─────────────🕳️ NM!Gaster: "The Shattered Mind of the Abyss"
👁️ Overall Aesthetic
Silhouette: His tall, humanoid frame is thinner, almost skeletal, stretched unnaturally as though partially unraveling. His limbs elongate and taper, fingers unnaturally long and jointed like puppetry strings, twitching with an insectile eeriness.
Posture: Slightly hunched, as though the weight of infinite realities is pressing on his back. His head tilts often at uncanny angles.
🧠 Head & Face
Skull-like head, retaining the blank eye sockets, but now one is cracked open, leaking a viscous inky black fluid (nightmare matter). The other eye is hollow and flickers with shifting void sigils.
Jaw slightly dislocated; when he "speaks," it unhinges further, revealing a black swirling void, sometimes with faint whispers escaping.
Fractures run along the head, glowing faintly with pale blue and sickly purple—a sign of the paradoxical magic keeping him together.
👔 Attire
Tattered black lab coat, now mutated by the void—its fibers move as if alive. It's sleeveless on one side, burned away by dimensional erosion.
A high collar, stitched together by interdimensional thread (shimmering like starlight), frames his neck.
Underneath, a deep indigo vest, inscribed with cryptic symbols—some flicker between legibility and nonsense.
Chains wrap around one arm and torso, not for restraint, but as anchors to dimensional stability—some links float in mid-air, unattached.
🖐 Hands
Fingers are abnormally long, ending in faintly glowing, void-black claws.
The palms have circular glyphs, etched into the skin—each activates when he summons his Nightmare Blasters or corrupts space.
His right hand constantly trembles, unable to contain the unstable energies of the nightmare void.
💀 Nightmare Elements
Gaster Blasters are now twisted: resembling dragon skulls with elongated, broken horns and screaming mouths instead of smooth bone.
Their beams appear as negative light, draining the color and sound from the environment instead of emitting energy.
Tendrils of darkness trail from his body—like ink, they slither behind him, sometimes forming hands or faces of lost souls whispering warnings.
Clockwork motifs occasionally flicker into view behind him—representing broken timelines, frozen or ticking in reverse.
Butterfly-shaped runes, glitching like corrupted data, orbit his back. When he uses powerful magic, they spin rapidly and tear at reality.
🎤 Voice / Sound
Speaks in glitched, layered whispers—multiple voices out of sync, echoing like they were spoken across dimensions.
Every word seems to bend the air around him, like language that wasn't meant to be heard.
His footsteps don't make sound—they remove sound, creating a pocket of eerie silence.
🌌 Powers & Effects
Reality Erosion: Enemies near him start to have pieces of themselves glitch out or lose cohesion.
Dimensional Drift: He appears to teleport, but in fact "slips" through cracks in space.
Memory Corruption: His presence causes nearby characters to forget things or misremember timelines.
Gaster Glyphs: Floating, glitching sigils that act as wards, traps, or narrative triggers.
🖤 Color Palette
Base skin: Ash white with cracks and void exposure.
Clothing: Deep void black, purples, and indigoes with subtle, starry texture.
Energy glow: Pale blue (classic Gaster), contrasted with sickly purples and shifting glitch tones.
───────────🩸 NM!Dust Sans: "The Harbinger of Fractured Mercy"
🧍 Overall Aesthetic
Physique: Thinner than normal Sans, almost emaciated. His hoodie and body sag, as if he's partially decayed or collapsing inward.
Posture: Slouched, dragging a large, chipped bone-shaped scythe behind him. His movements are slow and deliberately unhinged, occasionally twitching or stuttering in space, as if skipping frames.
☠️ Skull & Face
Skull is cracked, with one side heavily fractured and dripping a mixture of red dust and black void ichor.
His left eye socket is permanently weeping a thin stream of red, while the right glows intermittently with a twisting, spiral void glyph, suggesting Nightmare's influence.
Teeth are jagged and uneven now—some look broken or fused with bone dust.
The back of his skull has burn scars, etched in spiral runes where Nightmare touched him during possession.
🧥 Clothing
Hoodie: His classic blue hoodie is now shredded and elongated, stained with red, brown, and black void-blot patterns. The hood hangs loosely like a cowl, sometimes lifting on its own as if aware.
The sleeves are uneven: one torn off completely (revealing a sinewy, corrupted skeletal arm), while the other is stitched with timeline thread, glowing dimly in shifting colors.
