Rin was jerked forward against her seat belt when Shirou slammed on the brakes. The car skidded to a stop right before slamming into an overturned police cruiser. The street was ruined, shattered asphalt and slabs of concrete jumbled up by the explosion. There were cars scattered around like toys and sparking electrical wires dancing away from splintered telephone poles. The nearby buildings had been partially demolished, caved outwards by the massive blast from its point of origin.
In stark contrast to the ruin surrounding it the squat building that hid Kotomine's laboratory stood pristine in the center of the blast wave.
Shirou was already on the street and pulling futilely at the door of the police car. It was pinned against a lamp post and jammed shut. A familiar mantle of power began radiating from his form and he smashed his fingers through the windshield and quickly tore the roof off with a backhanded motion. His features hardened as he checked the still figures of the officers.
"Dead." He said grimly.
Sirens blared in the distance and Rin's mind whirled. Even if they won what would happen? The explosion, the underground facility, there was too much to hide from the human authorities this time.
Rin nodded and held out her hand. He took it as they began quickly picking their way across the ruined street towards the building. There was a sudden flash of motion from the roof and Rin felt her eyes drawn upwards. It was only for a moment, a struggling form pushed far enough over to be visible from the street before being drawn back, but it was enough. Rin broke into a sprint towards the door of the building and Shirou easily matched her pace.
"There's someone on the roof. We need to get up there, now!" She said.
"No time for the stairs." He said. He bent even as he ran and swept Rin's legs out from under her, carrying her bridal style.
"Hold on to me!"
She felt a pulse of energy shoot through him and he crouched low. Rin's stomach bottomed out as he jumped, rocketing through the air like a cricket. Even as they landed she felt that same anxiety grip her. How much of his life was he spending on something so simple? They crashed onto a fire escape half way up the building and Shirou set her down with a quick peck on the back of her head.
"Lets's go!" He said over his shoulder, sprinting up the rickety metal fire escape stairs.
Despite her worries, despite her fear, Rin felt ready for anything as they crested the edge of the roof.
The scene that unfolded in front of them was a chaotic mishmash of violence and raw energy. The center of the roof was dominated by a massive piece of machinery invisible from the angle of the street. It had two massive and intricate pylons covered in wires and electronics that arced with electricity. Suspended between them over a large control panel was a slowly rotating set of concentric rings like a spinning gyroscope. They moved within and through each other, changing direction and picking up speed as they orbited.
The most distressing feature of the machine was its occupants. Each pylon was topped by a thick glass dome. Each dome was filled with some viscous liquid and suspended there were the captive forms of Ilya and Sakura. They were strangely dressed, twinned in their disparity. Ilya had been dressed in an intricate, diaphanous dress of flowing white and gold with a striking red stole. Atop her white hair, billowing through the fluid like a halo around her head, a spiky crown reached upwards. The white of the dress complimented her pale skin and milky hair while the red drew the eyes like a beacon. It would have been quite beautiful under different circumstances.
Sakura was a dark counterpoint. Her dress was simple and black, riven with thin red lines like veins forced into tortured symmetry and eerily measured precision. The black tendrils of corruption that Rin had seen when she called on her considerable powers marred her features, creeping upward from her neck line to spider across her cheek and down the backs of her hands. Both girls' faces were partially obscured by oxygen masks and their bodies were covered in electrodes and monitoring equipment that fed down into the pylons that held them.
Kotomine's dark form stood unconcerned, his back turned to the proceedings as he manipulated the control panel at the base of the device. At the sight of him Shirou's power blazed and Rin could feel righteous anger radiating from him like a furious bonfire.
Between them and their target a battle was raging. Berserker stood with his back to them, panting, his shoulders heaving. Blood dripped from some unspecified wound on his body but he ignored it. Across from him, between him and Kotomine stood Alpha. He was as horrific as ever, an amalgamated abomination of science and magic. The expression on the human half of his face was amusement and excitement, as if he saw the entire operation as nothing more than a game, a test of his prowess. In his hand he held an odd weapon like a truncated lance or a sword with a conical blade. Its surface was covered in runes that slithered against each other as three separate sections of the blade rotated slowly in opposite directions. The amount of grail energy that radiated from his body was terrifying. Not only was he an enhanced servant but hundreds of beings as powerful as Shirou were siphoning their life energy directly into him.
