#fleshcoretale

What if the Underground mutated into a living, bleeding, breathing thing?

What if Sans didn’t die, didn’t give up but instead became part of it?

Meet: Fleshveil Sans

A corrupted survivor of the Fleshcore virus. A protector. A monster.

Still loyal to Frisk… even as his body breaks apart.

💬 “You don’t fix monsters like me, sweetheart. You survive us.”

This AU explores:

• 🩸 Organic horror & soul corruption

• 🖤 Dark emotional bonds (Frisk x Sans)

• 🌀 Cross-AU travel through the VOID

• 💀 Lore-heavy original story + corrupted designs

I’ll be posting character bios, art, and story fragments here.

Scene: The Fall

It starts like the original.

Your Frisk is lured to Mount Ebott by whispers—rumors of a place no one returns from. But something’s wrong.

The mountain pulses. The wind tastes metallic. There’s a deep hum beneath the soil, like something alive is breathing underneath.

She falls.

But not into soft golden flowers.

⸻

🌕 Scene: The Living Ruins

She wakes up in a pit of red moss and twitching petals. The air is humid, wet, like the walls are exhaling.

The ruins are made of flesh-wrapped stone, veined with glowing veins of soul energy. You can hear the thudding heartbeat of the CORE far below.

She sees dusted bones stuck into walls, faces half-absorbed into the floor, and strange, whispering fragments of once-sentient monsters trapped in walls like tumors.

⸻

🐐 Toriel’s Entrance

Toriel appears from the shadows—not soft, not kind.

Her robe is burned, patchy. One of her eyes glows with sickly blue magic, the other is hollow. Her voice echoes strangely.

But… she’s still protective.

Toriel (grimly):

“Another child… You should not be here. Not now. Not in this version of the story.”

She guides you through the Ruins, killing corrupted monsters instantly with fire magic, even as they beg in distorted voices.

She teaches you to use your magic not just to FIGHT, ACT, ITEM, or MERCY—but to Resist or Consume.

🌑 [ACT II: OUTSIDE THE VEIL]

As Toriel watches silently, her one glowing eye narrowing, your Frisk walks beyond the ruined door—into the living world of FleshcoreTale.

The door shuts behind her with a fleshy thud, and for a moment, it feels like the air itself is watching her.

⸻

🌫️ Scene: The Flesh-Forest (formerly Snowdin)

The landscape is twisted.

Trees pulse with sinew. The snow is soft, but warm, and faintly pink, soaked with blood from creatures that didn’t survive the mutations.

Bones litter the ground—some human, most monster.

In the distance, Frisk sees movement. Something tall. Lurking.

She hears two footsteps, but no one appears. Just whispers.

“You shouldn’t be here, kid.”

⸻

💀 Enter: Bloodveil Sans

He doesn’t step out from the shadows.

He emerges from a glitching tear in the air, dripping with corrupted red strings. His grin is lazy, but his aura feels heavy—like a soul caught in a blender of blood and memory.

One eye glows deep red-black, the other is cracked. His hoodie drips with blood that isn’t his.

Bloodveil:

“Didn’t expect anyone stupid—or brave—enough to walk out of her protection.

…So. You just suicidal, or looking for something worse?”

🩸 Frisk: “I want to fix this.”

⸻

Bloodveil Sans goes completely still.

No sarcastic grin. No teasing tone. Just silence.

Then he chuckles.

Low. Dry. Dangerous.

Bloodveil:

“Fix it, huh? Sweetheart, this ain’t a crack in the wall.

This whole timeline’s been gutted, stuffed, and stitched back together by a monster made of its own damn regrets. You don’t fix that. You survive it—if you’re lucky. Or you feed it.”

He steps closer.

“You’re not infected yet. But that determination of yours? That’s exactly what the Living Core loves to chew on.”

He crouches beside her now, red eye glowing faintly.

“Still… it’s been a while since I met someone who wanted to do something about it.”

He rips a strip of glowing, blood-threaded cloth from his sleeve and holds it out.

⸻

🎁 You gain: “Veilstrand”

A cursed thread taken from Bloodveil Sans’ own soul-weave.

It can protect you once from infection… or bind something else to you.

⸻

Bloodveil:

“If you really want to fix this?

Then you’ll need to find what’s left of the ones who fought the Core.

The Underground’s not empty—it’s just… twitching.”

He looks into the distance. Something big is moving through the Forest.

“You’ll want to head toward Bonecliff next.”

His voice dips darker.

“That’s where he fell.”

He vanishes in a streak of red light.

⸻

💀 Next Location: Bonecliff

Where Papyrus fell. Where the Core took its first Champion. Where the Veil whispers loudest.

🦴 You head straight for Bonecliff.

