Eons ago, humans and Espers co-existed peacefully on the planet Gaia. Humans were naturally frail, puny and inferior creatures compared to the Espers, but they made up for it with their intelligence, ability of choice and technology. Espers, on the other hand, were beings that surpassed humans in every attribute. They were immortal creatures, with a vast knowledge of the world. They could wield magic, and they had their own unique abilities, ranging from elements of nature, to hazardous blasts of energy that obliterate nearly all foes.
Dispatched by Goddess Minerva, they were sent to monitor mankind, to keep humanity in check, so that they would not be tempted by the corrupted impulses that dwelled within them. Greed, malice, deceit, and many negative tendencies were notable examples. These majestic beasts also had another job “implanted” on them. That job was to keep humans away from the abstract known as “The Sinner” who wanted to influence the humans into awakening their impulses, so that chaos was ensured. As a result, with the efforts of the Espers, humanity remained pure, never falling into their sins.
The question is: Could the Espers achieve the same level of purity as the humanity they helped to attain? The answer was negative. It just happened that “The Sinner,” infuriated by not being able to influence humanity, targeted the protectors themselves instead. The Espers vainly tried to fight off this abomination but their powers were dwarfed by it. Eventually, the entity succeeded in overwhelming the ones who were engaging it, while most of them fled the scene upon the request of their brethrens, who sacrificed themselves to forestall it in order give them time to escape, and hide from it.
The moment “The Sinner” triumphed, it overtook the defeated Espers’ systems, rooting its “stain” into their souls, changing them into soulless killing machines that obeyed it’s every command, rather than influencing them into turning against their kind. As a result of the “stain” that was implanted, the emotions and the will of the Espers to fight back were nullified. Unfortunate Espers that had fallen victim to the “stain” were the most important ones, like Tiamat, Diablos and Cerberus. The remaining were disposed of as trash. They were either too weak to contain “the stain” or they were trying to warn the Espers in hiding of this event.
Having the important Espers in its disposal, “The Sinner” ordered them to slaughter every human and Esper who opposed him, starting with its greatest nemesis, the Espers. With the edict carried out, the Espers’ fortification of their stronghold barely withstood the might of their former comrades, due to the enhancements bestowed upon the dark Espers by their nihilistic master and the pure Espers’ reluctance to fight against their possessed brethrens. When the temporary refuge had fallen, they sought out humanity’s assistance to purge their comrades’ souls and drive back this menace to whence it came.
Mankind heard their pleas and were angered that this menace was threatening their protectors and caretakers. Indebted and thankful for the creatures’ protection against their sinful virtues in the past; they helped the Espers to accomplish their tribulations, similar to how the Espers helped them conquer their negative emotions. But first, the Espers wanted to free their brethrens from evil’s influence. Man and beast learned that the only possibility was through exercising the power of a relic known as the “Sacred Gem”, which can only be found underneath the sacred grounds, where it was buried. Luckily, the human’s residence was located there and evil would not be able to guarantee both groups’ defeat due to the land’s holy nature that repelled evil. The fact that the artefact was underneath mankind’s residence, made it easier and faster for the Espers to deliver their brethrens from “The Sinner”. Normally, it would take a long time to reach the relic, but with the might of both mankind and beast kin; all it took was just half a day.
After getting the “Sacred Gem”, they resurfaced and engaged the might of the great evil together. The moment the battle commenced, they converted the corrupted Espers by using the gem. “The Sinner” had never felt so disgraced. Not only was its plan for spreading chaos thwarted, but the fact that he lost his tools of destruction was the last straw. Darkness burst from its being, directed towards the group, in a desperate aim to crush them, hoping to kill two birds with one stone. However, the times of working together created strong bonds between Espers and humans, allowing them to persist against its onslaught. With renewed vigour, they overcame its pitiful attack, and drove “The Sinner” away from this world forever, never allowing this sadistic anomaly to influence their lives ever again. In the end, humans and Espers lived happily ever after.