The ladder clattered noisily as Rin and Shirou leaped onto the roof. Kotomine and Berserker both turned. The former broke into a massive grin. The latter could only spare a short glance. But Rin saw despair in his eyes when he saw that they had followed him. His shoulders slumped as if in defeat.
"Aaaah. Haha. Welcome, Omega. Tohsaka. Welcome! You're just in time to be privy to a great event. A happening, a becoming. You see..." Kotomine began with every indication of launching into a long winded villainous monologue.
"Shut up!" Berserker snarled. He feinted left and then drove hard right, trying desperately to get around Alpha.
Alpha's amused smile broadened. He moved with breathtaking speed and lazily swung his odd sword at Berserker. There was a blast of primal energy and Berserker was thrown backwards, smashing into the roof near where Shirou and Rin stood. Blood leaked from his nose and mouth as he struggled up to his feet.
Shirou quickly knelt by his side and pulled him up.
"Look, we gotta work together to beat him. Flank him. He can't deal with both of us at once, right? You go left, I'll go..." He said.
"No!" Berserker snarled.
He threw Shirou back and pushed himself unsteadily to his feet.
"If you beat him...beating him isn't worth the cost. Just get her out of here. I'll handle this." He said. His words carried that grim finality that only entered his voice when he was deadly serious. His teeth clenched.
He took a step forward. Alpha frowned slightly. Rin's spirit sank. She knew what was coming.
There was a subtle gathering of grail energy that swirled around Berserker. Rin's lip trembled. Berserker's breath began coming in ragged gasps. His hands clenched spasmodically. His teeth clenched as the first impossibly powerful wave of grail energy washed over him. Rin shook her head helplessly. He was activating his mad enhancement.
This was what it all came down to. This was it, the final battle. A fully powered Berserker, with his glitched noble phantasm that shouldn't be physically possible. A servant reconstructed from his genes to be pure, unadulterated power; Alpha. They faced each other across the small arena that was the roof.
And yet...
Berserker was Shirou. The man that Rin loved. To see him that way, to see him become an animal and worse than an animal. To see the look of bestial, insane fury etched on his features. To see what he was, honorable, kind, relentlessly optimistic, become twisted by rage into a killing machine of ungodly proportions, Rin felt her heart break just a bit at the though.
She didn't know why she did it. It was a panic instinct at the thought of losing him. She knew with her rational mind that Berserker was their only slim hope of prevailing against Alpha.
But she threw out her hands and screamed.
"No! Don't do it!"
There was a sudden lance of pain as her final command seal, the last vestige of control she had as a master, disappeared. Berserker's transformation faltered and he whirled to look at her. What was that in his eyes? Gratitude? Love? Despair?
But he turned back to Alpha with gritted teeth. Her command compelled him to cease, to remain human, to forsake his anger. But he fought it. He fought the command that the woman he loved gave to him in order to save him. He fought it in order to save her.
Too late Rin realized what she had done.
Berserker's transformation continued but it was flawed, incomplete. Her command locked away the vast portion of his power. He would fight on anyway. That's what he did. What Shirou did. They would always fight for what was right no matter who or what stood in their way. But Rin realized with bitter clarity that all she had done was condemn them all. Without his full strength Berserker didn't stand a chance against Archer. With his flawed transformation there was no option but failure.
Alpha's frown righted itself into a sardonic smile as he realized what had happened. From the altar Kotomine's laugh echoed out over the blasted landscape. He cackled with sadistic glee, reveling in the utter and imminent defeat of the only force standing between him and world domination. He turned to the machine and pulled a massive, ominous looking lever.
Rin cried out and collapsed under the sudden assault of power. Grail energy in quantities that she had never seen before or even believed possible began to radiate from the machinery. The power overwhelmed her, threatened to drown her. Between Alpha, Berserker, and the machine the roof was such a hotspot of magical energy that her senses began to blur and fade under the overwhelming onslaught.
