This has been in the works for about a decade, never got around to finishing it off. But it came up in game a couple times recently, so here is a finished version, for players, of who “The Demon” was, and what went down in the world. I imagine, if this version exists in the game world, that it might exist in the great library, where everyone has a story that includes their whole lives, even into the future. And no one knows who the author(s) are.
Hiran, the strongest and most vile of the primal spirits, was worried. He had always been so powerful that he didn't believe anything could threaten him. During the Titanomachy, he saw titans and gods killing each other, but he knew he was stronger than any who had died. But then, Mother Terra was killed and everything changed. Not just because all of creation almost ended with her, not just because he and the other Hierarchs punished Ra for his part in it and forced the Titanomachy to end, not it was more than that. Terra was stronger than Hiran. She was the only entity in existence that he would admit this of. And if she could die, so to could he experience death.
Hiran, as one of the immortals with the greatest view of creation, knew a secret that only five other beings in all of creation knew: they didn't make creation, it already existed. Someone else must have made it. He usually buried this thought down deep and didn't contemplate it. But in the silence after everything was done, he knew that he had to. Because Hiran was terrified of death.
Hiran prayed, therefore. For the first time in his entire existence, Hiran acknowledged there was something greater than himself, and he prayed to whatever that might be. And something answered. Hiran asked to be unkillable, but he was told that, as the lord of entropy, he should know nothing that exists can exist forever. Even time will end. So Hiran tried to outsmart whatever it was. He asked to be impossible to kill by man or by beast, by mortal or immortal, by weapon or by tooth and claw, by night or by day, inside or outside of his dwelling, on land or in the sea, and many more combinations of such that he felt he had named everything. And he received back and answer that his wish had been granted. But still he feared death.
Hiran traveled to The Tree. He looked upon and and felt how its power was tied to everything in every world. How what remained of Mother flowed down into it and out through its roots into him. How anything that harmed that tree would harm itself and all of existence. And Hiran was jealous of this tree that didn't need to fear death.
Hiran gathered his most loyal and reliable servants. They weren't many. He told them that he had a plan inspired by The Tree, but that he needed the help of two of them in particular. The Lady of the Web, mistress of unpleasant fates and fulfiller of curses. She would loop their fate through The Tree and then to a portion of creation. And Rhodin, the master of forbidden knowledge would devise the ritual to make it happen. This would give them absolute control over the land, far more control than any of them had as primal spirits. If anyone harmed them, the world itself would suffer. To kill them would require destroying the land they were bonded to. And Hiran had the Lady bond his destiny to The entire Tree. So that finally, Hiran wouldn't have to fear death.
Hiran commanded Rhodin to craft words of power; but they were foul words, words that stained the air when uttered, and words that made even all-seeing Ixion turn his eye away. These were words that could not be spoken, for the sounds would unmake the voice that dared to utter them. And the Lady wove threads of doom through each of them, threads that gathered all the suffering and hurt of existence and many forms of torment and woe that extend beyond what is possible within creation; and she wove those threads full of Rhodin's unspeakable words. And Hiran began to see how soon he would be free from the fear of death.
Hiran taught the unspeakable words to druids who tended The Tree, and he handed them the Lady's webs. The druids wept, and Hiran saw it as weakness, they feared his power and what he would do to the world. But in their hearts the druids wept for other, nobler, reasons. And Hiran made the druids work the magic through The Tree, and they did. As they pulled on the Lady's threads all of the gods and titans and primordials screamed in agony. But no sound was heard for their screams were the screams of Rhodin's unutterable words. Then the druids moved the threads into place, and now only Hiran and his servants screamed, but these screams could be heard. The foulness of the Lady's threads seeped into the world through The Tree and is tore, and it pushed, and it crushed these primal spirits until they were rent from creation except each into their piece of the world. Eternally unified with all existence through Mother Terra's power, now each alone in their own pocket, unable to perceive anyone else, they screamed. Spirits of life and creation they became bound to a destiny so foul that light itself refused to touch them, and in its absence, they screamed. Immortal beings, singers of the song that birthed the first mortal souls they were twisted so foul that sound would never again come near them, and in the silence, they screamed. Primal entities whose soul was meant to shepherd the world to its fate, they bent and warped until their doom and the world's doom were of a single form, and the world was so horrified by this form that it would never again touch them. And the form they created was a form that screamed. Immortal beings beyond time, to whom past and future were as one, they held the word's future as one with their own, a future so loathsome that change would never again come to them, that time's arrow pointed only away from them, that they only had one moment timelessly eternally. And that moment was the moment that they screamed. And Hiran feared that this was death.
Hiran took for himself the whole world, and he felt all of his servants. They each had the world as he divided it up. And the world became as they were. The Lady of the Web's lands sank into a sick mire and darkened with sorrows and thoughts of doom. The Fire Lords land burned to dust an empty and endless hunger. Discord's land broke apart and rang out with a terrible noisome shaking. And Hiran took for himself all their lands as his own, and he felt all of the mortals and beasts. They had power, each a spark of The Tree, and he felt them all. To his Grey Priest he gave the command, "harvest the spark" and the Grey Priest devised ways to sacrifice the mortals. Each of Hiran's servants followed his lead and power flowed into them from the deaths, and through them to Hiran. But Hiran knew that he needed more if he was to have enough power to stop fearing death.
Hiran gathered all the mortals of the world and commanded them to rape the corpse of Mother Terra. To work the land such that it produced more food than it was wont to do. To carve her bones and pull out the stone and metal and with them to build permanent homes, like caves above ground. And mortals, who also fear death, did as great Hiran bade them and raised the first cities and crops. And the people grew to be many in the cities. And the Grey Priest sacrificed more and more. And Hiran feared there would never be enough that he would not fear death.
Hiran was not alone in this thought. The people also wondered if he would kill them all. They prayed to the titans to save them, but the titans had been driven away in the Titanomachy, and could not answer their prayers. They prayed to the gods to save them, but the gods had been driven away in the Titanomachy, and could not answer their prayers. They prayed to the primal spirits to save them, but the primal spirits had all been subjugated by Hiran, and could not answer their prayers. There was no one else for the people to pray to, Hiran could not be unthroned from his rule of all the world. And the people despaired, because they did not know that Hiran killed them because he feared death.
Hiran had one rival for power. Ancient Night saw the things that Ixion's light did not. And ancient Night had watched everything Hiran had done. Ancient Night had heard Hiran's prayer, She had heard the answer, She had watched as Hiran had conquered the world, She watched as Hiran told people to defile the corpse of Her beloved daughter Mother Terra, and now, She heard the prayers of the people. And Ancient Night decided that She would show Hiran why it was that even he needed to fear death.
Ancient Night took upon herself a form that was neither mortal nor immortal but Avatar. It was neither man nor beast, neither male nor female, and this great beast, called afterward The Werewolf, attacked Hiran at twilight, on the threshold of his door, holding him aloft--neither on the land, nor the sea--it split open his belly and strangled him with his own entrails, that are neither the tooth and claw of an animal nor the weapon of a person. And Ancient Night ensured that every other one of Hiran's impossible conditions was met. And as Hiran died, he heard a voice, a voice heard by no one else but Ancient Night. Not even The Wolf with his hands on Hiran heard it. The voice said to Hiran, "I told you brother entropy, I told you when you prayed to me, that nothing within creation can escape from death".