/* "This story draws inspiration from the 'system' in Solo Leveling while taking place in the Fate/Extella Link universe. The narrative follows the structure of Fate/Grand Order's Singularities as its setting." */
Happy Reading!
A low hum rippled through the air like distant thunder—subtle at first, but Charlemagne's instincts caught it instantly.
From his perch atop the crumbling overpass—what remained of a once-busy expressway near the outskirts of Fuyuki—he gazed down at the ruined cityscape below. The world had changed since Karl der Große came.
Where there was once greenery and the quiet calm of Fuyuki Park, now there sprawled a militarized complex—cold steel over scorched earth. Watchtowers pierced the sky where cherry blossoms once bloomed. Concrete walls and automated turrets formed a jagged perimeter. Metal-plated roads cut through the landscape like surgical scars, and walking beneath them were squads of uniformed assimilated soldiers and armored AI. The heart of the base beat with industrial precision.
The park was gone. Just another piece of Fuyuki consumed by Karl's vision of order.
Then the air shifted.
The sky darkened—not like dusk, but as if a divine curtain had fallen. Clouds parted with eerie precision. There was no wind, no sound, only pressure—like the atmosphere was holding its breath.
Charlemagne's eyes narrowed.
From the rift above descended a titan.
No, not a titan. A fortress.
Engines of golden light pulsed beneath its structure, keeping it aloft without effort. Magical crests rotated beneath its surface in concentric circles, each one humming with restrained power. Its hull was a fusion of cathedral and warship—black and gold plating interwoven with arcane script, gothic spires extending skyward like the teeth of a divine predator.
Carolus Patricius.
Charlemagne's breath caught.
He knew that name too well. It was more than Karl's floating fortress—it was a symbol. A shrine to his ideology, a dreadnought forged not just to wage war, but to rewrite the world beneath its shadow.
No fanfare. No trumpets. And yet, everything stopped.
The base below ground froze. Patrols halted mid-step. Lights shifted hue. Turrets locked position not outward—but inward.
Then, as if summoned by judgment itself, three lights descended from the heart of the fortress.
Figures coalesced in the golden haze. The first, unmistakable, landed at the center.
Karl der Große.
Clad in resplendent white and gold armor, his figure hovered inches from the ground—never touching it, never needing to. His cape rippled with unnatural rhythm, and his silver hair was bound in flawless precision. A crystalline half-mask obscured the top of his face, letting only his luminous eyes shine through, calm and cold as law incarnate.
He did not walk.
He glided.
Not a man. A monarch. A concept in motion.
Charlemagne's grip tightened near his sword, but he didn't draw.
He didn't fear Karl.
He respected him—like one respected a star collapsing into itself.
Karl didn't conquer by force alone. He transformed. What he touched didn't fall. It was… corrected. Rewritten into something unrecognizable—and in his eyes, something better.
To his right, the second figure touched down with mechanical grace.
Archimedes.
Charlemagne had never met him, but the descriptions from Vanguard intelligence were unmistakable: white robes trimmed with gold and deep violet, a high, rigid collar rising like a blade, and tousled brown hair that shimmered faintly beneath the hovering lights. A golden monocle gleamed on one eye, and his expression was razor-thin—emotionless, calculating.
No armor. No weapon.
But no one here would mistake him for harmless.
He didn't fight battles. He designed them.
And to Karl, that made him far more valuable than any sword.
Charlemagne's breath hitched as the final figure descended.
No ceremony. No signal.
Just a slow drift from above like a shadow peeling from the clouds.
A woman—at least in shape—wrapped in armor the color of twilight. Black-violet metal, jagged and asymmetrical like it had grown around her rather than been forged. Her long hair floated unnaturally, moving with the same rhythm as the fortress behind her. Her crimson eyes scanned the ground like a predator. A long, barbed spear rested in her hand, trailing with quiet intent.
No one moved.
Charlemagne's stomach turned.
He didn't know her. He had no name to attach, no file in the Vanguard's archives.
But he didn't need one.
She was the kind of Servant that didn't need introductions.
Her presence alone made the air heavier. A living omen.