In the confinement cells Ilya and Sakura's eyes snapped open. Violent bubbles frothed through the suspension solution and their backs arched in unison, mouths open in wordless screams that could not be heard. A torrent of arcane energy so powerful that the monitoring instruments cracked and exploded flowed from their bodies into the swiftly rotating space contained by the rings. The rings themselves spun faster and faster, blurring into invisibility as they contained the growing kernel of energy.
Rin struggled with her own disbelief as she tried to fathom what was happening. She had detected grail energy before, every servant radiated it like sunlight. But the power that she detected flowing from Ilya was different. More pure. It wasn't just grail energy, filtered and manipulated and poured in the form of a long dead warrior. It was the pure unadulterated energy of the Grail itself. It was the Grail.
She sensed the same energy flowing from Sakura's body. No, it wasn't the same. It was tainted. Twisted. A dark shadow of the white Grail pulled from Ilya's body that matched its power with its own dark intensity. And in the unfathomable mechanisms of that device those two energies were merged. Combined. Feeding off and feeding each other in a hellish torrent of pure power. The Dark Grail and True Grail began to combine into something...else. More potent than the sum of its parts, like a fleck of matter shoved head first into anti matter. More powerful than the Grail, than the Grail and Dark Grail combined. The pure, primal, cosmic power of creation. All at the command of one man.
The horror and magnitude of Kotomine's plan struck Rin so hard that the breath left her body.
In front of her Alpha and Berserker's duel rocked the building. Alpha released blast after blast from his sword and yet Berserker kept attacking. His features weren't twisted in his unfathomable rage but his jaw was clenched like a man who knows he is about to die but has decided to face death on his feet. Their movements were so fast that when their fight spilled into the street it was hardly possible to follow them with the eyes. Everywhere they went a wave of collateral destruction followed.
Berserker seized Alpha by the throat and hurled him through a building. Alpha's counter attack destroyed everything within yards of where he was standing. Berserker roared and tried to grasp Alpha, to break him and tear him apart. Alpha backpedaled out of reach and sent blast after blast from his sword raining on Berserker. They were so powerful that the slightest gesture from either of them sent shock waves through the street. Buildings crumbled and automobiles were tossed like leaves in the wind.
Rin was watching in horrified fascination as the tide slowly turned in Alpha's favor. Even with all his power Berserker simply wasn't strong enough to win. His injuries mounted, and for each new drop of blood that dripped from him Alpha's grin widened just a little bit more. And after he was finished with Berserker it would take only the slightest flick of his wrist to annihilate her and Shirou.
Rin had resigned herself to defeat when she felt a gentle hand at her elbow.
"There's only one thing we can do." Shirou said.
Dear, practical Shirou. Even when defeat was inevitable his only though was how to fight. How to win.
"I'll take Kotomine! You shut that thing down!" He cried and sprinted forward.
Rin followed his lead and ran towards the machine. Shirou dove for Kotomine's throat, his power blazing through his eyes. Kotomine's face broke into a mocking grin that matched Alpha's. He sidestepped with such preternatural quickness that Rin had to check to make sure he wasn't reinforcing himself the way Shirou did. He lazily stepped to the left just far enough to avoid Shirou's attack and twisted as he passed, driving an elbow into Shirou's back.
Shirou's momentum was immediately halted and he slammed downwards into the roof as though he'd had a wrecking ball dropped on his back. The tiles shattered and the wind was knocked out of his body in a whoosh. Kotomine cackled and gave him a kick in the ribs that sent him sliding across the roof.
Shirou gritted his teeth and pushed himself to his feet. His fortification magic flared and he spat out a mouthful of blood.
"I see you haven't learned much." Kotomine said disapprovingly.
He took a short run up, six quick steps and a vicious downward strike. But this time Shirou was ready for him. He danced backwards and caught Kotomine by the wrist. He wrenched him overhead and slammed him down on the roof like he was swinging a sledgehammer. Kotomine bounced away but twisted in midair to land on his feet, supporting himself with one hand on he tiles. His expression had changed to rage.
"I'm not here to quip with you. I'm here to stop you." Shirou said.
"And just how do you plan to do that? Your lover and her pet servant are hopelessly out matched. I have facilities like this one hidden all over the world and an army of your brothers at my disposal. The Grail will be mine in just a few short minutes. But even without the tricks, or allies, or plots, it wouldn't matter. When it comes down to it only one thing matters.
