Chapter 1: A Divergent Ending
Two figures stood amidst the ruined courtyard of Ryuudou Temple.
One was a man with golden hair and scarlet-red eyes. He was missing an arm and a giant gash ran across his torso, going from his clavicle all the way down to his hip. His face was conventionally handsome, but at the moment, it was twisted into an ugly scowl. The man glowered at his opposition, his chest heaving, both from exertion and anger.
On the other side of the yard stood another man, a teenager on the cusps of adulthood. He had red hair and amber-colored eyes. The young man was on his knees, panting heavily. The mere act of breathing hurt. Compared to the other man, the red-haired teen appeared comparatively less roughed up, but that did not provide him any comfort.
Emiya Shirou glared up at his opponent.
He tried to will his body to move, but no matter how hard he tried, his body simply refused to listen. The usage of his reality marble had consumed nearly all of his prana. Even the energy that Rin had given him was all gone, used up in his battle with the King of Heroes. Shirou was essentially a fish in a barrel, exposed and completely defenseless. Unfortunately, his opponent knew this all too well.
"Running out of mana is a pathetic way to go." The golden-haired servant stated with a rumbling growl in his voice. Gilgamesh's words grated against his ears. "Victory is yours. Die with that satisfaction, Faker."
As the servant spoke, a golden square appeared beside his head. It was the familiar activation of Gilgamesh's Noble Phantasm, the Gate of Babylon. A conventional long sword poked out from the center of the shimmering square; its tip pointed directly at the red-haired teen.
Silence filled the air, as a rustling breeze swept through the temple ruins. Gilgamesh savored the moment. Meanwhile, Shirou couldn't help but think back to the events that had led him to this moment.
The Fifth Holy Grail War was just one mess after another for him.
Shirou's first introduction to the war was by way of a spear to the heart courtesy of Lancer. Fortunately, Rin happened upon his would-be corpse and saved his life. After that deadly encounter, Shirou basically stumbled his way through the rest of the War.
Despite repeated warnings from both Saber and Rin, Shirou continued to throw himself headfirst into danger, even trading blows with the other servants, such as Caster and Rider. Truth be told, Shirou lost count of how many times he nearly lost his life.
Forced by circumstance, Shirou inevitably grew stronger. He learned proper magecraft from Rin and swordsmanship from Saber. There were also the memories/experiences that he received from clashing with Archer. Despite his dislike for the red-clad servant, he would be the first to admit that it was his encounter with him that led to Shirou's biggest growth spurts.
So many things had happened and quite a number of secrets were revealed, from Illya being his sister to Sakura's whole mess of a situation involving the Matous. Even now, it made Shirou's insides burn at the thought of not being there for either of them sooner.
Finally, there was the corrupted Grail. That problem was pretty high on Shirou's list of 'things he needed to fix, lest the world burns in cursed hellfire'.
That particular mess started directly after his battle with Archer at the Einzbern mansion.
After discovering Archer's true identity and reconfirming his own ideals, Shirou defeated him. Unfortunately, he did not have time to celebrate as Gilgamesh suddenly attacked the mansion. The golden-haired servant easily killed Berserker and put Illya to sleep with one of his Noble Phantasms. Archer tried to fight him off, but after their battle, he was running on fumes.
Shirou had watched as his alternate timeline counterpart was ripped to shreds by a near-endless hail of Noble Phantasms. There was no faking that sort of gruesome death.
Truth be told, Shirou did not really know how they managed to escape. Saber had to knock him out, otherwise he would have thrown himself at Gilgamesh in an effort to save Illya. Shirou would later acknowledge that it was the smart decision to make, but that did not mean he was happy about it.
Either way, the conclusion to the war was to be decided by the final confrontation between Shirou's group and Gilgamesh's group.
Their side consisted of Rider, Saber, Sakura, Rin and Shirou. The opposing side consisted of Gilgamesh, Kotomine, and the remaining servants, which consisted of Lancer and True Assassin. Lancer had survived this long mainly because Kotomine refused to let him fight, while True Assassin was procured by Gilgamesh from Matou Zouken's corpse through unknown means.
The girls were tasked with stopping the Greater Grail from descending, and freeing Illya from whatever fleshy prison she was held in. They would no doubt face resistance from Kotomine and the other two servants. Meanwhile, Shirou was responsible for handling Gilgamesh, a task that he himself had volunteered for.