"She doesn't command fear…" Charlemagne whispered. "She is fear."
The three stood in perfect formation. Karl at the center, Archimedes to his right, and the nameless nightmare to his left.
The message couldn't be clearer.
This wasn't routine. This wasn't surveillance.
This was intent.
Charlemagne's thoughts raced.
Three Servants. One of them Karl himself.
This wasn't just another outpost. It was his stronghold—one of many seeded across Seraph. But unlike the others, this one held more than data, armaments, or territory.
It held prisoners.
Important ones.
And now Karl had come to collect.
Charlemagne's gaze flicked back toward the base's interior. No movement. No flare. No sign from Ren.
Still inside.
Still silent.
Maybe they knew about the infiltration.
Maybe they knew he was there.
Or worse—maybe they knew why he was there.
His thoughts snapped to Jeanne.
Her name struck like a hammer. Not a comrade. Not just another Servant.
A beacon. A flame in the dark. A soul that refused to break, no matter what Karl's soldiers or assimilation programs threw at her.
And now… the emperor himself had come to her door.
He could feel it—this wasn't a retrieval.
This was a message.
A statement. That even the brightest lights could be bent to serve.
Or extinguished.
But… what if Jeanne wasn't the reason?
Charlemagne's mind drifted to Ren.
There was something different about the boy. Something not even he could put into words. A defiance in his step, a kind of quiet resistance that didn't fit the mold of most Servants—or even humans.
Could Karl know?
Could he be here… because of him?
Charlemagne exhaled slowly, retreating a single step from the ledge. The wind stirred the ruined concrete beneath him.
He couldn't face this.
Not alone.
But he didn't need to—not yet.
He just had to survive. To watch. To find the single moment, the single crack, when he could strike—or run.
Because this wasn't overkill.
It wasn't spectacle.
It was a culling.
A future descending like a guillotine.
And he would be damned if he let it fall without a fight.
The electronic door hissed shut behind Ren, sealing him inside the dim corridor. The air was stale—processed, dry, and tinged with the faint chemical bite of antiseptics and metal. He pressed his back to the wall, heart hammering in his chest. No sword. No gun. No Persona. Only instincts… and two skills that had saved his life more than once.
He closed his eyes and activated Third Eye.
The world shifted. Colors bled out. Lines sharpened. Sounds became layered, ordered—like threads he could pluck or sever. Every flicker of a security camera, every out-of-place vibration in the wall, every footstep echoing beyond reinforced doors—he saw it all, felt it as clearly as breath on his skin. In the monochrome overlay, a faint golden trail shimmered—subtle, almost unwilling to be seen.
A path.
He followed it.
Step by step, Ren moved like a shadow stitched to the walls, barely stirring the air. His breath was shallow, measured. Every turn brought him closer—he could feel it. Faint voices, muffled and weak, filtered through the reinforced bulkheads. No alarms yet. No metal boots clanging toward him. The clock was still ticking in his favor.
But not for long.
He found the chamber—a door marked with multiple layers of magical seals and mechanical locks. Not meant to keep enemies out. Meant to keep prisoners in.
His fingers ghosted over the lock panel. Third Eye flared again.
Wards. Embedded circuits. A tripwire on a trigger line. Whoever designed this didn't expect infiltration—but they sure expected escape attempts. With practiced hands, he traced the anomaly, found the bypass. A single misstep and the entire wing would light up red.
He exhaled. Focused.
Click.
The door eased open.
And Ren slipped inside.
The room was larger than he'd expected—an old observation hall, walls lined with ruined terminals and scorched markings, converted into a holding pen. Dozens of eyes turned to him as the door closed behind him with a soft hiss. Half a dozen figures were sprawled across the floor—some upright, some collapsed in exhaustion. They looked up at him with shock, fear, disbelief. Not one of them recognized him.
Because they couldn't.
These were the captured Vanguard—the ones who had been taken before Ren even arrived at base. Their armor was damaged, some still wore the cracked emblems of the resistance, others were in civilian clothing—scavenged, torn, scorched. Human, AI, young, old—it was a desperate spectrum of survivors. None dared speak.