Shorts are more tattered, partially replaced with black leather armor patches, seemingly merged with his bones.
Wears a belt of soul fragments—small, cracked pieces of colored soul shards float around his waist in orbit, murmuring in pain.
✋ Hands & Weapon
Left hand is skeletal and covered in black-glitched dust. It constantly trembles, as if still resisting control.
Right hand clutches a massive corrupted scythe, bone-themed, forged from his own summoned bones. The blade leaks a black-violet mist that erases light instead of reflecting it.
Occasionally, a spectral image of a red-stained knife flickers into his hand from memory—he always drops it instantly.
👻 Nightmare Features
Dust particles around him are now alive, whispering voices of the fallen. They swirl constantly, creating a cloud of choking emotion (regret, fear, anger).
His Gaster Blasters are fused with nightmare glyphs, looking like tortured skulls with melted sockets, beams shaped like jagged claws.
From behind, a twisted cloak of souls sometimes appears—shadowy silhouettes of those he killed, crying out or shielding him, depending on his mood.
Black bone spikes emerge from his back like wings at times, flickering in and out as the Nightmare strengthens.
🔊 Sound / Voice
Speaks in a raspy, broken whisper, with echoes of other Sanses behind his voice.
Sometimes he glitches mid-sentence, repeating words like "sorry… sorry… sorry…" before continuing.
His footsteps sound like crunching dust and static, sometimes causing the environment to briefly "rewind" around him.
⚔️ Powers & Effects
Dust Shift: Teleports by breaking apart into dust and reforming elsewhere, leaving an echo of a scream behind.
Soul Anchor: Can forcibly bind enemy souls in place using fragments of those he killed—guilt as a weapon.
Timeline Split: Can fracture a moment into multiple false outcomes—attacks unpredictably from those alternate states.
Silent Judgement: Emits a pulse of regret-fueled magic that silences the area—no sounds, no colors, no choices.
🎨 Color Palette
Bone/Skin: Pale gray-white with tinges of brown-red and black veining.
Clothing: Torn navy blue, washed-out greys, corrupted blacks, with blood-like reds.
Eyes/Soul: Right socket glows void purple with glyphs, left weeps bright red dust.
Aura: A mix of black static and drifting red particles, forming a ring of corrupted soul residue.
──────────────🕸️ NM!Betty[1]: "The Broken Star of Nightmare"
🌌 Core Theme
NM!Betty is the corrupted echo of a once‑joyful heroine, warped by the drone's red conversion beam into a living conduit of fear. She is Nightmare in bloom—both beautiful and grotesque, a study in how innocence fractures under pure malice.
👁️ Overall Aesthetic
Silhouette: Tall and lithe, with elongated limbs that give her an almost marionette‑like grace. Her edges flicker, as if she's phasing between reality and a static‑ridden transmission.
Posture: Slightly forward‑leaning, poised perpetually at the moment before a strike. Her weight seems to float, making her movements eerily silent and unpredictable.
🧠 Head & Face
Eyes:
Left: Glows with a searing fuchsia iris and narrow black slit—piercing and accusatory.
Right: A pure void, a swirling black orb that absorbs light and seems to whisper madness.
Mouth: Stretched into an unnerving grin; thin lips crack open in jagged lines, revealing teeth that glint like shards of nightmare glass.
Hair: Once soft and blonde, now inky black tendrils crowned with pulsating pink veins. Each strand writhes of its own accord, reacting to her emotions.
🧥 Attire
Hoodie: A shredded, charcoal‑gray jacket lined with glowing pink fissures. The hood drapes over her face, casting half of her features in shadow.
Scarf: Transformed into a living, shadow‑tendriled wrap that coils around her neck and shoulders—capable of slashing or restraining on her command.
Skirt & Leggings: A ragged, layered skirt of torn fabric and shadow fluff. Beneath, dark leggings marred by luminous runes that pulse when she channels her nightmare power.
✋ Hands & Accessories
Fingers: Thin, claw‑tipped, each fingertip crackling with pink‑black energy like static.
Tatters & Glyphs: Floating fragments of broken star‑shaped shards orbit her wrists and waist—each inscribed with a sigil of despair gleaned from the drone's core data.
🩸 Nightmare Features
Corrupted Aura: A swirling haze of black and neon pink mist that distorts the air, tinging it with a faint, metallic scent.