While Shirou's situation was a little bit precarious right now, he could at least comfort himself with the fact that the girls had succeeded. After all, the sky was no longer the mixture of malicious reds and ugly purples that was present just a scant few hours ago.
He could see the warm morning twilight peeking out from over the horizon. That alone told him plenty. The lesser grail had been destroyed and its connection to the greater grail was prematurely severed.
All in all, they did pretty well for themselves. The only loose end left was Gilgamesh. Unfortunately, it wasn't looking too good for Shirou.
Amidst the silence and impending death, something suddenly happened. A distortion in space, an anomaly in reality, he didn't know how exactly to describe it, but whatever it was, it made Shirou's instincts flare up like crazy.
Before he could even think about doing anything, a black orb blinked into existence. It appeared directly where Gilgamesh's severed arm would have been. Dark miasma flared out from the orb like a raging inferno.
"What!?" Gilgamesh instinctively gripped his shoulder as he glared at the orb with a look that could practically kill. "Swallowing me accomplishes nothing!"
Shirou watched in equal parts awe and fear as the orb suddenly expanded, swallowing up everything within a five-meter radius, Gilgamesh included. The orb did not stop there. Winds buffeted all around Ryuudou Temple. The orb's gravitational pull suddenly increased, threatening to drag anything and everything that wasn't nailed to the ground towards its inky darkness.
"A hole left behind by the grail?"
Shirou's question went unanswered as a golden chain shot out from the blackhole and wrapped around Shirou's arm. The red-haired teenager was caught off guard and almost lost his footing.
"That malformed abomination!" A shout came from somewhere near the hole. "Does it not know that a fellow servant cannot be made its core?"
"Damn it! Are you trying to take me with you?" Shirou shouted back as he struggled against the golden chain's hold.
"Fool! I haven't the least intention of dying! Stay where you are, mongrel! At least until I climb back to where you are!"
Shirou gritted his teeth. Gilgamesh was too much of a threat to let free. "As if I'll let you! This ends now, even if I have to rip off my own arm!"
The magus was fully prepared to do just that, but before he could go through with it, another chain shot out from the darkness. It blurred past him and wrapped itself around a large tree located a dozen or so meters away from the main courtyard.
"Hmph! Do what you want! I no longer need you!" Gilgamesh gloated as he dispersed the chain around Shirou's arm. The golden-haired servant began the pain-staking task of pulling himself out from the Grail's hold.
Shirou narrowed his eyes. His facial expression morphed into one of determination "Like I said, this ends now!"
He stopped resisting the Grail's pull and allowed it to drag him forward. In fact, Shirou went a step further and kicked off the ground, propelling himself towards the inky darkness. Using the last remaining dregs of his prana, Shirou projected a familiar white blade.
In an instant, Shirou closed the distance. Before Gilgamesh could react, Shirou was upon him, sword already in mid-swing. What happened next was a mirror image of what he did back in his reality marble. Gilgamesh's remaining arm was lobbed off by Bakuya's bladed edge.
The golden-haired servant's face twisted into rage and disbelief as his body was quickly pulled back into the hole.
Shirou tried to stall his momentum by stabbing Bakuya into the ground. Unfortunately, the Grail's pull was too strong. The ground beneath his feet splintered. Shirou lost his only foothold. Any further resistance proved futile as he was quickly dragged into the hole.
I'm sorry everyone… I'm sorry Saber, I guess I won't be coming back after all.
Shirou inwardly muttered a small apology to the girls before everything went dark.
Gilgamesh's thoughts were consumed with rage.
He was angry at the humans of this era, for they had long since lost their way and were thus unfit to be ruled by him. He was angry at the Grail for trying to use him as its core. He was even angry at Kotomine, who had obviously failed at stopping the other party from destroying the lesser Grail.
Then, there was the mongrel.
He was livid, furious, outraged. No, words could not even begin to describe how angry he was at that counterfeiter. The mongrel had destroyed his treasures, which in itself was a crime punishable by death. The mongrel had also made a mockery of his authority through those disgusting fakes of his. Lastly, the mongrel had the gall to cut off both his arms, which was honestly his main gripe at the current moment.
If it wasn't for that Faker, then he wouldn't be stuck in this mess in the first place.
Unfortunately, it was already too late for what-ifs.