A woman stood up slowly. Her steps were weak but dignified, posture held with iron despite the bruises and grime. She stared at Ren as though trying to determine if he was real—or another cruel illusion sent by their captors.
"You're not one of them…" she said, voice raspy. "But you're not one of us either. Who are you?"
Ren opened his mouth, but hesitation gripped his throat. What could he say? There wasn't time to explain. No name would mean anything to them. So instead, he offered what little reassurance he could.
"I'm here to get you out."
Murmurs rippled through the group. Uncertainty. Hope—and fear. The kind that burned worse than despair.
"You're… from the Vanguard?" one of the younger AI units asked, eyes glowing faintly behind cracked lenses.
"That's right." Ren admitted. "I joined after you were taken. You don't know me. But I'm not your enemy. And we don't have time."
Another man, a civilian medic by the look of his stained coat, stood shakily. "If this is some trick—if you're here to finish what they started—"
"I'm not," Ren said firmly, stepping back to the door and scanning the corridor with Third Eye. The path was still clear, but it wouldn't be for long. Every second they lingered, the risk of being caught increased. His pulse quickened as his mind raced through the possibilities—every delay, every hesitation felt like a countdown.
"If we don't move now, it'll be too late," Ren added, his voice tight with urgency. He glanced at the prisoners, his gaze sharpening. "They haven't found us yet, but they're going to start searching soon. We don't know when, but it won't be long. And once they do, there's no escaping."
He took a step forward, his eyes scanning the hallway again, heart hammering in his chest. "We need to leave, now. Or we're not going to get out at all."
"Is this everyone?" He asks.
Silence. Then the woman—the same one who first spoke—lowered her head and exhaled hard. "They already took the others an hour ago. A full batch. We heard the screams."
Ren nodded grimly. "Rin sent me. Said there might be survivors. She mentioned your name from a report. 'Saint Martha.'"
The woman's eyes widened—just a fraction. "You spoke with Rin…?"
"She didn't forget you."
That, more than anything, was what broke the tension.
"Alright," Martha said, voice still wary but more focused now. "If you're lying, you'll answer to me. But if you're telling the truth… then lead."
"I'll cover us," the AI added, pulling a fractured panel from the wall and jury-rigging it into a makeshift shield. "Sensors are tight in this quadrant. If we can disrupt the signal nodes—"
"We don't have the gear to mount a real jamming operation," another added—a young woman with burn scars along her jaw. "We need stealth. If they so much as glimpse us, the whole place comes down on our heads."
Ren nodded. "That's where I come in. I can… sense the safe path. I'll guide us. Just follow my lead. No questions, no delays."
They moved.
Step by step, quiet as ghosts.
Ren took point, eyes wide, scanning the digital threads of Third Eye. Doors, vents, guards—the world was a minefield and he was the only one with a map. Once, they had to stop—an automated drone hovered just around the bend, its searchlight sweeping toward them. Ren signaled with a hand, Phantom Step flaring for just a moment as he blurred across the hall, planted a boot against the wall, and twisted a loose panel. The drone's optics glitched—just long enough.
Move.
They advanced.
Behind him, the medic helped a limping AI walk. Martha held the rear, eyes sharp, grip tight on a cracked length of pipe. There were no weapons. No miracles. Just trust.
And then—
A noise. Too close. Boots. Voices.
"Squad Six, check the eastern hall—sector breach detected—"
Ren's pulse spiked. They'd tripped something. Time was up.
Third Eye flickered wildly. No escape route—no clean one.
His eyes locked onto a maintenance duct, half-hidden behind fallen debris. Narrow. Cramped. One by one. Risky.
"Here! Go!" he hissed.
Martha didn't hesitate. She grabbed the smallest among them, shoved him into the vent. The others followed, scrambling, crawling through the dust and rust as the voices drew closer.
Ren waited—last as always.
Footsteps pounded down the corridor.
He clenched his jaw.
Then—Phantom Step.
In a flash, he surged forward, slamming the vent shut just as the patrol rounded the corner. His body blurred—vanished behind a pillar. The guards looked around, weapons raised.
