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English
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Published:
2026-08-03
Completed:
2026-09-23
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13,412
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9/9
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Fate/Alter Ego

Summary:

When Shirou and friends take a much-needed vacation to Metropolis, they discover that not all is well in the shining city. A new Holy Grail War has erupted, and the Fuyuki trio are caught right in the middle! With a mysterious stranger manipulating the war from the shadows, they'll have to use all of their wits, experience, and moxy just to survive. Where's the Justice League when you need them?

Chapter 1: World of Cardboard

Chapter Text

Shirou Emiya watched the world go by underneath him through the airplane window. The rays of sunlight danced across the curved sill as the ocean moved. The sunlight glinted off Illyasviel’s platinum blonde hair. She had the window seat. He heard a shift to his left, and he glanced toward the aisle seat. Rin Tohsaka sat there, sipping a paper cup full of shitty coffee and grumbling. Her teeth looked like they might crack under the tension of her jaw.

“Are we there yet?” She half-whispered. 

“Almost,” Shirou said. He placed his hand on hers, feeling the warmth of the cup through her fingers. “Once we land at LAX, we'll officially be on American soil. You can grab a nap.”

“What I need is a stiff drink!” Rin downed the last of her coffee. Shirou had to suppress a smile.

“After everything we've been through, it's hard to believe that you're afraid of flying,” Illya mused, only half-distracted by the in-flight movie.

Rin tossed her hair, turning her head to hide her pout.

 

“So, Shirou,” Illya asked, kicking her feet. “What's the first thing you want to see when we land in Metropolis?”

“That's easy,” Shirou replied with a grin. “The Daily Planet! I want to see the sun gleaming on the globe… I can't think of anything more inspiring!”

“Not even Centennial Park?” Illya teased. “With that huge brass statue of the boy scout?”

Rin scoffed.

“What's the matter? Don't you like Superman?” Illya pressed, her deep red eyes locked on Rin.

“Why would I care about a guy dressed in red underpants, screaming about truth and justice? I've got Shirou for that,” Rin snapped back.

“You didn't have to come,” Illya huffed. She turned to look out the window, suddenly disinterested in the movie.

“But I'm glad you did,” Shirou added, trying to make peace between the women in his life.

“Whatever, you big sap.” Rin rolled her eyes and turned away. Still, she couldn't help the faint smile on her lips.

 A week in a fancy hotel in Metropolis definitely beat spending that time alone.

“Hussy.”

Rin’s eyes narrowed. She just had to survive Illya for the week… and get some alone time with her man.

 

The plane finally landed in Los Angeles, and Rin made a beeline for the airport bar. She slapped her passport on the bar with a haughty smirk.

“Bartender, pour me a glass of Sapporo,” she ordered. The bartender adjusted his glasses as he looked at the woman's ID.

“Sorry miss, I can't sell you beer. You're too young.”

Rin cracked like a mirror.

“Too young? I'm nineteen! Check it again!” She demanded, as if the number would somehow change.

“Rin, the drinking age in the US is 21,” Shirou reminded her. 

Rin put her head in her hands, sobbing weakly in defeat. Illya hopped onto a bar stool and produced her passport.

“Can I get a glass of Sapporo, sir?” She asked, batting her eyelashes sweetly.

“You've got a very youthful face,” the bartender said as he poured the drink. 

Illya took the drink and savored a long sip, the foam lingering on her upper lip like a mustache. Rin glared at Illya. Then, she shifted closer.

“Illya, sweetie… I know we don't always get along…” Rin trailed her fingers slowly along the polished bar. Her voice dripped with sweetness - not like sugar or honey, but like aspartame.

“But if you buy me a beer, I think we can put all that nastiness behind us and be friends. Better than friends! How about… best friends?”

Illya stared right through Rin’s blatant manipulation.

“Sorry, but this stuff is for adults,” she replied with a smug smile. “Not little girls.”

 

Rin grit her teeth and reached for the gems in her pocket. Shirou grabbed her from behind, pulling her back.

“Rin, no!”

“Rin, yes!” Rin shrieked, flailing against Shirou’s grip. Illya laughed as she paid for her beer, tipping generously for the bonus entertainment.

 

Finally, the plane landed in Metropolis. Shirou led the way through the bustling airport. After a quick cab ride into the downtown core, the Fuyuki trio stepped out into the city. Bags in hand and eyes wide with awe, they looked around. The buildings towered over them, like giant fingers reaching up to touch the sun.

“There it is!” Rin called out, swept up in the awe. She pointed to the massive spire of the Daily Planet, dwarfing the other skyscrapers around it.

“It seems like a lot for just one newspaper,” Illya mused. Shirou produced his travel guide.