The Grail's vile curse was beginning to dig its way into his body. He could feel it corrupting him, eroding both his material form and his spiritual form. Soon, it would reach his saint graph and even that too would be lost within the Grail's tar-like sea of curses.
In the past, he had been able to resist the Grail's corruptive nature, but this situation was different. He was inside the Grail, where its curses were most potent. Eventually, the grail would wear him down. It would wear him down faster than he could think of a way to escape. Maybe, if he had more time, maybe then he could think of a way to escape, but…
Even as he was thinking such things, his physical body had long since lost the fight against the Grail's corruptive energy.
Now as a solely spiritual being, he knew he could not survive very long. Being so close to such a malignant force, king or not, would eventually destroy him.
But, as a king, there was no such thing as hopeless.
He did not have a lot of options, but if he could get another physical body and use it as a buffer, then maybe he could find a way out of this mess.
"Damn it! If this is what it will take then so be it! I refuse to be swallowed up by this abomination!"
There truly was only one way for him to survive.
Gilgamesh's gaze moved towards the Faker's body. It was floating aimlessly amidst the darkness of the Grail's inner core.
Like Gilgamesh, the Faker would also die. A normal human, Magus or not, stood no chance against the Grail's myriad curses.
Gilgamesh did not really care for the Faker's fate. In fact, he actually thought death was not enough of a punishment for the Faker's crimes. Still, despite how much he loathed to admit it, the Faker might be his only ticket out of here.
It wasn't much of a plan, but it was certainly a start. If he could just get his hands on the Faker's body, then he might actually be able to do something about this situation.
The first step was to possess the body, usurp control of it away from the original soul, and use it as a tool to reincarnate himself back to life.
Normally, this sort of resurrection style would be difficult to pull off, at least not without the proper tools. Fortunately, the Grail's inner world worked in his favor. This place was weird; it was a mixture of imaginary and incorporeal. Anything and everything that entered this place would acquire traits that made them both imaginary and incorporeal. Basically, right now, the Faker's body was stuck in a metaphysical state that could be likened to pseudo-mana.
The conditions were quite ideal for what Gilgamesh planned to do.
The process would undoubtedly be painful. Not for him, of course, but for the mongrel. Rather than a drawback, he viewed that as a good thing. It brought him joy to think that the Faker's last moments would be filled with nothing but agony. It was truly a punishment befitting of that fool.
Gilgamesh did not even realize that the Grail's corruption had already started to affect his psyche. Even if he knew, he probably wouldn't have cared.
A vindictive smirk stretched his lips.
It was time to begin.
Shirou screamed a soundless scream as he felt something stab into his skull.
The pain was so immense that it practically wrenched him back into the waking world.
Even with only an incomplete awareness of his surroundings, Shirou somehow knew that Gilgamesh was the one responsible for the pain.
The Grail's imaginary spatial properties allowed such things as thoughts and intentions to flow freely from person to person. That was how he realized that the bastard was trying to take over his body.
"L-like… like I'll let you…" Shirou muttered through gritted teeth as he cracked his eyes open.
He was floating amidst blackness. Gilgamesh stood in front of him, at a distance he could not properly discern. Shirou seriously hated him, probably more than he hated Archer. Still, he noticed something was wrong.
For some reason, the golden-haired servant was semi-transparent. His body was also crumbling away, changing into motes of golden light. It started with his extremities, but quickly moved up towards his face and torso. Shirou would have probably cared more, but he had other things to worry about.
The golden light flowed directly into his body through his eyes, ears, nose, and mouth.
Pain flooded his senses. It burned. It burned just as hot as the fires from his past, yet these flames were not external. They came from within him, a burning of the soul. Again, Shirou somehow knew what was happening.
Even before Gilgamesh began the take-over process, a portion of his spiritual body had been already destroyed by the Grail's curses. Gilgamesh wasn't just trying to take over his body, he was also doing something else with Shirou's soul as well. He was using Shirou's soul as a way to make up for the parts that he had lost. The process was kind of similar to a skin graft.
By the end of the 'procedure', Shirou's soul would either have more holes in it than swiss cheese, or he would be completely assimilated by Gilgamesh's own soul.
Neither was an option he was particularly fond of.
He struggled against Gilgamesh every step of the way. What the Golden-haired servant failed to acknowledge was that the take-over wasn't just a one-sided ordeal. It was a struggle between two opposing parties; a battle of wills. The loser would get his soul absorbed by the other. It was basically a spiritual cage match: two souls came in, but only one came out.