Nothing.
One guard's voice crackled, flat and mechanical. "Sensor fluctuation detected. Recalibrating parameters."
The other responded with an emotionless grunt. "Irregularity within acceptable range. Proceed with patrol." They passed.
Ren slid into the vent, lungs burning, mind racing.
Still alive.
Still unseen.
For now.
And the mission wasn't over yet.
The vent led to the tunnels twisted beneath the facility like the veins of something long buried and still alive. Every footstep echoed too loudly in Ren's ears, like a warning waiting to become reality. The group pressed forward in staggered formation—no formation at all, really, just a collection of wounded, terrified people struggling to move as quietly and quickly as possible.
But it was too quiet.
Too still.
Each turn felt like it could be the one that ended in a patrol, or worse.
Ren flicked on his Third Eye again, scanning ahead—light traces of magical detection fields shimmered just around a corner. He paused, hand raised in warning, his voice low but clear. "Wait."
The group froze behind him, breath held, the air tight with tension.
"There's a trigger up ahead. Magical field. We move through it, they'll know we're here."
Saint Martha stepped up beside him, her expression taut with focus, though exhaustion pressed beneath her eyes. "Can you bypass it?"
Ren studied the structure—a faint distortion in the air, anchored into the wall by glowing runes. "There's a blind spot in the far corner." He pointed. "I can take a few people through one by one. It'll take time, but it's safer."
A groan sounded from the back—one of the wounded had stumbled. A young AI unit, limping heavily, caught the injured man's arm to steady him. "Careful. We can't make noise like that."
"I'm trying," the man gasped. His face was pale, bandages around his abdomen already soaked through. "I'm not sure I can walk much further…"
"You have to," another soldier urged him—this one human, mid-thirties, gaunt but steady-eyed. "We get out, we get you help. But if we stop now, none of us makes it. You got this."
"I can carry him," said a third—an AI with a fractured arm, sparking slightly at the elbow. "As far as I can go."
"You shouldn't even be moving," the soldier protested.
"We don't have time to argue," Saint Martha cut in, her voice firm but not unkind. "Everyone counts. We move together."
Ren nodded and moved toward the edge of the field. "Alright, first three with me. Quiet. Fast."
They followed him, huddling close as he guided them through the distorted corner where the spell's coverage dipped. It wasn't perfect—but it worked. No alarm. No lights. Just silence.
He turned, beckoning the next group.
One by one, they passed through, each breath held like it might be the last. When the last two crossed safely, Saint Martha let out a quiet exhale beside him. "We're not out yet."
They kept going—twisting through cold, reinforced halls that smelled like metal and ash. But their pace slowed. One of the older humans, an older woman with a bandaged leg, had fallen to her knees.
"I… I can't," she whispered, shaking. "I can't keep up."
"You can," Ren said, crouching beside her. His tone was gentle but resolute. "We're almost out. Just a few more halls. You've made it this far—you've already survived more than they expected."
She looked at him, trembling. "You don't even know me. Why do you care so much?"
Ren offered her a small smile. "Because I do. That's enough, right?"
Her eyes filled with tears, but she nodded.
Another soldier took her arm. "Come on. We've got you."
They moved again—slower, but steady.
And then Martha's voice came, soft but edged with something deeper. "Where's Jeanne?"
Ren's stride faltered for just a breath. Then he looked back at her. "She's still inside. Another chamber. Locked down harder than anything else I've seen."
Martha stopped. "Then why are we the ones you're rescuing first?"
"I went to her first," Ren said. "I found her. But she told me to get you all out first. Said the moment I try anything near her, alarms will flood the place. If we're caught… there won't be a second chance."
A beat of silence passed. The group stared at him—some wide-eyed, others confused, but Martha... she understood. She swallowed tightly.
"She told you that herself?"
Ren nodded.
Martha closed her eyes, then looked back at the others. "Then we trust her. We trust him. We keep moving."
They reached the final corridor.
The cold night air leaked in through the seams of the final blast door ahead—freedom was close enough to smell. Ren's Third Eye pulsed once more—no movement outside. Not yet.
