Prologue: The Roon
It is said that most stories begin as simply over-exaggerated truths. These stories are then amplified through the ages as they are told by the listeners until there are hundreds of thousands of different versions of the same story, all linked by the grain of truth passed down from the original.
Across the entirety of the Four Nations, there are a vast array of stories about blue giants. In the Fire Nation they whisper about a clan of bloodless waterbenders: savages that have ice running through their veins instead of blood. In the Earth Kingdom, the blue giants are simply huge, shirtless muscular men living in the mountains because they are so strong that they don't need protection from the cold. The Water Tribes tell of a third tribe that embodies the ocean spirit, living in the high-mountains to reach for the moon: as the ocean does. The Air-Nomads, however, sing of fallen waterbenders who were banished into the mountains, unbalanced to forever only feel the pull of the moon and never the give of the ocean. Nobody in living memory had ever set eyes upon one, but these linked stories and legends had still persisted of these giant, blue beings.
They were called the Roon.
Seventeen years ago, they came from the depths of the mountains in the Northern Earth Kingdom enormous, bare-chested, blue giants. They destroyed the Northern Air Temple and anyone that dared to stand against them; any surviving Air Nomads retreated to warn the rest of the world about the army of monstrous Roon marching South through the Jin De Pass straight towards Ba Sing Se.
The wise Earth King and Avatar Roku called for the Four Nations to unite and fight the common enemy together. No matter how much the Avatar, the Air-Nomad delegate or the Earth King grovelled, the Fire Nation refused to send troops. Months later, on the windswept plain that was the doorstep of Ba Sing Se, the United Nations Army met the Roon. It was three-on-one and the United Nations had numbers on their side; their right flank was protected by Ba Sing Se's Great Wall, their left was protected by the Serpents Bay and the Roon would have to go either through Ba Sing Se walls or all the way around the outside and somehow cross the river that protected the United Armies rear with no water vessels. The United Army also had the advantage of being able to ship supplies and reinforcements across the safe side of the Serpents Pass from the Port of Ba Sing Se or Full Moon Bay. The Roon had no ships and neither could they swim, and the vicious Serpents kept them from waterbending across to the Serpents Pass.
However, for every Roon they brought down, four good men were lost. In their mountains, the Roon had so mastered the skill of ice-bending that not even a master waterbender could melt their deadly projectiles; fatal injuries only spurred the bare-chested giants into a berserker rage that nearly made them unstoppable until they died from their wounds; their black eyes froze the bravest of men in fear; their touch could freeze the sun itself.
The battle raged on for two-hundred days. The Northern Water Tribe was the first to stop sending reinforcements. The plain had long ago turned to mud with the melted ice, blood and earth alike. The United Armies had desperately sent ships across the deadly Serpents Bay to try and attack the Roon from their right flank, none had ever made it to the shore; the air-nomads and their sky bison were slaughtered in mid-air; the Earth King would not risk Roon getting through the outer wall to let a large enough force out from inside the wall; despite the United Army's advantageous positioning, the Roon Army was also tactfully situated. The United Army was losing.
But then, on the one-hundred and seventy-eighth day of battle, the Fire Nation sent in their army. The tide of the battle was once again in the air, anyone's for the taking. Thus and overly desperate plan was hatched.
On the two-hundredth day of battle, the United Armies rallied once more: two brave warriors boarded a force of heavy cavalry and firebenders onto specially designed Southern Water Tribe ships soaked in oil to turn away the vicious serpents in a desperate attempt to cross the bay and flank the Roon. It worked, the rancid smelling oil kept the Serpents from destroying their ships and the armored war beasts and firebenders appeared just as Avatar Roku and what was left of the United Army hit the front lines with everything they had. The Roon, having lived in the tumbled rocked and treacherous slopes of the icy North Mountains, had two weaknesses. They feared fire and the battle trained ostrich-horses, eel-hounds and rhino-lizards and could never have stood against such a surprise cavalry attack.
The battle had taken its toll on the Roon too and when the right flank of the Roon began to retreat, the Roon fighting in the front line faltered upon seeing plumes of fire and huge war beast attacking from both the front lines and the right. The Roon army fell back and the United Army pressed forwards until the Roon fled back into the narrow confines of the East Jin De Pass, back into the depths of the North Mountains from whence they came.
The Earth King had the East Jin De Pass, the only way (other than flying) across the Slash, the bottomless ravine at the foothills of the North Mountains, blocked off so no army could ever pass through again.
The United Armies had won the two-hundred-day battle at Ba Sing Se, but with great cost...
...
Sixteen-years later...
It was a still, crisp night when the blue giants came down from their mountains once again. The pale orb of the moon was encompassed by a glowing ring, forewarning a vicious start to Winter. The air was frigid: a footstep seemed to echo for leagues. In the small Earth Kingdom village of Xiao-Ji, not even a child dared disturb the night.
Suddenly, shrill and piercing, the first scream rolled down the foothills of the mountains: it was a terrible, drawn-out wail of agony that seemed to go on and on and on until it stopped too suddenly. A heavy nightmarish silence followed in the wake of that first terrible scream. Then a cacophony of distant screams, shouts and howls started.
In Xiao-Ji lights began to flicker on; terrified villagers began to spill into the empty moon-lit streets; staring wide-eyed towards the North Mountain Range that overshadowed their village even in the dark and wondering what was making those terrible noises?
"It's the mountain spirit!" cried Yan, the miller. "It's angry with us!"
"No! It's the souls that have become stuck in the Slash!" gasped Jeod, her eldest daughter clutching at her elbow.
The distant wails seemed to reach a crescendo and the frightened villagers could only listen helplessly.
"Mercy on their spirits," breathed the baker, Mila, through her hands.
"That's no spirit. It's the men from the watch post!" boomed the voice of the huge, muscular figure of Nell, the blacksmith, who had to stoop to fit through his door. "They're under attack!"
The dozen villagers all let out some sort of fearful sound at Nell's words; half of them gasped in shock and the other half let out little shrills of horror.
"But they're protecting us from the Roon ... " whispered Jeod's daughter fearfully as one by one the howls of the soldiers began to die off.
"Lao, take two ostrich-horses and ride for Ba Sing Se as fast as you can! You have to tell the King! Climb the city's great wall if you have to," commanded Nell.
The young-man, Lao, only hesitated for a moment before rushing to do as he was told.
"Mila, fetch your brother and send him to Hai-Chen, tell them what has happened." As Mila disappeared into her house, Nell turned to the others. "The rest of us will either stay and fight or pack up and go - the choice is yours but you must make it quickly, if the Roon are coming for us we don't have long."
As the village of Xiao-Ji scrambled to ready themselves, the frigid night hung silent.