Of Gods and Man - Where Angels and Demons Tread Ch.1
Prior to their departure, the Entities created the Gods and the three Realms - The Realm of Light, The Realm of Dark, and The Realm of Shadows. These were metaphysical planes meant to stop souls from seeping into the endless void and to help refine them into raw essence to be recycled into new life. Ciel - Goddess of Life was to overlook the Realm of Light and Eos - Goddess of Death the Realm of Dark, with the Realm of Shadow meant as a waypoint between the two, and not intended to have a leader. They also created Angels and Demons as servitors, duty bound to follow the law of their ruler and meant to assist in refining souls.
The task of angels were simple - The purgation of earthly satisfaction and joy through the means of complete contentment. A soul filled with excitement, mirth, merriment, or any emotion was one that Essence was not ready to leave. Because of this, angels assisted the spirit with what they needed to see their joy to completion. This could be something like allowing them to spend as much time as they wanted with their deceased family that had not moved on, or helping them finish their greatest ballad and perform it before a group of also departed one final time. While it's easy to consider that no time would be enough for spending it with family and friends, working on passion products, or cherishing life a final time, eventually joy and mirth wear out and simply the desire to move on remains. Sometimes these chores could take a few days, other times a millennia...a soul would only lay to rest when it was complete and satisfied. For the Realm of Light, the soul would be asked if it was ready, and if so, a final embrace between the angel and the soul was given and peacefully the essence would break down and return into the aether to be used for new life.
Although Eos was the original ruler of the Realm of Dark, she found herself at odds with her duty to the world as well as to her plane. Death, unlike life, was a full time ordeal...Ensuring it was kept sacred, watching creatures carefully to find which one was ready to meet its end, offering succor to those in intense pain and the Realm of Dark, fueled by chaos and torment, was beginning to grow beyond her means to control. It was then that Eos was approached by Azox - God of Destruction, the foul deity finding this as an ideal time to grow his power and bring about the destruction of Ayn he so strongly desired.
Demons were expected to follow a similar purpose, but through different methods. Souls the flowed into the Realm of Dark did so due to a weight on their soul, generally guilt. A murderer, for example, would find their soul at unease and would fall to the depths, meant to be tortured and ruined until the soul was broken down and essence was refined. Unlike with the Realm of Light, souls were often not consulted if they were absolved, as it would be quite easy to simply say 'yes' at the first sign of torture and pain. Instead, when properly repented and completed, the soul would dissipate on its own and essence would be returned. Although it was possible for a good person to simply have weight on their conscious or a bad person to have a soul ease itself to the Realm of Light, these were anomalies. Also the realms did not concern themselves with issues of Good and Evil, despite their angelic or hellish appearance, and instead with simply refining souls for essence. Their aesthetics and methods were simply best suited for the job.
"Well well...It seems you've quite the conundrum on your hands. So many lives both above and below. Surely you could use some help~"The dark serpent spoke, slithering from the cold void behind Eos, her glassy stare fixated on Ayn, "Oh no. I couldn't impose. I will find a way..." "Impose? Hardly. Why, it would be a blessing to have something to do. I would hate to grow restless from boredom and wreck more havoc on the world." After all, it was his purpose to sew the seeds of destruction and evil. The Goddess of Death paused, as if to consider his offer, before replying, "Hm...I don't know if I could relinquish control over the Realm of Dark..." "Of course you could. No one said you have to be bound to the duty. Allow me...You deserve the rest." And so, with a gentle sigh, she submitted. With her power, she forfeit control over the Realm of Dark to Azox...The dark dragon bursting into sinister laughter as the ritual subsided. It was his now. The power over the demons down below. With this he could unleash ruination upon the world.
But Eos was nothing, if not crafty.The upkeep of a Realm was a heavy price to pay in essence and energy. Realms simply didn't just exist, and like a building needed upkeep, so too did these metaphysical planes of existence. Also ruling over demons and angels weren't easy...They had their own free will and were more like lightly domesticated wolves than pieces in chess. Eos had feigned her disinterest to further his interest, and when he found that his powers towards wanton destruction were not as strong, he stomped, roared, and shook his fists. Many believe earthquakes are Azox's rage. What's worse is increasing the pain, torture, and condemnation in the Realm of Dark only increased the time it took for souls to break apart, meaning he had to actually temper his efforts to maximize his gains. This would not do.
Yet not all participants were keen on entertaining this never ending strife...
If he was going to sew the seeds of evil he needed more essence. He had to seize control over all means, and so he set his sights on Ciel - Goddess of Life and the Realm of Light. His plan? Simple - To conquer both realms and funnel the essence from the souls into his terrifying form until he was strong enough to obliterate Ayn, and so he sent his forces across the Realm of Shadows and attacked. Angels and demons were unique in that when other creatures died, their essence was repurposed into new life in a sort of reincarnation, but the essence used for these divine beings would only be recycled into the same being. This meant that any angels or demons that died were only reset back to their plane to resume the fight, and thus began the Immortal War, a constant tug between forces of good and evil with no plans of ending.