To top it all off, Gilgamesh's possession attempt was not the only thing that Shirou needed to worry about.
With the last of Gilgamesh's spiritual body either destroyed by the curses or converted into golden light, the Grail now needed a new target. Naturally, it picked the only other person here.
The tar-like mud surged towards him. Despite its liquid appearance, the curse burned like fire. The resulting pain unearthed unpleasant memories from his time in the Fuyuki Fire.
Shirou would have screamed, but even that was difficult to do.
The curse was trying to drown him. It was trying to drown both him and Gilgamesh. Unfortunately, Gilgamesh was a bit preoccupied right now. That left Shirou to deal with the Grail's myriad curses all by himself.
Shirou stood no chance against such a malignant force. He was drowning. He could feel himself slipping. Every cell in his body cried out in agony, begging for help, praying for salvation, and… to his surprise, someone responded.
Bright golden light bubbled up from his chest. The light spread all throughout his body, encasing him in a warm, familiar embrace.
The commotion even drew in the golden-haired servant, who briefly stopped what he was doing in order to watch the whole thing. From within Shirou's soul, he could feel the arrogant king's surprise. Shirou decided to worry about him later. He shifted his focus back to what was happening before him.
Slowly, the light formed a shape. It was a sheathe. A blue and gold sheathe materialized a mere foot away from Shirou's burning body.
Artoria's hallowed scabbard.
The Everdistant Utopia.
Avalon.
The sheathe had reacted, both to the curse and to him. Saber was not here with him, yet Avalon's full might had activated. It was a phenomenon that would normally never happen, yet here it was. A fully awakened Avalon shielded him against the myriad curses.
Suddenly, memories flooded his mind. They were of the moments he had spent with his servant and of the moments without. Saber, Artoria, the girl with the appetite to rival fifty men. He saw Artoria, both her past as King and the present that he shared with her.
Avalon was reacting to Shirou's earnest memories. The golden sheathe had acknowledged him as a pseudo inheritor, someone worthy of its protection.
When the corrupted magical energy touched the dome of light that encircled Shirou, the curses wreathed like thrashing snakes. The light did not actually stop the magical energy. Instead, it cleansed it, for Avalon was a sheathe meant to keep out all filth from touching its domain.
The curses were purged, converted into pure untainted magical energy.
With nowhere else to go, the energy naturally flowed towards Shirou's body.
Of course, this caused yet another problem.
The energy within the Grail was dense, so much so that its quality far surpassed even the mana found within the Age of Gods.
Even if it was only the small amounts that Avalon had purified, it was still far too much for his body to handle. Be it in quantity or quality, his body was simply not capable of holding the magical energy that the grail had constantly saved up for over five Wars.
If he continued to take in all this energy, then his body would either pop like a balloon or he would die from mana poisoning. Whichever came first.
Shirou was pretty much stuck between a rock and a hard place.
Still, he refused to die here. In his dreary haze, Shirou's determination to live flared up.
He needed to live. To see Artoria once more, to continue his magecraft lessons with Rin, to finally be the big brother that Illya always wanted, to cook another meal with Sakura, to teach Rider what it meant to live a normal life, to achieve his dream of becoming a hero of justice… He had far too much to live for to simply give up now.
For the first time in a long time, Shirou actually cared whether or not he lived.
So, he began to think.
Shirou knew he needed to either redirect the mana elsewhere or become the type of container capable of holding the Grail's mana. The first option was out. The Grail's imaginary space was like an enclosed room with no ventilation, and the purified mana seemed averse to the rest of the Grail's corrupted energy. Basically, the mana had nowhere else to go but to him.
That left him with only one option: become the type of container capable of holding the Grail's mana. Now the only question was how.
Shirou searched through his memories, looking for anything that would be able to help him weather this storm. Unfortunately, Shirou was never much of a magus. Before Rin's lessons, the stuff that Shirou knew about magecraft was worth shit. At best, they could be considered mistakes.
To his misfortune, none of the stuff that Rin had taught him ever went over what to do in case of mana overload, and especially not at such large a scale. So instead, Shirou found his answer in the form of a 'mistake'.
Shirou focused inward. His body needed to be able to take in more mana, but there was only so much room in his circuits. In that case, the solution was actually simple: he needed more circuits. And if there was one thing that Shirou was familiar with, it was 'making' circuits.
