When The Willow Tree Twisted

Prologue

Our world is completely frozen.
Not by an ice age, or global cooling, or climate change, as you might have thought. Those things don't bother us here. You see, our world is split in two overlapping layers, separated by what we call the Veil. The humans live on one layer, while the other is inhabited by the magical immortal beings - angels and elves mainly, but also spirits. A spirit without a host will choose a newborn angel or elf and merge with their mind and soul, becoming a part of them, and in most cases the child would be named after the spirit which came to inhabit them. Humans fear their more mystical neighbours, and the creatures of the magical realm aren't particularly fond of the humans either. Which is why the Veil only allow them to cross from one layer to the other if the gods permit it.
Keeping the peace in our world are the three lords. Three exceedingly powerful magical beings who have been around for almost as long as the world itself. For millennia, life was peaceful and just under their co-operative rule. But then something changed, and they started warring with each other. Much magical and human blood was spilled before they finally stopped fighting. But the damage had already been done. Bit by bit their hatred took over them, freezing their hearts and doing the same to the world around them, human and mystic realms alike.
Once every generation, the gods choose a newborn child and place upon him or her the fate that they should go through the Veil and attempt to finally end the hatred and the winter, to finally bring warmth into the barren, desolate world. Of course, of those chosen to embark on this mission, none have ever returned.
It was into this desperate, dying world, that a young boy was born, to parents past child-bearing age, who had prayed desperately, unsuccessfully for years to be granted this blessing. On the day of his birth, he was presented to the gods with the name Siren. On this day the gods placed upon him the terrible fate, that when he saw the willow tree twist he would be forced through the veil and made to try and bring about the end of the eternal winter.
In anguish his parents hid him away from the rest of the world, never letting him outside of their cottage, locking him away in his room in the hope that he would never see a willow tree, and that he would be safe and protected there.
And in this way Siren grew up for twenty long years.
But the gods always have a way of getting what they want...