You can't beat me." He said with a grin of malevolent glee.
"I've heard that before. It didn't work out so well for Sigma." Shirou replied.
Kotomine sneered and they closed again in a flurry of blows, blocks, and counters.
Rin ran to the control panel and desperately looked for a way to shut off the magical reaction happening within the swiftly spinning rings. Ilya and Sakura were still spamming and screaming silently as Rin's eyes flicked over a complex set of gauges and dials. She heaved the switch that had started the reaction back into its original position but nothing changed. She hit buttons at random and turned knobs but nothing seemed to help.
She spotted a broken off shard of girder nearby and she scrambled towards it. She raised it above her head and prepared to smash it down on the dark machine when it was blasted out of her hands. She spun and saw Kotomine standing there, his hand drawn back, a long slender sword clutched in his fist. He was preparing to throw but Shirou tackled him from behind.
"Alpha!" He bellowed as they tangled.
"Quit toying with Berserker! Stop the girl!"
A surge of hope shot through Rin. Up until now Kotomine had been haughty. Sure of his victory. But when Rin threatened to smash his machine he panicked. She must be on the right track! If Shirou could keep Kotomine pinned, if Berserker could keep Alpha occupied for just another minute...
She backed up and began to cast, weaving a torrent of destructive ice massive enough to smash the entire contraption.
She was knocked from her feet as a massive explosion rocked the building. Her ears were ringing as she pushed herself up onto her elbows.
Alpha's look of sardonic amusement had disappeared. His sword had blurred into an angry streak of red, the rotating sections spinning like a hurricane. Berserker panted in the center of a crater, forced to one knee by the attack. It was orders of magnitude more powerful than what Alpha had been unleashing.
He's been holding back. Rin realized with horror.
Alpha's mouth pressed into a displeased line and he swung again. This time the blast was so powerful that it scorched the sky and leveled every building in the area still standing. And it wasn't a single simple explosion. It was a continuous wave of power, like a nuclear blast trapped at the moment of detonation raging continuously as Alpha bore down on his sword. Rin's eyes brimmed with tears as she watched Berserker struggle. His power surged, he screamed in defiance and agony. His eyes blazed as he fought like a drowning man to survive. But the attack was in its own class, so powerful that Rin was surprised it didn't crack the very earth.
When Alpha raised his hand again there was nothing left of Berserker at all. He had been disintegrated down to his atoms.
Rin had only one chance. She scrambled to her feet and turned towards the machine. She raised her hands and began to conjure.
But Alpha was too fast. Before she could even mouth the words of a chant he had appeared in front of her. Rin only had the time for a short gasp as her eyes widened.
Alpha reached back and almost casually rammed his sword through her heart.
"NO! NOOOOO!" Shirou screamed, the sound inhuman as it tore itself from his throat.
He released his hold on Kotomine and dashed forward, heedless of the danger. Alpha raised his hand to kill him as he passed but Kotomine forestalled him with a shake of his head and a sadistic grin. He fell on Rin's neck and cradled her body, crying heartbroken tears as he tried to coax some sign of life from her. But it was too late. She was already dead, a fist sized hole punched through her chest, her eyes staring glassily towards the sky.
Rin stood over him as he cradled her body, her head bowed. She reached out to touch him but could not. She looked a her own body and...
She looked at her own body and...
She stood over him as he cradled her body...
Rin's consciousness snapped into a sudden state of awareness. She was standing there un-hurt, watching her own death. She held her hands up in front of her face, half expecting to be able to see through them. She looked around in confusion.
She found herself standing in a great black abyss. Darkness stretched off on all sides of her. Not the close, pressing darkness of a cavern but the open, terrifying blackness of unrestrained infinity. She was looking at her death through a sort of window. No, it was more like a shattered piece of mirror. A crack in reality.
And there was someone with her.
She whirled and her eyes went wide. Caster lay on the ground behind her. His upper body was leaning up against some invisible protrusion. His robes were still soaked with his blood, his body was just as it had been when he had disappeared from the ruins of Ilya's mansion. He was riven with wounds, his blood flowing into the darkness like an endless river and yet frozen in time, suspended at the moment of his death.