The red-haired teenager began converting his nerves into magic circuits.
Normally, this would have killed him. It was one thing to convert a single nerve into a magic circuit, but to do it with your entire nervous system all in one go? That was nothing short of suicidal. Fortunately, he had Avalon here to keep him going. Artoria's sheathe held the ability to heal its wielder from any wound, even the self-inflicted ones.
Even as the sheathe painstakingly fought off the Grail's corruption, it also worked hard to heal him.
The process of converting his nerves into magic circuits was actually easier to do in here than out in the real world. It had something to do with the Grail's imaginary properties. He wasn't quite certain of the specifics, but it wasn't really something for him to worry about.
Regardless, the process itself was unbearably painful. The pain was far greater than what he underwent during his 'training'. Still, the pain wasn't entirely bad. It reminded him that he was still alive.
Also, it wasn't just Shirou who felt the pain.
"Wh-what are you doing, mongrel!?"
He could feel Gilgamesh thrashing around inside his head. Shirou did not deign him a response. Or rather, he was incapable of responding. The pain practically locked up his body. Even his mental processes came to a screeching halt thanks to the pain.
A part of him kind of hoped that the pain would force Gilgamesh out of his head. Unfortunately, Shirou had no such luck. In fact, they had passed the point of no return a long time ago.
The two were now essentially one person. That meant that their senses were now linked together, including pain. This was another thing that Gilgamesh had overlooked in his arrogance.
The pain that they felt was the same; the difference lay in how they reacted to the pain.
For Shirou, pain was a familiar companion. His whole life started with pain. It accompanied him everywhere he went. This whole War was one painful experience after another.
By comparison, Gilgamesh was a king. He was used to living a lavish life. He grew up pampered, adored by the people. While he wasn't unfamiliar with pain, the golden-haired king was not nearly as intimate with it as Shirou was.
That was why he reacted so badly to the sudden spike in pain.
As time continued to pass, memories began flashing through Shirou's mind.
He saw the Fuyuki fire; the origin of the being that would come to be known as Emiya Shirou. He watched as a younger him made that fateful promise to Kiritsugu; it was where his dream had truly begun. He even saw snippets of his would-be life as Archer; the inevitable outcome that his reckless path of self-destruction would eventually lead to.
And then there were the memories of the war. Every struggle, every brush with death, and every interaction with the girls. They were the memories that he made with them, with Saber.
It was a short life and there were plenty of things he would have liked to change but as of right now, Shirou could proudly say that he did not regret anything.
Just as the last of his memories came to an end, a new set of images began to play.
Shirou sat on a lavish throne room overlooking a majestic city. The crowd below celebrated. What they were celebrating he wasn't quite sure, but Shirou had a feeling that these types of celebrations were actually quite common.
The image changed. This time, he saw an androgenous figure with long green hair; a sense of longing welled up within his heart. The figure smiled in a way that reminded Shirou of how Kiritsugu had smiled back when he first met the man.
He walked beside the figure as the duo toured the city from the first vision. The streets were filled with smiling citizens. After a while, they came upon a market square. The square was adorned with a large assortment of vendors, while men and women danced to the music playing somewhere in the background. A part of Shirou's mind wondered what they were celebrating this time, but he quickly realized that they weren't celebrating anything at all; this was just what a regular day in the city looked like.
Once again, the image changed. It featured the same green-haired figure from before, but something was wrong. Blood dripped out from the corners of their lips. Shirou weakly clenched the figure's hand, yet to his horror, the hand was cold. Not just clammy or pale, but frigid. He could only watch in horror as the light within the green-haired figure's eyes slowly dimmed. An unquenching rage bubbled up from the pits of his very core.
These were not his memories… They were not his memories, yet the emotions that he felt, they were undoubtedly real.
"Do you understand now, mongrel?" A voice called out from within the depths of his mind. "My life was one befitting of a true King. The era that I lived in was one of prosperity and peace. The world's current era of humanity cannot even compare. In fact, they serve as nothing more than a stain upon the legacy that I have left behind. They are unworthy to inherit the Earth that I once trod upon!"
"The world must be wiped clean and I will be the one to see it through, with or without the Grail's assistance."
"Give up now! Take honor in the fact that your sacrifice will save my life."