“According to this, the first few floors are leased out to other companies,” he read aloud. “It helps the company stay profitable, even as physical newspapers are phased out in favor of digital media.”

“What an American solution,” Rin nodded thoughtfully. “So, where to next, Mr. Tour Guide? But I'm warning you - there is a right answer.”

 

Shirou racked his brain for a moment. What would Rin want to see in Metropolis?

“How about STAR Labs?” He offered, his eyes meeting Rin’s.

“Good boy.” Rin pat him on the shoulder.

 

The three stepped off the bus and into the pristine white halls of STAR Labs. Even Rin couldn't hide their excitement as she raced around the lobby.

“She's really bouncing off the walls.” Illya crossed her arms.

“Let her be, she'll burn off that airport coffee.” The memory of the bitter taste made Shirou's hair stand on end. “She'll sleep like a baby tonight.”

 

The trio joined a tour group, following the guide around the building. Illya began to doze off, but Rin paid rapt attention. She raised her hand and pointed to a sample of glowing green stone beyond a guarded partition.

“Is that kryptonite?” She asked the tour guide. The guide nodded enthusiastically.

“It is! That sample of kryptonite was created right here at this facility. When Metallo shot Superman in the heart with a kryptonite bullet of unknown origin, Cyborg was able to use our sample to focus his beam into a surgical laser. With that, the Justice League extracted the bullet. Naturally, we keep the sample for study… and as a point of pride.”

“So the same weapon that was created to kill Superman… was used to save his life…” Shirou breathed in awe. “That's so poetic…”

 

As the Fuyuki trio toured STAR Labs, a sinister fighter watched a monitor from the shadows. Though his face was concealed in the gloom, a pit of sickly green liquid cast a noxious light on his emerald green cloak.

“Daughter,” he commanded. A woman in black knelt at his word. Her green eyes shone with cruel intelligence, and a crimson sigil seemed to be burned into the back of her right hand.

“Yes, father?”

“The lesser Grail has found its way to Metropolis,” the shrouded figure said, tenting his fingers.

“This is not as we planned.” The woman grit her teeth.

“No.” The man smiled, though it didn't reach his eyes. “But it makes things easier for us.”

“What do we do?”

“We accelerate our plans.” The man rose to his feet. “Gather the League of Assassins! We now move into phase 2 of Operation Alter Ego!”

 

The sun was setting over Metropolis, the orange sky quickly melting into violet. The last rays of sunlight glinted off the Daily Planet globe as the Fuyuki trio trudged through the city streets. Illya licked a delicious strawberry ice cream cone.

“Don't tell me we're lost,” Rin complained as Shirou fumbled with the map.

“We're not lost,” he reassured her. “These streets are just so confusing!”

“If we're not lost, then why are we not at the hotel yet?” Rin turned to face Shirou. “I just had a 16 hour flight, not to mention three hours of sightseeing! Right now, the only thing I want to do is go to our hotel and fall face first into bed!”

 

The Daily Planet door opened, and a woman stepped out. Her heels clicked against the sidewalk as she breezed by the trio. Illya stopped dead in her tracks, overwhelmed by a familiar presence.

“Ber… serker…?” Her voice was soft. Quavering. The ice cream fell from her grasp, landing with an undignified splat on the sidewalk.

“Illya? What's wrong?” Shirou asked, leaning down to tend to his adoptive sister. 

Rin glanced at the woman walking ahead of them. From her dark bob haircut, her eyes trailed down to her right hand. They went wide as she registered the crimson seal burned into the stranger's skin.

“Shirou,” she said, tugging softly on his sleeve. “That woman… she has command seals…”

 

The words made Shirou's heart stop. He turned to face the woman. She'd stopped walking, now standing stock-still on a street that was far too empty for comfort. She turned her head back to look at the three, and Shirou could see the deep, dark bags under her eyes.

“You know what these are?” She asked. She turned to step closer. “That means you can help him.”

“Help him?” Shirou asked,  his entire body trembling. He could feel the magic in the air - it was like there was a static charge all around him.

“Who are you talking about?” Rin demanded, standing her ground. She reached into her pocket for her gems.

“You have to help him… please, I don't… I can't!” Desperate tears fell from the woman's cheeks. She fell to her knees, still crawling toward the tourists. She reached out, her hand trembling. “I can't save him!”

 

A figure manifested behind the woman, looming over her. His entire body was wreathed in dark blue, save for his head. A scarlet cape unfurled from his shoulders as he stepped forward. His eyes burned with fury, but Shirou could only see the letter stamped proudly on the figure’s chest.

 

It was a huge S.

 

“Run!” He shouted. Rin didn't argue. She grabbed Illya by the hand and took off down the street. They dashed as quickly as they could, hearts racing and breath coming in heavy gasps.