Rin's shoulders slumped and she lowered her head in resignation.
"So I'm dead then? Is this hell? Or perhaps something else?" She asked.
Caster shook his head, a serious expression in his partially glazed eyes.
"This was...my final promise. To Ilya. To keep you safe. I...pulled you out of the flow of time before your death." He said with a cough that brought a froth of fresh blood to his lips.
Rin's eyes went as wide as saucers.
"Then this is it? The place outside of time where you exiled yourself!" She said.
Caster nodded.
"I don't understand. When you died...when we thought you died you disappeared. You were coming here, right? To wait for me? Then why do I still see my body lying there?" She asked, turning back towards the window in the world.
"She is you. A version of you. A version that stayed behind. It was the best that I could do, considering." He said, gesturing towards his wounds.
Rin's brow creased in confusion.
"Then I'm not real? I'm...a copy? A shadow?" Rin asked.
"No. No, no, no." Caster shook his head feebly.
"You are as you existed when I pulled you out of the timeline, but a version of you remained. You are you. You think as you do, you feel as you do. You were you right up to the point when I brought you here. And you are still you, but from that point onwards she was you as well. What does it matter what your origins are? She took a different path through the timeline. You are her, and she is you, but you are also yourself. Do you see?" He said.
Rin hesitated.
"I don't know. I..." She began, but her breath caught as she turned back to the rift.
The scene was still unfolding in front of her.
Shirou was still slumped over her corpse, tears streaking the grime of combat that smeared his face. Alpha stood at Kotomine's right hand. Kotomine was talking, taunting him.
"...e's dead. Because of you, Omega. Everything you touch dies. If she had never met you, if you had left her well enough alone, if you had joined me when you had the chance, she would still be alive. Everyone you meet dies. Because you're toxic. You're a disease, an inhuman piece of..."
"Shut up! I'm done with your lies! GO TO HELL!" He bellowed.
He jerked himself backwards before Kotomine or Alpha could react. With his left hand he reached out and jammed his hand into the spinning rings. They crashed to a halt on his hand, neatly severing half his fingers but jamming to a stop on the rest of his arm. He ignored the pain and shot his other hand out, plunging it into the seething mass of raw energy coalescing there.
Time seemed to slow. Or perhaps it did slow under Caster's influence. Power surged through Shirou and his form began to change. The makeup of his body seemed to quiver and jump.
"What's happening?" Rin asked tersely.
"Look closely. Remember what you know about him." Caster replied.
Rin squinted and focused her third eye. She was nearly blinded by the amount of raw power raging over the city. When she realized what was happening she gasped.
"He's summoning a servant!" She said.
Caster nodded.
"But that isn't all. Look closer." He wheezed.
"He's...it's his brand of Magecraft. He can't affect anything except for his own body. That means he can't link to the plane where heroic spirits reside...nor can he summon a servant anywhere except..."
Rin's eyes went wide.
"There's only one place that he could summon a servant from: his own body. And there's only one place that he could summon a servant to: his own body. So he's summoning himself, into himself, as a servant. This is it! This is when he becomes Berserker!" She said in horrified awe.
Since he was summoning from the same place and to the same place the magic began to loop back on itself, cycling and cycling in an infinitely recursive loop fueled by the dual Grail. Everything made sense. Berserker's claims of actually being Shirou, even his glitched mad enhancement repeating infinitely.
Even as he transformed he was chanting.
"What is he saying?" Caster asked, craning his neck feebly.
"I've heard that before. It's something Sigma, Shirou's clone said. It increased his power but it sent him into a mindless killing rage." Rin replied with horror.
"Burst limit override initiated.
Steel take my body. Fire burn my blood.
I have dealt many thousand blows.
I have received many thousand in return.
Heedless of loss, heedless of gain.
Ignoring pain, and despair, and defeat.
Without regret, let rage fuel my power.
This I pray.
Unlimited Rage Works!"
There was a sudden lull like the eye of a hurricane passing directly overhead. And then Shirou's world tore itself apart. Tears rolled down Rin's face as that berserk look, that wave of unbridled hatred and fury descended on his gentle features like a demonic mask. Any semblance of humanity fell away like a cloak. His jaws cracked open and the most unearthly, terrifying sound she had ever heard issued out like the scream of an imploding star.