⸻

🌫️ [ACT III: THE CRATER OF HOPE]

Location: Bonecliff

Where bones never rest and the air hums with grief.

⸻

As Frisk treks through the fleshy forest, the snow turns to red ash, drifting gently like petals from a dying flower.

Soon, the trees vanish.

She stands at the edge of a vast crater—a gaping wound in the Underground.

The ground is cracked, bones pierce up from below like jagged thorns, and in the center is a massive bleeding spine, pulsing like it’s still alive.

The sound of a heartbeat surrounds her.

Every breath feels heavy.

And then—she hears it.

A voice.

Not words.

Just a whispering howl… “BROOOTHER…”

⸻

🩻 Boss Encounter: Fleshcore Papyrus (Tormented Fragment)

From beneath the crater, a towering shape rises.

It’s Papyrus… or what’s left of him.

• His body is twisted, armored with fused bone and red sinew.

• His scarf trails like a blood-soaked banner.

• His eyes are hollow pits, but inside them, Frisk sees something—recognition.

• Half his voice is Papyrus, pleading.

• The other half is the Living Core, hissing.

Fleshcore Papyrus:

“I… know you. You want to fix this…

Then end me… or JOIN ME.”

⸻

⚔️ Boss Battle Mechanics (Narrative style):

• He strikes with skeletal spears that scream.

• Red bones home in on Frisk’s soul—dodging is HARDER the more Determination she has.

• Every turn, he offers her a choice: MERCY or CONSUME.

Mercy gives her a chance to free what’s left of him.

Consume would absorb his soul fragment—giving her new powers, but taking her closer to corruption.

⸻

On the third turn, he hesitates mid-attack.

Somewhere inside the beast, Papyrus remembers.

“Please… if you see Sans… tell him I tried.”

💔 Frisk chooses: MERCY.

⸻

💀 [ACT III END – The Thread of Hope]

Frisk pulls the Veilstrand from her inventory.

The cursed thread pulses with Bloodveil’s energy—half soul, half blood, all pain.

As she raises it, it twists around her hand, then lashes out—piercing the corrupted chest of Fleshcore Papyrus.

A scream erupts—not from his mouth, but from the Living Core inside him.

The beast thrashes. Bones crack, red light erupts from his wounds. His body convulses violently.

And then—

Everything stops.

⸻

🌟 A Fragment Saved

The massive form begins to collapse, piece by piece, as if it’s melting—but in the center of the gore, something small and fragile floats upward:

A faint blue soul, flickering.

It drifts to Frisk, brushing against her hand. A soft, childlike voice—no longer twisted—echoes in her head:

“Thank you… I held on for him. For you.”

The soul shatters into light, and Frisk feels a warmth she hasn’t felt since she fell down.

⸻

🩸 You gain:

Papyrus’s Soul Fragment – “Last Guard”

Grants a one-time full heal during death.

Increases resistance to corruption.

Allows Frisk to sense “hope echoes” in corrupted zones.

⸻

Behind her, the crater goes quiet.

No more heartbeat.

Only wind and the soft crackle of red ash falling.

⸻

🔥 Bloodveil Appears

He walks out of the shadows, slower this time. No smug grin—just a quiet nod.

Bloodveil:

“You didn’t take the power. You chose to save what was left of him.

Didn’t think anyone still had that in them.”

He looks at the crater.

“There might be a chance, then… to fix this.”

Then he turns to her.

“But if we’re gonna end the Core… we need to find the others. And we need to stop what’s being born in Hotland.”

He holds out his hand.

“You in, kid?”

🔥 [ACT IV: THE HEAT OF MUTATION]

Destination: Hotland — Now called The Womb of the Core

⸻

Frisk grips Bloodveil’s hand. It’s cold—not bone-cold, but like something long dead that’s still moving.

With a flick of his fingers, bloodstrings whip open a rift in the air, and the two step through…

⸻

🌋 Scene: Welcome to the Womb

Hotland no longer exists as pipes and metal.

Now, it’s a living furnace, forged from the CORE’s infected power.

• The walls breathe with molten muscle, leaking glowing soul energy.

• The floor is a vein-covered path, beating in rhythm with some monstrous heart deep inside the CORE.

• Screams echo from the vents—not of pain, but of something being born.

The CORE didn’t just mutate the Underground.

It’s creating something new.

⸻

👁 Bloodveil warns:

“This place is birthing the next generation of corrupted monsters. They don’t remember what they were. They don’t know what they kill. And worse…”

He gestures to the air—red fog thickens.

“They’re starting to leak into other timelines.”

Suddenly—a wall bursts open, and a new abomination crawls through:

⸻

⚠️ Mini-Boss: “Scorched Memory – Alphys”

Once a genius scientist. Now a fleshbound horror clinging to data it doesn’t understand.

