Seven years before the events that took place on Pandora with the vault hunters defeating The Destroyer, Handsome Jack, and The Warrior, there was a man who grew up alongside Jack, they we're the best of friends, but this young man, Jason, had a very serious problem, he was the direct descendant of one of the most powerful demons in existence, who's raw power exceeded that of all six sirens of the universe combined, but Jason however could not tap into his hidden power at will, there were moments when it released itself from it's confines and made him extremely powerful.
Leading up to the event's of the four Vault hunters, Roland, Lilith, Mordecai, and Brick, killing the Destroyer, there was a great betrayal.
It all started within Jack's wild life preservation, Jack gave Jason the title of Overseer of the preservation as they were so close throughout their entire lives, but there started to be odd occurrences every now and then, where a powerful creature would turn up in a bloody mess, inside their cages, with absolutely no evidence as to how it happens.
Jack decided to look into this, and tightened his security, and fitted four hundred extra specialist camera's in the wild life preserve, so that if it happened again, they would catch the footage.
One day, some footage from one of the camera's was brought to Jack by one of his many employees, it had shown Jason, walking from his office, then vanishing completely, when Jack confronted Jason about the footage, he simply stated that it was camera trickery, and Jack thought nothing of it.
Soon though, more footage had been caught, this time showing a whole lot more than anybody had expected, Jason was called into Jack's office, the tape had shown Jason, moving long distances in seconds, then phasing through the metal bars of one of the most dangerous badass creatures they had, then ripping it limb from limb with no effort at all, Jack had fear in his face, fear that Jason could do the exact same thing to him, if caught off guard, would he though? Could he do this to his friend?
Jack had no other choice, he knew that he could not kill Jason, he knew the demon was too powerful, instead they both agreed to send Jason to the other side of the planet to battle his demons, and try to harness the demonic essence in his blood and use it for things other than disemboweling creatures.
Jason did as he was asked, he traveled to the other side of the planet to some deserted badlands, to battle his inner demons.
Several years later, and approximately three years before the opening of the vault, the prison of te Destroyer, Jason had finished building a gigantic arch out of strange material found in a snowy pass that had been guarded by skeletal phantom warriors, none had attacked him however, as they had sensed his demonic blood, and let him go about his business instead of causing the extinction of their already dying race.
Jason had learnt over the years to use tiny fractions of his power at a time, but never enough to become anywhere near as strong as his demon ancestor, but Jason was able to utilize more of his power when around the strange rock that he had built his archway.
Jason already knew how we was going to battle his demons, he had built the archway with purpose, he was going to focus all of his energy to force his demonic side into a physical being and force the archway into a portal, a prison for his demon! Jason had never contemplated anything of this size before, or any conjuration, so there was no telling how it would end, weather it was going to work, or completely destroy Pandora, and he had to succeed, failure was not an option.
To succeed Jason had to build a well to store his power to call upon when he needed to create the Vault, and defeat his demon, the archway would be easy to turn into another dimension, it was just defeating his inner demon and imprisoning it which would take the hard work.
Jason created the portal ahead of time without much effort, and spent the next year meditating in the power well he had built out of the strange material, it was very effective and he found that his combat skills utilizing his power had progressed greatly, and he could call up a reasonable amount of power at his will.
It was time for Jason to finally face his demons, he went to the archway and opened it, he had also created a key, so that if the time came he could trap himself inside his prison with the demon and keep it from Pandora forever, no key, no how.
Jason knew that this could very well go completely wrong, Jack had picked up on this and had his last minute betrayal, Jack was going to destroy that side of Pandora with Jason on it, he knew too well that the demon was too powerful to be contained within a Vault that a single man made, this is where Jason knew he had to act fast, he elevated himself in position of the well and forced all of his stored energy into his body channeling it through his mixed array of emotions, when Jacks moon base was nearly in position Jack sent one final message apologizing about hi betrayal, and Jason apologized for blowing up his moon base, Jack didn't understand what he had meant then suddenly, the moon base exploded in a bright purple explosion that must have been bigger than the moon itself.
Jason used almost all of his power to summon the demon, and he immediately regretted it, the power of this creature was immense, matching his own before he summoned it, he knew this as going to be rough, he immediately drew all of the power left in the well and pushed hard to force the demon into the vault, it was a tough stalemate, the power was immense, then out of nowhere the phantom warriors re-appeared, Jason thought to himself that things were about to get rough, when all they did was gently fly towards him in unison and more and more appeared, when there must have been nearly a thousand phantom warriors, they all started glowing in sync, and they turned to purple ash and flew towards him, and encircled him, suddenly he felt strong, the phantom warriors had unlocked his power barriers, he was the all-powerful warrior his demonic blood right had granted him, he was unstoppable, he gave out a huge blast that eradiated around him and scattered for miles incinerating anything around him, except the warrior, this would take a concentrated blast, he mustered some more of his energy and blew the warrior straight into the portal, destroying the arch in the process, he was finally free of his inner demons.
Jason now free of his demonic sub life, stayed on this side of Pandora, he thought it best if Jack assumed he died with the warrior, and he helped the people of Pandora, and protected them from Jack's evil plans, until the day that four Vault hunters showed up in his town, he watched them grow from green mercenaries, to badass warriors, he watched them go through betrayal, and succession, he watched silently as his demon was released from it's prison, he let this happen no longer afraid to confront it should the need arise, but he would not always be here to protect Pandora, he watched the four vault hunters fend off his demon, whilst it could not be killed, it could be sent back to the vault until the next time it opens, he left them messages, and information, he passed it down to them, and they passed it down to the next four vault hunters to come to Pandora.
To this day Jason can be seen guarding his vault from high above the skies of Pandora, secretly watching incase the Destroyer of Worlds, re-appears.