The Yeti are an extremely pragmatic and semi-nomadic people. They are organized by familial clans who range across ancestral territory, primarily across a single peak with several camps scattered across. Because they are carnivorous, they have no real use for farming or gathering, making their culture centered around hunting. In some ways, they are fairly progressive because of this, seeing no gender barriers so long as one is skilled enough to provide for their clan. Though they live on the mountains, they often wander onto the flat wastes to hunt the massive creatures that dwell there. Almost all the items they trade are derived, in some way, from their hunting pursuits.

Among the major items they most often trade are treated leather, blubber used to create lamp oil, vellum, and ivory. Of particular note is the ivory since it serves them as both weapon and armor in addition to their extremely skilled craftswork at scrimshaw which is as often decorating their weapon as it is on jewelry and bauble. One of the items that a yeti will very readily trade for is Fish, a delicacy that they cannot get enough of, particularly given how rare it is to get it on their mountains. The last item that they are seen commonly traded has given them a rather grim and undeserved reputation.

The pelts of their dead. That alone causes quite a bit of pause, but the truth behind it is far more alarming to those who do not know their culture. The yeti are cannibals. Rather than let their bodies go to waste, they skin the corpse and prepare the meat. It is a simple practice, born of pragmatism, but nevertheless it has caused other cultures to demonize them. Despite all this, and the rumors that they kill their own, it is false. So long as they did not die of disease, it is a great honor to feed your clan of your own body. The pelts are used for trade simply because the Yeti rarely need any more fur on their bodies. Because of their fur the yeti have a very loose... almost nonexistent idea of modesty. The only time they ever wear something over their fur is when they wear their battle armor, which is a rightfully disturbing sight, so much so that the phrase "An armored yeti" is slang for trouble is about to happen.

Their beliefs are most commonly tied to animism, with at least one shaman in every clan, if not several. Their strongest belief is tied to the Aurora. They believe it is the spirits of their ancestors, and when they die, they will become part of it as well. One day, when enough of their kind have joined the Aurora, the world will know uninterrupted warmth.

Once, long ago, a lone man wandered the flat wastes. He knew he was going to die, felt it deep in his bones. To become lost in the wastes was just as sure a death as anything, but the biting winds and frozen chill gnawed at him as surely as the emptiness of his stomach. He could hardly feel anything except the pain and despair. The one small blessing was that he would be dead long before he could starve to death. The storms raged and he found the courage to hope, to continue to tread on for some miracle to save him, to find some shelter or an angel to shepherd him to safety. From the blinding storm, the thick curtain of swirling ice, a figure strode towards him and his heart swelled.

It was not the miracle he dreamt of.

The demon before him seemed unconcerned with the biting chill, the horrible winds, but he showed an interest in this lone lost traveler. The man collapsed, wishing only that his end would come quickly from the blizzard rather than at the hands of the demon. The demon, for his part, knelt before the man, knowing he'd given up. In an unheard of act of generosity, the demon comforted the man, patting him gently on the shoulder and the man jumped, his eyes drawn to the demon's face.

"Your suffering is like a fine ale to me, young mortal, but I find it too heady a brew for my tastes. I will give you a gift, anything you ask of me since you have fed me so well already." The demon did not move, just held out his hand so that the traveler could take it. Slowly, hesitantly, he reached up, believing the demon only to lie but having no other hope to his name.

"I-I don't want to die. Please help me." the wanderer said, taking the larger hand, the gray claws closing over his fingers. The demon pulled him up to his feet and a terrible grin split the demon's lips, showing sharp teeth the man would never forget.

"Done!" And just like that the demon was gone. Vanished like he had never been, leaving the man alone again in the biting gale. The traveller wailed into the winds and sobbed, unsure if any of that had truly occurred or had been a fantasy conjured by his tortured mind. Teeth chattering, he hunched himself and continued on, gathering the tatters of his hope about his frozen body.

