Before the world was solid, forests and mountains rose and fell as empires do. Slowly, the land took form, and forests of all kinds took root. Before the Gate was made and the Lion guarded the realm, the West bled into the rest of the world - and on the borderlands stood a forest of aspen that whispered with the wind. Their dark eyes peered at strangers, and all warned that any who ventured there did not return.
The Boy Before Stars had heard these stories, but he rarely paid them mind. He would ride on the back of his favorite horse, called Altair. The horse had been made from lightning and thunder and the rich earth of the Orchard. Each fall of his hooves sounded like the sky splitting open and the ground crackled and split beneath him, but the Boy Before Stars adored him most of all the horses.
Altair was not an easy horse to ride. He required constant attention and focus, and even the slightest distraction to his rider would have him bucking. But just as the Boy adored the horse, the horse adored the boy. They rode perfectly, and the Boy Before Stars would often gallop and trot past the aspens to impress his friends (those who were so easily impressed).
One day, though, the aspens shook especially hard and their eyes became especially sharp, and from their maze of limbs came the Aspen, the spirit of their system, given shape and form by those it had watched all its life. The Boy rode past and caught glimpse of this spirit, but it hid, not wanting to be seen. So the Boy continued on, aware that the Thunderhorse had brayed a warning at him.
He returned the next and the next, and the spirit hid each time.
Until the day it did not.
The spirit was as pale as the aspens with eyes as dark as theirs, hair as green as their trembling leaves, limbs as wily and shaking as their branches. The Boy had never seen such a creature and gazed in awe, and he was so taken in by the sight of it that the horse bucked and thundered and threw him from its back. But the Boy continued to stare, captivated, at the spirit of the aspens. The spirit turned and walked deeper, and there was no hesitation as the Boy followed it in.
The aspens tugged and scraped at his skin, but he paid them no mind. The spirit led him deeper, and deeper, til all that could be heard was the rustling of the leaves and the creaking of the trees; til all that could be felt was the heavy unblinking eyes of the trees and the thudding of their power.
The spirit turned to him and captivated him with spells unknown to any creature before, and the Boy fell to him. It seemed, for a moment, there would be calm and joy.
The aspens reached forward with their trembling limbs (or were they branches?), wrapping around the Boy, and it was not until much later - what could have been a day or a decade - that he awoke, hanging from the trees, blood dripping slowly to the ground, feeding the aspens at the heart of their forest.
The spirit dug his fingers in deeper, and the Boy cried out as more blood poured from his chest. The aspens rattled, and they grew, and their white skin took on a deep pink hue as they drank. The Boy grew weaker, but he could not look away from the dark eyes of the spirit nor tear himself away from the piercing limbs. He would die, he knew now, as a sacrifice to the aspens.
When he was weakest and sure of death, though, thunder and light split the forest in two. The aspens shrieked and the spirit shrieked and the Boy cried out as he fell from the trap to the blood-stained ground. Fire lit every tree and hooves as loud as skyfall ripped into the forest, and it was so that the Thunderhorse came to rescue his rider.
The spirit stood as well as it could to the horse, but with one sharp kick it lit the spirit aflame. The Boy, bloody and frail and shaking, held fast to his friend, and with speed not since known, they escaped the forest and returned home.
And this, boys, is why you don't go wandering into the aspen forests alone.