Gilgamesh's words reverberated through his skull. As much as it annoyed him to admit, the blonde-haired bastard had truly lived a life worthy of a hero from legend. Still, Shirou refused to accept him. He could not simply brush aside all the evil that the man had committed throughout this war.
The being that had attacked him, the one that had taken Illya and attempted to use her as the grail's core, that was not the hero whose memories he had just watched. It was a pale, ugly imitation of a man that had once been acknowledged by the Throne of Heroes.
"I… refuse!" Shirou shouted back with as much strength as he could muster.
His defiance was met by a mental blow that left his mind reeling. Gilgamesh was obviously not pleased. Still, Shirou weathered through his rage. Shirou's own soul was forged by fire and steel. It would not bend to the whims of another man so easily, not even to a king.
As if sensing the shift within their battle, the surrounding space suddenly began to distort.
The magical energy within the Grail spiked. Tar-like mud surged from every direction. The intensity and amount far surpassed anything he had ever experienced before.
The corruption was too strong, the myriad of curses too plentiful.
Avalon by itself was not enough to protect him.
In his desperation, Shirou tried to imagine something that could help him fight back against the corruptive magical energy.
The only thing he could think of was Avalon.
It always went back to that single artifact. It was what had truly saved him from the Fire all those years go and it was what kept him alive throughout the War.
He could trust no other object but Avalon to keep him safe, so that's what he created. He attempted to project a copy of the hallowed scabbard.
Slowly but surely, a golden sheathe materialized directly before him.
The copy was nearly identical to the original, from its appearance all the way down to the warm aura that it emitted. Shirou's ability to project Avalon was based on his intimate history with both the sheathe and its owner. Without either one, it would have been impossible for him to recreate something crafted by inhuman hands.
He did not stop at just one either. In his haze, he projected another. And another and another and another. It would have normally been impossible for him to create so many high-level Noble Phantasms, but Shirou found a workaround by borrowing some of the Grail's magical energy. In total, Shirou projected twelve copies of Avalon.
Although the copies themselves were weaker than the original, individual strength wasn't really what he aimed for. Instead, he believed in the concept of "strength in numbers." And in this case, it actually worked.
Rather than acting independently from one another, the copies worked in tandem, amplifying their individual effects to a height far greater than what should have normally been possible. The sheathes formed an array of sorts, with the original serving as the core.
In the end, the 'Avalon protective network' proved strong enough to weather the flood of curses. Unfortunately, that also meant that the amount of purified magical energy had increased. Shirou had to adjust accordingly, increasing the rate at which he converted his nerves into magical circuits.
The chaotic struggle between Avalon, the Grail, and Gilgamesh continued for what felt like an eternity. The constant pain had somewhat dulled his sense of time. He honestly thought that the battle would continue on for another eternity when suddenly, it all just… stopped.
Floating amidst the empty void was a single figure.
The figure had unkempt red hair with a single streak of white. Glowing blue veins covered almost every surface of the figure's body. The color of their eyes rapidly fluctuated from silver to amber to red.
Naturally, the figure was Emiya Shirou. His body thrummed with power. It was the sum aggregate of the Grail's stored up magical energy, all condensed into a single human body.
Shirou had successfully converted every single one of his nerves into magic circuits. That was more than 7 trillion magic circuits. It was an incredible feat, achieved only through a combination of unique circumstances, convenient tools, and an ungodly amount of human determination.
Gilgamesh's incessant voice was also no longer rattling inside his head.
He won.
Unfortunately, Shirou was not out of the woodwork just yet.
The Grail's corruption was no more, all of it purified by Avalon's radiant light. Even the remnants of Angra Mainyu had been cleansed; not even a spec of the Avenger remained.
Without the corruption that had plagued it for nearly seventy years, the Grail now had enough magical energy to enact an actual miracle.
If it was only that, then Shirou's 7 trillion aggregate magic circuits would have been enough to store all the energy.
Unfortunately, what Shirou did not know was that the mana he was taking in wasn't just from the lesser grail. It went beyond that.
The girls did not actually destroy the lesser Grail in time. They had come a moment too late. They did not prevent the greater Grail from descending; they interrupted it.
By the time they got there, the lesser Grail had already established a connection with both the greater Grail and Akasha. Still, the connection was fragile, like a sliver of light amidst a darkened room. With the lesser Grail effectively destroyed, the connection would eventually vanish, closing the door on Akasha once more.
