Disclaimer: I don't own in any shape or form any fictional works from Type-Moon franchise.
Prologue
Shirou ran through the dark forest. He ran as fast as his twelve years old legs could carry him. Stumbling and tripping on roots and branches hidden in darkness, the moon provided no light, obscured by heavy clouds rushing through the night sky. His breath came in ragged gasps, and the sound of his blood rushing through his head was intensifying by the minute. His lungs burned, his legs ached, but he did not dare stop, for it would mean his death.
He looked behind him, searching but finding nothing, only dark woods, even when he knew something was there. He tripped, falling on his side, rolling across the dry forest undergrowth, a new set of bruises to his already impressive collection.
He cursed himself for daring to look back. He may not see anything, but his nose told him enough. A stench he had never felt before, pungent, rotten, and sweet. Like if someone left a decaying carcass in the open and drowned it in honey. Yet instinctively, he knew it was not normal. It was something supernatural. Magical. He rarely used it, but he could smell magical energy. His father once told him it was expected for a magus to develop some form of detecting magical energy. His happen to be his nose.
Shirou got up quickly and continued his mad rush. The smell was getting stronger now, closer, and Shirou tired more and more. He didn't know how much longer he would be able to run like this, but the alternative was death, he was sure. He regrated now that he focused his magical training on structural grasping instead of reinforcement. Being able to strengthen his body sounded way more helpful than understanding an object right now.
He was slowing, his body exhausting the last dregs of energy. There was only so long a child could run at full speed.
Will he die here? Killed by whatever beast was chasing him?
He would laugh if he had breath to spare. So much for being a hero. He will end up as just another missing case, insignificant among countless others. Remembered only by his guardian, Fuji-nee.
He just wanted to do something, anything.
His dream of becoming a Hero of Justice felt like an unreachable mountain, so far away he couldn't even see the foothills. His magecraft stalled. Since his father died half a year ago, he didn't make any progress. Day after day, he trained only to meet the same results. Failure after failure. He picked up a sword and asked Fuji-nee to teach him, only to fail at it too. Oh, she praised him and told him he was good for a twelve-year-old, but he knew her words were empty. By his age, she could fight adults as equals and win tournaments and competitions. He couldn't even compare.
So when he heard rumors of people disappearing in the local woods, he sneaked out late at night to investigate. He just wanted to look through the forest a little, maybe find someone, help them. To get a step closer to realizing his dream.
Instead, after wandering for an hour, a sense of impending doom washed over him, followed by a sickly-sweet smell of magic. He could tell something was watching him from the shadows, something hungry. He only caught a glimpse of a pair of glowing red eyes before he ran for his life.
Shirou stopped, panting, as he reached a small clearing, a round patch of low grass and dead leaves surrounded by a ring of looming trees, indecision gnawing at him. He was lost. He didn't know which way the town was. He resigned himself just to flee, hoping for the best, but his indecision was his undoing when something hit him from behind.
The force of the impact hurled him forward, driving the air out of his lungs. He crashed hard against the ground, pain flaring across his right side and arm. Fear and pain gripped him equally as he clutched at his wounds, blood flowing between his fingers. It hurt. It hurt badly. Through the tears, he saw the mangled remains of his right arm, broken and gouged, bone visible through the blood. His side fared no better.
"Well now," an amused voice reached, whimpering Shirou. "I can't actually have you run away, can I, boy?"
A tall man dressed in a fine suit emerged from the tree line, with glowing red eyes and a cruel smirk. But it wasn't him that filled Shirou with dread. A colossal beast growled from the man's side, shaped like a great black wolf but bulkier. It stood tall, reaching the man's chest at the shoulder, large like a bear, with sharp fangs and wicked long claws.
I must've been what gored him, Shirou thought through the pain. He tried getting away from the monster, crawling with his one good arm, leaving a crimson trail. His vision swam from blood loss and exhaustion, yet he forged on. He couldn't die. Not here. Not like this.
Unfortunately, Shirou's determination alone was not enough.