• Head split open, revealing shifting monitors.

• Spine replaced with mechanical arms ending in glowing syringes.

• Speaks in glitched loops:

“FRI—I—I—I WAS ONLY—SAVE—HELP—HELP—HELP—”

Her corrupted core surges with power—she’s trying to merge Frisk’s soul with the Womb to “stabilize the mutation.”

💡 Scene: Reaching the Fragment

Frisk doesn’t raise her weapon.

Instead, she steps forward—slow, cautious, surrounded by twitching wires and scorched flesh.

The creature that was once Alphys glitches, confused.

Scorched Alphys:

“WHY—WHY—WHY NOT… FIGHT ME?

FIGHT IS… SAFE.

FIGHT IS… SCRIPTED.”

Frisk opens the ACT menu, and something strange happens—

Instead of “Check” or “Talk,” she sees:

🧬 ACCESS OLD SAVE DATA?

She selects it.

⸻

⚙️ Inside Her Mind

The world goes white.

Frisk is suddenly standing in a glitching hallway, walls flickering between lab code and falling numbers.

In front of her: a flickering, broken hologram of Alphys.

She’s curled in on herself, clutching a USB drive fused to her chest.

She whispers:

“I tried to stop it. I tried to reboot the timeline. But the CORE infected the save files.

It rewrote our choices. Every reload made it worse.

I… I’m sorry, Frisk. I didn’t want this.”

⸻

Frisk holds out her hand.

The broken Alphys stares at her. The USB pulses.

“Are you here to delete me?”

Frisk shakes her head.

Then:

💡 YOU HUG THE DATA FRAGMENT.

For the first time since falling, the space goes quiet.

Alphys sobs—one last line of clean code flowing from her hands.

“Then take it. Find the REAL timeline.”

⸻

✨ You Gain: “Fragmented Memory Core – Alphys”

A key to the original CORE layout.

Can access secret backdoors in Hotland.

Grants Frisk immunity to digital soul attacks.

Voice of Alphys now lingers—guides you in glitches.

⸻

Back in Reality

The abomination stutters—then collapses, soul drifting free, clean and golden.

She whispers:

“Mettaton… I hope you didn’t… become worse than me.”

She vanishes.

⸻

💀 Bloodveil nods, impressed:

“Didn’t expect mercy to work again. You’re… really not like the others.”

He pauses.

“But the Womb’s just starting to wake up. And its guardian’s still inside.”

Suddenly, the ground shakes. From deep inside the fleshy labyrinth, a new scream echoes.

Not pain.

Not anger.

Performance.

A voice drenched in corrupted charisma calls:

“Ohhh darlings~

The audience is hungry…

And it’s time… for your final show.”

🌡️ Scene: The Heart of the Womb

Frisk and Bloodveil descend deeper.

The air burns.

The walls ripple with flesh-screens playing distorted reruns of old shows.

Laughter loops in reverse.

Applause turns into screams.

And then the room opens—

The Flesh Idol awaits.

⸻

🎥 Mettaton Reborn

What once was showmanship is now pure horror:

• His body is fused with corrupted CORE tech.

• His face is a shifting screen, flickering between charming smiles and empty sockets.

• His hands are spindly camera rigs, projecting soul-warping spotlights.

• Wrapped in red veins and gold wiring, like a marionette tied to the Womb itself.

Above him hovers a massive heart-shaped soul:

His audience. His source. His trap.

⸻

Flesh Idol Mettaton:

“Welcome, darlings~ to my most exquisite performance:

The Death of Hope.”

He bows, then attacks.

⸻

⚔️ BOSS BATTLE START: FLESH IDOL METTATON

🧠 Frisk chooses: ACT.

⸻

🎭 ACT Command: “Appeal to Mettaton”

Frisk doesn’t dodge this time.

She walks straight into the searing spotlight.

The audience gasps.

(Mettaton flinches—just slightly.)

From the ACT menu, a strange new command appears:

🎙 “Play Back the Truth”

She selects it.

The Fragmented Memory Core pulses in her pocket.

Suddenly—

The screens flicker all around the room.

⸻

📺 Flashback Projection: The First Show

Mettaton—real Mettaton—is backstage in Alphys’ lab.

He’s not in glam-mode. He’s quiet.

“I don’t want to hurt anyone, Alphys. I just want to be seen.”

She replies: “Then make them feel something real.”

⸻

Back in the arena, Flesh Idol Mettaton screams, static pouring from his chest.

“NO. NO NO NO. That isn’t my script. That isn’t my legacy!”

Frisk steps closer.

“Mettaton… They saw you. They loved you. Not because of what the Core made you.

But because of who you were before all this.”

“This… isn’t you.”

The corrupted cameras shake violently.