He turned to the group. "We're here. The exit's just beyond this door. Go left and into the ravine. There's someone waiting there—Charlemagne. You'll be safe with him."
"What about you?" one of the AI asked, limping up beside Martha. "Aren't you coming with us?"
Ren's hand clenched at his side.
"No," he said, voice quiet but steady. "I'm going back."
Martha's expression tightened. "You're not serious."
"I am," Ren said. "She's still in there. I promised her."
"You won't get back in that easily," a soldier warned. "The patrols will change soon. You won't even make it past the first hall."
"I'll manage," Ren replied. "I have to."
The group murmured among themselves—concerned, unsure.
Martha stepped closer. "Ren, you've already done more than anyone could ask for. You don't need to throw yourself away—"
"I'm not," he interrupted, meeting her gaze. "I'm trusting you to get them out. That's how we win. One step at a time. If you wait for me, you risk all of that. So don't."
Her lip trembled slightly, but she caught herself. Then nodded.
Ren's smile was faint but full of warmth. "Tell Charlemagne I'll bring her back. One way or another."
He turned back to the blast door and keyed it open. Cold air surged in, and night blanketed the ruined landscape outside.
"Go," Ren said softly. "Now."
The group started to move, helping each other through the breach—AI holding humans, humans supporting limping androids, tired feet pushing forward on sheer will.
As Martha passed him, she rested a hand briefly on his arm. "We will be waiting for you in the base."
"I will," Ren promised.
And then he disappeared back into the dark.
The war table flickered in dim holographic blue, casting long shadows across the steel walls of the underground command center. It was late—too late for new reports. And yet, a low-priority alert blinked persistently on the corner of the screen, drawing Rin's eyes like a splinter she couldn't ignore.
She sighed, fingers pinching the bridge of her nose as she walked over. She hadn't slept in nearly twenty hours, and her coffee had gone cold hours ago. The last update from the field said Ren and Charlemagne had begun their infiltration—quietly, cleanly.
They were supposed to be ghosts. In and out. No heat. No complications.
She tapped the blinking alert.
The screen flared to life, displaying the aerial feed from a reconnaissance drone stationed in low orbit. Most of the readings were static or background anomalies—but then it came into focus.
A massive shadow eclipsed the landscape.
A floating fortress, imperial and immaculate, with golden lines etched into black steel. Carolus Patricius.
Her breath caught.
"...No," she whispered.
The fortress hovered above the very coordinates she had marked just a day ago—the base near the ruins of Fuyuki Park. The place she sent them. Her heart lurched.
This wasn't part of the simulation.
She hurriedly pulled up movement logs. The fortress hadn't been detected leaving Karl's usual territory. No warning. No build-up. It had just... appeared. A calculated move. Precise. Tactical.
"Karl himself is there…" she muttered, her voice barely audible.
Her hands moved faster now, dragging in side panels, triangulating signals. A presence that massive couldn't go unnoticed. She checked magical energy readings—spikes were everywhere. Powerful signatures, layered atop one another.
Two. No—three Servants. One of them unmistakably Karl der Große. The other two were unidentified, but the intensity of their readings was off the charts. One of them felt... sharp. Lethal.
She swallowed the rising panic. Her fingers hovered over the comms terminal—but she stopped.
Ren and Charlemagne had no direct line.
That was part of the protocol. To protect them from being tracked.
Rin slammed her fist against the table.
"Damn it."
A nearby technician flinched but wisely stayed silent.
She took a deep breath, forcing herself to think. How much time had passed since the mission began? Had they already gotten the prisoners out? Were they still inside? No answers. Just flashing numbers and static feeds.
Rin straightened, her voice suddenly clear and cold.
"Divert all recon drones to Fuyuki Sector," she ordered, loud enough to be heard across the command room. "Now. I want real-time data on that fortress. Check for evacuation signals or magic bursts. Anything that stands out. Have our combat squad ready at any moment."
One of the operators, a young woman with wide eyes, hesitated. "Do you think they're still in there?"
Rin's jaw clenched.