He dashed forward and his movements were so fast that the air behind him ignited from the friction of his movements. Alpha didn't stand a chance of intercepting him. His first punch nearly liquefied Kotomine. There wasn't enough of him left to hit the ground.
But Shirou's rage was unbridled. He was unable to stop, unable to control himself any longer. Alpha tried to fend off his attacks with a desperation fueled by panic. He launched salvo after salvo of blasts from his spinning sword. His onslaught scorched the heavens and cracked the bedrock of the city. Thousands of screaming citizens died as the two titans battled back and forth. A volcano marked their battle as one of Shirou's strikes cracked the bedrock. Steam billowed out like the mouth of hell as water rushed in. When an innocent got in his way Shirou simply walked through them fast enough to aerosolize their bodies.
A thin rain of blood began to fall over the city.
When Alpha at last succumbed to panic he fled, using every noble phantasm in his arsenal to escape, to slow down his pursuer, to extend his life for just another instant. Shirou followed him so fast that he ignited the air with friction. He had burned away most of the atmosphere by the time they collided again. They beat the mountains into valleys. They redistributed the oceans over the face of the planet as they waded through them. They battered each other with geographical features. When Shirou slammed the moon into Alpha he obliterated a quarter of the planet.
And at last, when Shirou stood in the scattered remains of Alpha's corpse, his rage still burned. He rampaged across the surface of the planet destroying everything in his wake until not even microbial life remained. Every city that he crossed was razed in an instant. Every person on the earth perished in the fires of his vengeance.
And through it all Rin watched, and wept, trapped outside of time with a dying spirit. When she could bear it no longer she turned her face away. And when she could no longer bear being apart from Shirou, even the monster he had become, she turned back.
...
Time lost meaning but there was a moment separated from other moments. After Shirou had destroyed the world her eyes sharpened and she turned back to Caster.
"We have to do something." She said for the thousandth time.
"There's nothing we can do." He replied sadly for the thousandth time.
"No. That can't be true, I won't accept that! You could bring him here. With us. You could pull him out of the timeline and stop this destruction."
"To what purpose? Whatever can be destroyed has been destroyed. Nothing remains to be saved."
Rin paced and scrubbed tears from her cheeks.
"What about before? We're outside of time, right? So we can return to any point in the time line. Take us back to before he became...this. We can stop this from ever happening in the first place!"
Caster shook his head.
"I am too weak. I could take us back but I cannot navigate the flows of time. We might arrive a hundred years before he was born, or a hundred years too late."
"What if you had a beacon? A marker in the time line to aim for?"
Caster considered for a moment.
"That...might be possible." He said hesitantly.
"There was a massive burst of grail energy when he transformed, right? Can you find that and take us back to that moment?"
Caster's eyes lit.
"I can! But Rin, if I cast him out of time this reality will collapse. I cannot maintain it. You, me, we will both perish."
Rin didn't hesitate.
"That doesn't matter. We have to stop this, whatever the cost." She said with determination.
Caster still wavered.
"But even this is not guaranteed. In my weakened state all I can do is target massive sources of grail energy and pull them out of time. I might not arrive at the correct moment. I might pull a different Servant and things would happen in exactly the same way. There's too much that could go wrong." He said.
Rin knelt by him and took his hands in hers.
"It's worth trying. Anything is better than...this." She said, gesturing at the rift.
Caster looked into her eyes for a long moment. At last he nodded.
"Besides. I think...I think I know what happens next." Rin said.
Caster quirked an eyebrow at her but she shook her head.
"Please, just try." She said, a pleading note in her voice.
Caster nodded and leaned back. He closed his eyes.
For a long moment nothing happened. And then imperceptibly the lines of reality began to quaver. There were no walls in the vast emptiness that contained them but if there had been they would be shaking. Caster's brow furrowed in concentration and his knuckles went white as he clenched his fist around Rin's hand. Blood began to flow from his wounds once more and once more Rin could detect the life ebbing from him. The edges of the rift back into reality began to splinter and fold back in on themselves. Rin looked back.
