The first thing Aiden noticed when he woke was the sound.
A low, rhythmic pulsing, like a heartbeat buried beneath the stone.
Thump… thump… thump…
It wasn't his heart — at least, he hoped not. His chest rose and fell too fast for that slow, heavy rhythm. The cavern around him glowed faintly, veins of blue light pulsing through the black stone walls, like the dungeon itself was alive.
He sat up slowly, groaning. "Right. Fell into a collapsing tunnel. Probably died. Again."
> [System Notice: You are still alive. Somehow.]
[HP: 27%]
[Status: Bruised Ego (Severe)]
"Yeah, thanks," he muttered, rubbing his temples. "Always nice to have moral support from a piece of broken code."
The air was damp and warm, carrying a metallic scent that made his tongue taste like blood. Drops of water trickled from the ceiling, echoing softly. But beneath that… that heartbeat persisted. Faint. Ancient.
Then, a whisper.
Not a sound, but a feeling—a ripple through his mind.
> "...child of two worlds…"
Aiden froze. "What the hell?"
His System didn't respond this time. No witty notifications. No sarcastic pop-ups. Just silence.
He stood, dusting off his torn shirt, and raised his flickering torchstone. The cavern stretched endlessly, a twisting maze of shadow and faint light. But ahead, carved into the ground, was something impossible — a circle of runes that pulsed in time with that mysterious heartbeat.
And at its center floated a crystal, no larger than his hand. It radiated warmth… and danger.
---
He approached cautiously. "Alright. Classic setup. Glowing magic rock in creepy dungeon. What could possibly go wrong?"
> [System Warning: Unknown Mana Signature Detected.]
[Estimated Power Level: ???]
[Recommendation: Run.]
Aiden smirked faintly. "You always say that."
When his fingers brushed the crystal, the world snapped like glass.
---
For a moment, there was nothing. No air. No ground. Just a rush of memories that weren't his — flashes of fire, war, and a sky split by lightning. He saw people kneeling before a massive shadow, a god-like being whose eyes burned with endless rage.
Then — a voice. Female. Soft, sorrowful.
> "So it found you… my last fragment."
Aiden gasped as he stumbled back into reality, clutching his head. "Who… who are you?"
> "I am what remains of the Dungeon Core… and you, Aiden Cross, are standing in my grave."
The crystal pulsed once, like a heartbeat matching his own. The cavern trembled around him.
---
Dungeon Core.
He'd heard that term before — whispered by adventurers in the guild hall, talked about like legends. The living heart of every dungeon. They said if you destroyed one, the dungeon collapsed. If you absorbed it… you could become something beyond human.
Aiden's throat went dry. "You're saying this place—"
> "—is dying," the voice interrupted gently. "The gods who built it have long forgotten their creations. I linger only because my essence clings to this broken shell. But you… you're not supposed to be here."
He laughed weakly. "Tell that to the System. It's got a terrible sense of direction."
> [System Notice: Insult registered. Processing emotional damage…]
[Processing failed.]
[Error: I am not your therapist.]
Despite himself, Aiden chuckled. "Guess not."
The voice — the Core — grew quieter, like fading echoes in a dream.
> "Your presence disturbs the balance… yet something within you resists destruction. You carry a piece of code that even the gods do not recognize…"
"Code?" His stomach tightened. "You mean my System?"
Silence. Then, a whisper that chilled his bones.
> "Not your System. The original one."
---
The walls shuddered. Cracks ran up the glowing veins of stone. The crystal flared bright — blinding — and Aiden stumbled backward as the ground caved beneath him.
> [Emergency Protocol Engaged.]
[Teleportation in progress — Destination: Safe Zone 3-B.]
[Warning: Mana Overload detected.]
"Wait—what—"
The world shattered again, hurling him into darkness.
---
When he awoke, he was lying on soft grass.
Grass. Not stone.
Sunlight filtered through golden leaves above him, warm and gentle. Birds sang somewhere nearby, and the faint rush of water filled the air. It was… peaceful.
Too peaceful.
> [System Notice: You have exited the dungeon.]
[Achievement Unlocked: "Grave of the Core."]
[Reward: ??? (Processing error)]
[New Quest Unlocked: Find the Source of the Voice.]
"Figures." Aiden sat up, squinting. "Even when I win, I get error messages."
He stood, stretching sore limbs. His clothes were torn, his hands scraped, but somehow he was alive. The forest stretched endlessly around him, vibrant and unreal, like a painting come to life.