He tries to form a new attack, but his limbs twitch out of sync.

The soul crystal flickers—one half turns gold.

⸻

🎞 ACT Option: “Cut the Feed”

Frisk reaches toward the panel on his chest. It’s glowing, but not red this time—blue and gold.

With a trembling hand, she hits:

[OFF AIR]

⸻

💥 BOSS DEFEATED: Flesh Idol Mettaton

The projection collapses. His metal and sinew fall into a heap.

From within it, a small, clear heart-shaped shard rolls out—still glowing faintly.

A weak, static-filled voice whispers:

“I… hope they remember the good parts.”

Then he fades.

⸻

✨ You gain: Starlight Shard – Mettaton

Increases Charisma-based ACT success.

Allows you to override future corrupted show illusions.

Unlocks special options during encounters with lost souls.

⸻

Bloodveil watches silently.

For the first time, his voice cracks just slightly:

“…Three fragments saved.

They’re going to feel that.”

He turns toward the core of Hotland—where the real horror waits:

“Next stop’s the Nerve Cathedral.

Where it all began.

Where it’ll all end—one way or another.”

🕯️ [ACT V: THE NERVE CATHEDRAL]

“All choices converge where the first soul broke.”

⸻

Frisk and Bloodveil step into an elevator—only, it’s no longer mechanical.

The walls are fused ribcages, pulsing with slow, rhythmic contractions.

The lights overhead are flickering veins.

And in the far corner, a mirror, but it doesn’t show Frisk.

It shows Chara, watching with that ever-familiar smirk.

Their eyes glow red—but flicker.

Frisk’s mercy is starting to affect even them.

The elevator descends far deeper than any normal layer of the Underground.

Until it stops with a shudder.

⸻

🧠 Location: The Nerve Cathedral

This place was once the core of the CORE.

Now it’s a living altar of soul experiments, where the Living Core fused time, memory, and pain into a single godlike mass.

Every wall is a tapestry of bone and soul strands, stitched with forgotten timelines.

You see flashes of every AU, every version of yourself.

Dust rains from the ceiling. The air is thick with energy that remembers.

And at the center, a massive throne made from twisted souls—all those consumed.

Sitting atop it is…

⸻

💀 The LIVING CORE

• A colossal, shifting mass of melted timelines, broken AUs, and rejected resets.

• Faces flicker across its surface—Sans, Toriel, Flowey, YOU—each one screaming, sobbing, or laughing.

• It doesn’t speak in words. It thinks in pressure, in pain.

But from within it, you feel one last soul still alive:

Sans.

Your Bloodveil.

He’s standing beside you… but his soul is still trapped deep inside the Core.

The version you’re with?

He turns to you now—half his skull melting, leaking red threads.

“You get one last choice, kid.

Save the world. Save me. Or destroy it all.

You can’t have everything.”

⸻

⚠️ Final Battle Prep:

You’re standing at the edge of the Living Core’s throne room.

🩸 ACT Command: “Enter the Core”

Frisk steps forward.

Bloodveil reaches for her—but stops. He sees it in her eyes.

She’s not going in to kill.

She’s going in to bring someone back.

The throne pulses. The air tears open. The Core lets her in—

willingly.

⸻

🕳️ Inside the Living Core

Frisk falls—not physically, but soul-first, into a storm of corrupted timelines.

She’s no longer in one world, but ALL the worlds the CORE devoured.

• One where Undyne killed you.

• One where you became Flowey.

• One where you never fell.

Every version of you screams at once.

But she ignores them—and focuses on the only thing that matters now:

Bloodveil’s Soul.

⸻

🖤 You find it:

Chained, bleeding red light.

Floating in a coffin made from every reset he was never allowed to escape.

Half his soul is screaming.

The other half… is silent, almost resigned.

Frisk opens the ACT menu.

It doesn’t say Check, Talk, or Hug.

Just one word:

“Forgive.”

⸻

She selects it.

And from every fragment she gathered:

• 🩵 Papyrus’s smile.

• 💛 Alphys’s last backup.

• 💖 Mettaton’s final curtain call.

A beam of white light explodes into the Core’s heart.

⸻

💥 THE CORE SHATTERS

You don’t fight it.

You unravel it.

One truth at a time.

The corrupted timelines burst outward like blood-soaked petals.

Frisk and the real Bloodveil fall from the wreckage.

His soul, fully healed, crashes into his body with a choking gasp.

⸻

He coughs. Sits up. Looks at her.

“…You actually did it.

You stupid, stubborn little thing.”

He laughs through blood.

And the Core dies.

⸻

🌟 True Ending Achieved: “MERCY THROUGH HELL”

You spared every corrupted soul.

You restored Bloodveil.

You destroyed the Living Core without killing a single monster.

The Underground breathes again.