She could see time turning back like a video cassette being rewound. Slowly at first, and then faster and faster. She could see Berserker rampaging back across the landscape, gouts of flame and blasted tracts of land healing themselves as his presence was erased. She watched his titanic battle with Alpha once more, this time in reverse. It would have been comical were not the circumstances so dire.
There was a sound like shattering glass and a rift shot out across the sky of the dark pocket dimension, a skittering finger of white on black like a lightning bolt that did not fade. A chaotic wind sprung up and Rin could feel the ground quaking beneath her.
"What's happening!?" She shouted over the din.
"Reality is...fracturing." Caster said between gritted teeth.
"The space we're in is collapsing?"
"No...not just here...the spell, it's feeding off the grail explosion. If this keeps going...everything will..."
Rin's resolve wavered. On his own Caster could probably cast Shirou adrift in time. But with the full power of the twin grails being siphoned into his time controlling magic there was a very real possibility that he would shatter reality itself. There was just so much grail energy infusing everything in the time line that everything was being boosted to impossible levels.
Rin looked back through the rift as another crack splintered the pocket dimension. They were back on the roof. Time slowed again as she watched events play themselves out in reverse. Shirou screamed. Alpha drawing his weapon out of her body as he stabbed her in reverse. Berserker annihilated. And there, just as he was about to strike, time ground to a halt.
Behind her Rin could feel Caster gathering his energy for one final push, one last heave to cast Berserker out of the time line. In front of her Rin could feel the membrane between herself and reality stretch like a bubble about to burst. The thinnest touch would shatter it.
And yet...
Rin's mind opened up with sudden realization. She knew exactly what would happen, exactly what she had to do.
"No!" Caster cried as he sensed as sudden burst of energy from Rin.
But there was nothing he could do.
She reached out into the fabric of reality. As soon as the bubble was breached there was the sound of a thousand mirrors shattering into dust. Reality tore itself apart. But in that split second before the pocket dimension destroyed itself, Caster, and Rin she had time for one single spell.
She reached out with the thinnest, barest thread of prana, a thread that bolstered and reinforced the grail energy flowing like a waterfall. She linked Alpha, Berserker and the Grail itself, reinforcing the bond that they all shared. It was the only way to guarantee that Caster's spell would hit the correct target. Caster would throw Berserker out of time, and that would pull Alpha and the Grail itself with it. It was the only way. Rin knew that nobody could control that much power responsibly. And so she would use Caster's spell to seal it away in a realm outside of time.
But she never found out if her final trick would work. She didn't know what would happen to the Grail, or Alpha, or her other self, or Berserker. But she knew what would happen to Shirou. She knew because she had already seen it. She had been living it. He would be cast out of time, yes. But the exile would not last for more than an instant. He would be pulled out of the timeline and drift backwards until he was drawn back to the single largest burst of Grail energy before his dark transformation.
The night that Rin summoned Berserker. It seemed lifetimes ago, but Rin would summon the being that was now Shirou to herself. He would become Berserker, her protector, her champion. And events would continue like a wheel.
...
Reality cracked and split apart. It fell away like leaves. Rin felt her consciousness standing on a great pinnacle, the highest mountain peak possible. All around her she saw time flowing away like rivers, collecting in pools of delicious possibility. As if through a series of mirrors Rin looked through those pools. She saw all the people of the world, living and dying, loving, killing, struggling, and triumphing. She saw a sea of infinite possibilities stretching in front of her, what might have been.
She saw Shirou as a young boy, leaping again and again to vault a high bar under a sinking afternoon sun.
She saw him standing beside a victorious Kotomine, a dark enforcer that spread his word to every corner of the earth.
She saw him perish in a fire as a child.
She saw him grow and marry and raise a family, normal and happy and completely unaware of his potential.
She saw him in a passionate embrace with a young woman with golden hair and gleaming armor.
She saw herself standing by his side. She saw every imaginable configuration, saw a dozen different iterations of their life together. She saw them as friends, as enemies, as rivals, as lovers. She saw fights and adventures, boredom and excitement. She saw children and grandchildren and, at last, happiness.
She touched her cheek and felt tears there. As reality decayed she smiled, and closed her eyes, and let infinity swallow her.