Then he noticed something else — a girl sitting on a rock a few meters away, staring at him.
Long silver hair shimmered under the light. Her eyes were the color of twilight, and her clothes — though tattered — hinted at noble origins. She held a staff that looked far too heavy for her small frame.
When their eyes met, she blinked. "You're… alive?"
Aiden gave a half-smile. "Surprisingly, yeah. You?"
She tilted her head. "I thought you were a corpse the dungeon spat out."
"...Wow. Thanks for the vote of confidence."
> [System Suggestion: She might be dangerous. Try not to die flirting.]
[HP: 42%]
He ignored the message. "Name's Aiden. You are?"
"Lyria." Her tone softened slightly. "You shouldn't be here. This part of the forest belongs to the Hunters."
"Hunters? You mean… monsters?"
"No." Her gaze turned cold. "People."
---
They walked together — or rather, she walked ahead while he tried to keep up. She moved with quiet grace, her steps barely touching the ground, like someone who'd lived in this world far longer than him.
Along the way, she glanced at his System interface, which flickered faintly beside his shoulder. "That symbol… I've seen it before."
"You can see it?" Aiden blinked.
"Barely. It's… old magic. Forbidden, I think." She hesitated. "Most Systems are fragments of divine code. But yours feels different. Wrong."
He frowned. "Wrong how?"
She didn't answer. Instead, she stopped at the edge of a cliff overlooking a valley filled with ruins — ancient towers swallowed by vines, half-buried statues, and the faint glimmer of energy pulsing beneath the ground.
"That's where the Hunters live," she said quietly. "If they see your mark, they'll kill you."
"Noted," Aiden murmured. "So… any chance they're friendly?"
Her look said everything.
---
They set up camp near a stream that night. Lyria built a small fire, her hands trembling only slightly as she lit it with a spell — Ignis Minor. A soft flame blossomed from her palm, bathing her face in gold.
Aiden watched her, curious. "You use mana directly. No System interface?"
She nodded. "We don't rely on gods or their code. Power that isn't earned corrupts the soul."
He smiled faintly. "Guess that explains a lot about me."
Something in his tone made her glance up. "You've lost people," she said quietly.
He looked into the fire. "I've lost… myself."
For a moment, there was silence between them — not awkward, just heavy. The kind that fills the spaces words can't reach.
Then, without warning, the fire flickered.
The forest grew cold.
> [System Alert: Unknown Entity Detected.]
[Warning: Stealth-class Beast approaching.]
Lyria's staff glowed faintly as she stood. "They've found us."
Aiden rose to his feet, heart pounding. His System flickered erratically, trying to form a weapon. For once, it succeeded — half-summoning a crude blade of unstable light.
He grinned nervously. "Hey… progress!"
"Less talking," she hissed, eyes narrowing at the shadows between the trees.
The air grew thick. Then — movement.
Something fast. Too fast.
A blur lunged from the darkness, claws flashing.
Aiden barely raised his weapon in time. The impact sent him sprawling, the System blade shattering like glass.
> [Weapon durability: 0%. You're screwed.]
"Not helping!" he shouted, rolling aside as another claw ripped through the air.
Lyria chanted something, her staff blazing with silver fire. A bolt of light struck the creature, revealing it — a massive, wolf-like beast made of shadow and bone, its eyes burning crimson.
It roared, the sound shaking the forest.
Aiden swallowed. "You take the front. I'll… cheer from the back?"
"Move!" she snapped, hurling another spell.
The battle was chaos — light, shadow, and the echo of roars. Aiden stumbled, dodging claws by inches, every breath filled with adrenaline and terror. But then, something inside him clicked.
The System flickered again.
> [Adaptive Protocol Activated.]
[Skill Acquired: Shadow Counter Lv.1]
He didn't think — he just moved. The next time the beast lunged, he sidestepped instinctively and struck.
A surge of black energy exploded from his arm, piercing the creature's chest.
It howled — then dissolved into mist.
Silence fell.
---
Aiden stood panting, his body trembling. "Did I just—"
"Yes," Lyria breathed, eyes wide. "You absorbed its essence."
> [System Notice: Skill evolved — Shadow Counter → Devour Echo Lv.1]
[Caution: Compatibility uncertain.]
The ground pulsed faintly beneath them — a familiar rhythm.
Thump… thump… thump…
Lyria turned pale. "That sound… the Dungeon Core. It's following you."
Aiden stared at the darkness beyond the trees.
It wasn't over.
---