She didn't answer right away. Her heart said yes. Her instincts screamed no. But her voice came out steady.
"I don't know," she said. "But we're going to find out."
The room fell into silence, only the quiet hum of machinery filling the air.
She stared at the live image of Carolus Patricius, floating like a god's judgment over the battlefield, and felt the weight of every decision she'd made bearing down on her shoulders.
Please... please let them be out already…
The scene ends with Rin standing before the screen—small, determined, and utterly alone with the knowledge that something had gone horribly wrong.
The restraints hissed open with a final click.
Ren stood beside Jeanne, the last of her bindings released. She remained silent, flexing her fingers to chase the numbness away, her breathing still labored from whatever method of containment they'd used. He didn't press her to move yet. They both needed a second.
Then the hum started.
A low pulse beneath the floor. A sound Ren hadn't heard since entering the base — different from the machinery, deeper than the alarms. It vibrated through his boots, through the air itself.
Jeanne's head snapped up. "Something's coming."
Ren didn't answer. He already knew.
The chamber's massive doors began to open. Cold white light spilled through the widening gap, casting long shadows across the ruined walls. Three silhouettes emerged, framed in that artificial glow like figures stepping out of another world.
The one in the center wore white and gold — dignified, towering in stature, his calm presence more suffocating than rage. One side of his cloak was fastened with a cross-shaped clasp. A symbol of empire.
Ren didn't need a nameplate. He recognized that man from Rin's files.
Karl der Große.
Behind him walked two others. One — a man draped in regal robes; eyes hidden behind the glint of a golden monocle. The other — a woman whose presence felt sharp enough to cut through steel, her crimson cloak trailing behind her like fire. Neither spoke. Neither needed to.
They were weapons.
Karl's gaze swept the chamber, lingering on Jeanne for a moment before landing on Ren.
"You're far from where you belong."
Ren shifted, subtly placing himself between them and Jeanne. "You knew I was here?"
"I suspected someone would come," Karl said. "But not someone like you."
He took a few steps forward. Each one echoed louder than the last. Jeanne moved to rise, but Ren gently gestured for her to stay back. Her safety came first.
Karl studied him — not like a man viewing an enemy, but like a scholar examining an unfamiliar equation.
"You present as a Servant," he said, "but the data disagrees. You have form, cohesion, presence… yet none of the categories apply."
Ren held his ground. "Maybe your system's just out of date."
That earned a small pause — almost amused. Karl tilted his head.
"Your signature reads like a closed circuit. Internalized energy flow. Gained strength independent of a Master or Command System. Progression in phases. Growth through action. All remarkably structured."
A beat of silence.
"I've seen that structure before. Not designed by Seraph. Not natural. But certainly... deliberate."
Jeanne looked at Ren, confusion flickering behind her eyes.
Karl continued, tone steady and merciless: "You're not the only one with this kind of power. There were others. Aberrations — entities shaped by something else. Something that mimics divine order, but functions by its own logic."
He stepped closer.
"I have removed them. Just as I will remove you."
Ren didn't speak. He didn't flinch. He knew this kind of man — not a tyrant consumed by emotion, but one who believed in removal as necessity. Karl wasn't angry.
He was cleansing.
A subtle shift from the cloaked figure to Karl's right.
It was all the warning Ren got.
In a blur, something moved. A red shimmer. Steel caught the light.
He barely had time to turn.
The spear pierced through his chest, straight into the heart.
No shout. No roar.
Just silence — and Jeanne's gasp as Ren staggered.
His breath caught, vision flaring white. Then red.
His knees gave way, body collapsing into a heap beside her. Jeanne caught him instinctively, her arms trembling as she pulled him close.
His blood spilled across the floor.
Karl's voice was the only sound left in the chamber.
"The system corrects itself."
The lights flickered overhead. Jeanne stared up at Karl, her hands soaked in Ren's blood, her breath shaking, her mind reeling.
And Ren…
…didn't move.
Author's Note: A quick changelog, I put a header on all existing chapter because I felt like my summary is quite lacking.
Anyway Thank you for all the support! See you soon~