 

They weren't fast enough. Berserker moved like a lightning strike. Shirou had barely blinked, and the looming figure already stood over him. He raised his hand over Shirou, curling it into a fist. Then, he struck.

“Rho Aias!” Shirou barely had enough time to manifest his shield. The barrier cracked under the awesome power of Berserker, before breaking with enough force to send Shirou flying backward. He overtook Rin and Illya, rolling to a stop on the street just in front of them.

“Shirou!” Rin screamed. She knelt over him, trying to help him to his feet. Shirou groaned in pain.

Berserker stepped closer. His eyes glowed with a hateful red, a deep and untethered rage. It was as if a monster had been unleashed in a world of cardboard.

“Shirou, come on,” Rin pleaded. “You gotta get up!”

Shirou could barely see through the blood pouring over his eye. The world was red to him, but he could still make out two pinpricks of light that shone through it all. Berserker planted his feet.

“Clark, stop!” His master begged.

I've been through so much, Shirou thought. If I can't save Rin… or Illya… I'll never forgive myself.

Shirou closed his eyes.

Holy Grail, I've reached out to you before. I know you, and you know me. So… in my time of greatest need, I beg of you!

Time seemed to slow as Berserker leaned in. The glow in his eyes began to flash outward, firing in a beam.

Shirou's eyes snapped open. He felt a burning sensation, but not the feeling of a man being roasted by heat vision. No, this was a familiar burn. A burn on the back of his right hand.

“I need a hero!”

Rin and Illya covered their eyes, unable to face their sure destruction. Berserker's heat rays flew out from his eyes, but didn't strike the tender flesh of tourists. Instead, they bounced off a gleaming bronze shield. Berserker stepped back, seemingly shocked by the arrival of the stranger. Between him and his prey stood a woman with raven hair. She wore form-fitting armor, ancient and gleaming, and a tiara that shone in the night like the sun. In her left hand, she held that perfect bronze shield. In her right, a flawless sword. She swung the sword in a graceful arc, demonstrating her peerless skill in the motion.

“By your call, I am summoned,” the woman said. “I am Saber, and you are my master.”

Her eyes fell on Shirou's command seals, and she smirked.

“You've done this before.”

“Seriously?” Rin shouted. “Why does Shirou always get the hot ones!?”

 

Berserker flew forward at breakneck speed. Saber raised her shield, blocking his charge. The concrete cracked under their feet as the two struggled for dominance. Berserker threw a second punch, sending Saber spinning. She hit the ground hard, her shield clanging off the concrete.

“Go, go, go!” Shirou urged. 

Rin and Illya clambered to their feet and dashed down an alley. Shirou followed, glancing back at Saber. She locked eyes with him. She nodded, a silent plea for him to escape. Berserker bore down on her, smashing a devastating punch into her shield that shattered the street beneath her.

“Saber!” Shirou called out, his heart racing. Saber planted her feet and rose, battered, but still standing. She swung her blade, parrying Berserker's fist before rushing to Shirou's side. She scooped him up under her arm, running through the alley with incredible speed. At that pace, it wasn't long before they caught up with Rin and Illya.

“I cannot protect you if you don't run away!” She chided him.

“I can't just let him kill you!” Shirou protested, despite the undignified position he was being carried in.

 

 WHAM!!!

 

Berserker landed in front of the group, cracking the concrete beneath his feet. He lunged at Saber once more, knocking her off her feet with a solid punch to the jaw. She dropped Shirou as she spiralled, crashing to the ground. Berserker stepped over Shirou, approaching Saber as his eyes glowed with heat and fury once more.

“Saber!” Shirou ordered. “Use your Noble Phantasm and stop Berserker!”

Saber stood, taking a deep breath.

“The Golden Lasso of Hestia compels you!” She declared.

Shirou watched in awe as Saber drew the golden rope from her belt. She twirled it over her head, then encircled the rampaging Berserker in the rope. She pulled it taut with a flick of her wrist. Berserker struggled against the rope, roaring with fury as he tried to break free.

“Submit to me!” Saber ordered, her eyes glowing with power.

“Nice!” Illya cheered, jumping with joy.

“Now's our chance!” Rin led Shirou to the street. They had to get out of here.

 

The ground began to rumble as a powerful engine approached them. Rin jumped back just as a sleek, black ride screeched to a stop in front of her. An afterburner mounted on the back of the car still thrummed with heat - Shirou could feel it washing against him in waves.

 

The canopy of the car opened, revealing a pair of masked men. At the driver's seat, a muscular man with a cowl pulled over his eyes. Two points poked out of the top, like the ears of a creature of the night. By his side sat a younger man with dark hair, wearing a domino mask. A blue bird adorned his form-fitting bodysuit - maybe a hawk?

“Get in,” the man in the cowl ordered sternly.