"As fun as this was, I don't have any more time to play with you, boy."
The words stilled Shirou just as he reached the center of the clearing. He turned his head to look at the man.
He held his arm to the sky, palm open, a burning orb growing above him. It grew until it was larger than the man himself, illuminating the dark surroundings. The flame's warm yellow light mixed with the moon's cold blue, slowly peaking from behind the clouds.
"Goodbye."
With that single word, the man casts his hand down, the fiery ball following suit, hurling itself straight at Shirou, leaving him no chance to react.
A small, surprisingly quiet explosion later, only a smoldering crater was left, illuminated by the full moon. Of the boy, not even ashes remained.
In most worlds, that would be it. But in a world filled with magic, decaying as it may be, sometimes more factors were at play than they would appear at first glance.
Coincidently, the child carried an artifact inside him, unaware that his father had placed it inside him to save his life long ago. A relic of great power, unrivaled in modern times. Avalon, The Everdistant Utopia. The scabbard of the legendary Excalibur, sharing the name with the birthplace of fairies. It held the power to completely shield its wielder from harm, shifting their physical form into the realm of the fae, and heal him from any wound. The child wasn't its wielder but still received a fraction of the benefit.
In another coincidence, the clearing the child ended up at had an interesting feature right in the center, overlooked by everyone present. A ring of mushrooms. A curious thing, rumored to be an entrance to the land of the fae. A folk tale, but sometimes they held a grain of truth, although it was ages since fairies last freely roamed the world.
Last coincidence. As the fire burned the child, the moon broke through the clouds, and its light shone at the forest for the first time that night: a minor thing, but even those held meaning.
And when enough coincidences stack together, a miracle occurs.
With the direct power inside the child's blood soaking into the ground, feeding the fungi ring, and the more subtle influence of the moon, a gateway opened. A portal connecting the land of man to the land of fairies. It existed for a fraction of a second, but it was enough. The child fell through. Normally, he would end up in Faery, home of the fairies, and maybe they would help him, heal his wounds, or perhaps they would devour him, body and soul. But with the scabbard of the Excalibur as another factor, something unusual happened.
Reality twisted, and space and time dissolved as a torrent of power answered the call of Avalon. It did what it was created to do. It healed the child, closing its wounds and soothing the horrible burns. But it was not enough. The child was dying. The scabbard's powers were magnified once a connection with Faery was established, but the child was not its wielder, the wounds too severe beforehand. Yet it was determined to enact its purpose. It reached deeper. The fairyland resided outside of time and space, ruled by laws unique to it, and as Avalon continued its efforts, keeping the child alive in the void between worlds, a paradox took place. Avalon connected … to itself. It reached through time and found itself from the far past. Its power doubled, healing the child rapidly, and simultaneously, the two scabbards pulled at each other. It didn't take long before the child appeared in the lands of Avalon. The child popped into existence seemingly from thin air, gently falling onto a field of flowers.
But it was not a good thing. Avalon was the innermost sanctum of Faery. The density of mana in the air was far too great for a human to survive there. The child's body started to break down again, held alive only by the power of two scabbards working together. It deteriorated only to be healed again in a vicious cycle. It would continue to do so for a long time if not for the existence of the paradox. Two scabbards existed at the same time when only one should. It tugged at the artifact inside the child, chipping and breaking it bit by bit, as its existence was foreign to the current time. Sensing it, the scabbard decided to utilize its powers to the fullest, resolute to at least fulfill its task before disappearing.
A pillar of golden light shot toward the sky, centered on the unconscious child as the scabbard cannibalized itself while sucking in vast amounts of mana from the environment. Long ago, it changed the child's soul to bring it back from the brink of death. Now it did the same with its body. Block by block, it rebuilds the child as it breaks down, reforging the connection between its soul and flesh, golden patterns crawling over its form before sinking in. It took seconds, and an eternity, before the golden glow faded, leaving behind a newborn fairy, with a soul of man—a unique existence created by a series of extraordinary coincidences.