He walked for so long, he could not remember how long, and worryingly he realized he had long since stopped feeling the cold. All he knew was pain, and more and more, hunger. As he plodded on, he found it harder and harder to move, and abruptly a pain in his chest brought him to his knees, and at last he collapsed, the throbbing in his chest abruptly ceasing, but the pain continuing on. He woke later, though he knew not how long. The storm was gone and so was the cold. An unbroken world of unspoiled powder stretched out for as long as he could see, brilliant under the moons glitter. He was utterly alone except for the chill and quaking of his stomach, having grown from a mere rumble into a consuming need. It hurt so badly that he could hardly think, but he came to his feet and ran, as best he could, hoping he might find something, anything that might save him.

He ran and ran, and up in the sky, the first stirring of the Aurora came, the ribbons of scintillating light streaking across the sky, its warmth leaking down. As soon as the ambiance hit him though, he felt as if he were on fire, screaming as the warmth bit down into his body far more horribly than the chill. He crawled beneath the ice, seeking shelter from that oppressive heat, and buried there under the white expanse he realized he could not hear his own heartbeat. In that moment, in despair, he knew the demon had been real.

He wandered for weeks, hiding under the snow whenever the aurora was in the sky, his only company the ever present, maddening hunger in his stomach. At last, he found something he thought he would never see again. A castle standing tall in the vale of a mountain. It was ancient, he knew not how ancient, but it was just as surely lost to the ages as he was lost in the wastes. The hunger drove him, hoping he might find something, anything, that could take its horrible weight away. He found it so hard to think, he hammered on with near animal instinct.

At last he came to the castle doors, hanging limp off the gates. In the darkness, he pressed forward, and at last came to a pantry. He found within, food that was barely edible, but it would seem as ambrosia to the terrible ache within. As he shoved it into his mouth, he found no respite. It was as dust to his body, and did nothing to take away the consuming hunger. He cried then, falling to the floor, but as he lay there weeping, he... felt something. A warmth somewhere in the castle. His stomach grumbled, and by some instinct, he was driven to find that warmth. Inside the castle, to his surprise, he found a mountain lion and with unearthly strength he attacked it. Intent utterly on sating himself. The cat fought back, caught by surprise, but it was no match for the man's inexplicable strength. As it fell, the man tore in, the sweet warmth flowing over him as he shoved handfuls of meat into his mouth... but strangely it was the blood that seeped through his bones, that brought relief to him and brought the terrible, maddening hunger to nadir. He collapsed, asleep in the corpse of the lion once he had drained it completely.

He awoke with the return of the hunger, enraged at having been quelled, and no matter how much meat he tried to eat of the frozen body, nothing satisfied him. He went wandering the castle again, manic and shaking, and it was then that he came across a mirror and saw the ruin the storm had made of his face. He was horrified and smashed the mirror, unable to bear his monstrous visage. At last, he gave up all hope, knowing he lived a cursed existence.

And in that moment the demon returned, grinning as he had when the man had named the demon's gift. He had grown fat, it seemed, for following the man. His weight jiggled as he paced around the morose figure, his claws stroking his girth merrily.

"What ever could be the matter my friend? Did I not do exactly as you asked? You have not died, just as you requested. It is a shame you did not ask to keep living, but I have lived up to my end of the bargain." He cackled maliciously and knelt over the prone, cursed figure. It turns out, as it were, that was a mistake.

Enraged and utterly gripped by his hunger, the man leapt upon the besot demon. So surprised it was, that he did nothing as the man ripped into his throat with his teeth. The ichor that flowed from the wound was delicious, soothing all the woes and at last putting that terrible companion, the hunger, to rest. As he drank from the fiend, his mind slowly returned, the last dregs restored by the sweet taste of the demonic blood. He could not remember much, nothing of his life before the plain of ice, but he at last felt at peace... but as he collapsed, falling quickly into unconsciousness, that hunger was replaced by a thirst of a different sort. Whatever the demon's blood had done to satisfy him, it had passed upon a demon's thirst.

A thirst for power.

So, a demon is what made the first vampire, but as he discovered, the only thing that could satisfy his hunger was the demon's blood.
Those vampires who consume demon's blood will never feel their thirst again, but will be driven to sire and accumulate more and more power by still drinking blood.
Those poor sonsabitches who don't manage to snack on a demon eventually lose their minds and become feral, which makes up most of the vampiric population on the wastes, these feral roaming beasts.
The ones who achieve that... equilibrium, I guess, are known as Nocturni.