Still, the energy remained. So long as the connection existed, the greater Grail would continue to flood the real world with Prana supplied directly from Akasha itself. It would not stop until the connection fully disappeared. What's more, the remnants of the lesser Grail acted as a filter of sorts. It automatically converted Akasha's magical energy into curses.
This was what Shirou was actually taking in; a portion of Akasha's magical energy.
Akasha was the root of all magic. It went beyond the confines of the multiverse and existed on an omniversal scale. Even with 7 trillion nerves, Shirou's human body would not be enough to store such potent magical energy.
Avalon worked desperately to try and keep Shirou alive. Unfortunately, Avalon was a tool that healed. While it could heal the symptoms, it would not fix the underlying cause. It would only prolong Shirou's suffering.
Fortunately, it wasn't only Avalon that wanted to keep Shirou alive.
Now that the lesser Grail (or at least what remained of it) was purified, it could finally act out its original function. First and foremost, the Grail was a tool that responded to intention and desire. It was the ultimate wish-making device and right now, it was responding to Shirou's earnest desire to live.
While Avalon kept him alive, the lesser Grail modified his body into something that could hold a portion of Akasha's magical energy.
It began with modifying his new magic circuits. Shirou's original 27 circuits could barely handle 10 units of magical energy. The Grail made sure that his new 7 trillion circuits could handle more than that on an individual scale.
While these new circuits were nowhere near the level of something like Barthomeloi's Blue Blood Noble Magic Circuits, they were still superior to what the average Magus possessed, barring special exceptions like Tohsaka Rin. In essence, Shirou now possessed 7 trillion above average magic circuits.
The Grail's modification was an act similar to the first true magic, "Denial of Nothingness". Instead of creating something from nothing, it was permanently creating something great from something comparatively less so. In fact, the Grail took it a step further and actually connected Shirou's new 'nerve circuits' with his soul.
Lastly, the Grail also converted his brain into something that could be likened to a pseudo magic-core. It still acted and functioned as a brain, but it also had the secondary effect of generating magical energy. The rate at which it produced energy was comparable to the likes of Artoria's magic-core.
Avalon slowly sank back into Shirou's chest, while the twelve copies dissipated in particles of blue light. The glowing veins that danced on his skin slowly receded, while Shirou's eyes eventually settled on a familiar warm amber hue.
The Grail's modification was coming to an end. Shirou's body was now able to properly process the magical energy that circulated within the Grail space.
It was also at this time that the pain and fatigue finally caught up to him. With the last vestiges of Gilgamesh's consciousness sublimated into his own, Shirou no longer needed to keep fighting. He promptly passed out.
It was at this moment that the Grail too reached its limit.
After its physical body was destroyed, the imaginary space that constituted the Grail's remnant vestiges began dwindling by the second. The struggle between the Grail's myriad curses and Avalon's own aura only expediated the process. The imaginary space began to breakdown, cracks of blinding light forming all over the darkness like breaks in a glass cup.
Still, the Grail attempted to do one last thing. It might have saved Shirou's life, but it had yet to truly fulfill his wish.
It borrowed a fraction of Shirou's plentiful pool of mana and attempted to grant the winner's wish. Naturally, the winner of the War was Emiya Shirou.
Since Shirou did not actually make a wish, the Grail had to improvise. Instead, it sought out Shirou's greatest desire. After a few seconds of prodding his mind and memories, it came upon a singular word: Hero.
A dream passed down from father to son.
The impossible ideal of saving everyone without sacrificing anything.
Of a broken boy's earnest desire to be a hero of justice.
The Grail found it. The one and only wish that it would ever grant within its 200 years of existence.
Light continued to suffuse into the area, but this time, the light did not originate from the cracks that covered the imaginary space.
One… two… exactly three seconds passed before the entire area was swallowed up by blinding white.
After the light died down, nothing remained.
No Grail, no darkness, not even Emiya Shirou himself.
All of it vanished, with not a single trace left behind.
Author's Notes:
The route used for this story is heavily based on UBW but with some changes to better fit the narrative. These changes are told/hinted at in the chapter. This list is merely for clarification. Changes include:
1) Archer dies in the mansion
2) Illya and Rider live
3) Sakura gets saved part way through the War
4) Shirou does not officially enter a relationship with anyone but is closest with Saber