is also quick to anger. If the Lone Wanderer should attack his Betty form, Braun summons a lightning bolt to kill the Lone Wanderer (even if the Lone Wanderer has activated the failsafe). He also expresses his anger (with a hint of fear) if the Lone Wanderer activates the failsafe, thus condemning him to being entrapped within the Tranquility Lane simulation.