Reality Breaks: Wherever she steps, the ground splinters, leaking veins of glowing pink corruption.
Echoes of the Drone: Occasionally, a red four‑pointed star pulses behind her eyes, betraying the drone's lingering influence.
🔊 Voice / Sound
Speaks in a soft, childlike lilt layered over a low, dissonant drone—as if two voices speak at once, one pleading, one condemning.
Her laughter is delayed, echoing seconds after she stops, dripping with static.
⚡ Powers & Effects
Nightmare Beam: Fires a concentrated pulse of red‑pink corruption that fractures souls rather than killing outright.
Phantom Grasp: Conjures spectral tendrils from her scarf to snare and distort her foes' perceptions.
Fear Cascade: Emits a shockwave of psychic terror—enemies see their worst memories in flickering visions before being overwhelmed.
🎨 Color Palette
Skin: Pale magenta, webbed with dark veins of black mist.
Clothing: Charcoal gray, shot through with neon pink cracks.
Energy: Black‑pink static with flashes of crimson at climax.
─────── 🕷️ NM!Betty – Phase 2: "The Bloom of Hate"───────
🩸 Core Theme
In this phase, NM!Betty transcends her previous form, becoming a vessel entirely consumed by Nightmare energy. She embodies a fusion of her original self and the malevolent force of HATE, resulting in a being driven by pure destruction and devoid of empathy.
👁️ Overall Aesthetic
Silhouette: Her form becomes more fluid and less human, with limbs elongating unnaturally and her posture adopting a predatory hunch. Her movements are erratic, as if she's constantly glitching between dimensions.
Aura: A dense, swirling mist of black and deep magenta envelops her, distorting the space around her and causing the environment to waver as if under immense heat.
🧠 Head & Face
Eyes: Both eyes are now voids of swirling darkness with piercing pink irises that glow ominously. They emit a faint, constant trail of magenta energy.
Mouth: Her mouth stretches wider than before, filled with jagged, obsidian-like teeth. When she speaks, her voice echoes with multiple tones, some human, others monstrous.
Hair: Her hair flows wildly, composed of tendrils of shadow interlaced with strands of glowing pink energy. It moves as if alive, reacting to her emotions and intentions.
🧥 Attire
Clothing: Her previous garments are tattered and fused with her form, appearing as extensions of her body. The fabric seems to bleed into the shadows, making it difficult to discern where her clothing ends and her body begins.
Accessories: Chains of dark energy wrap around her arms and torso, pulsating with a rhythm akin to a heartbeat, symbolizing her bond with the Nightmare essence.
✋ Limbs & Appendages
Arms: Her arms can morph at will, transforming into blades, whips, or additional limbs. They are covered in shifting patterns that resemble ancient runes.
Legs: Her legs have elongated, and her feet have transformed into clawed appendages, allowing her to move swiftly and grip surfaces unnaturally.
🩸 Nightmare Features
Shadow Manipulation: She can extend her shadow to ensnare or attack foes, with the shadow acting independently to some extent.
Corruption Field: An area around her becomes tainted, causing the environment to decay and enemies to experience hallucinations or intense fear.
Soul Extraction: With a mere touch, she can extract fragments of a being's soul, using them to augment her power or create minions.
🔊 Voice / Sound
Voice: A haunting blend of her original voice layered with deeper, more guttural tones. It reverberates unnaturally, causing discomfort to those who hear it.
Ambient Sounds: A constant, low hum surrounds her, interspersed with whispers and distant screams, as if the voices of the consumed are trapped within her.
⚡ Abilities & Powers
Nightmare Infusion: She can imbue objects or beings with Nightmare energy, corrupting them to serve her will.
Reality Distortion: Her presence warps reality, causing time loops, spatial anomalies, and visual distortions in her vicinity.
Regeneration: Injuries heal almost instantaneously, with her form reconstituting from shadows and energy.
Energy Projection: She can unleash concentrated blasts of Nightmare energy, capable of obliterating matter and disrupting magical constructs.
🎨 Color Palette
Primary Colors: Deep blacks and purples dominate her form, accented by glowing pinks and magentas that highlight her corrupted features.
Energy Effects: Bright magenta and crimson hues accompany her attacks and abilities, leaving trails of light in their wake.
📜 Lore Summary
In this evolved state, NM!Betty has surrendered entirely to the Nightmare essence, her identity eroded by the overwhelming power she wields. She exists as a force of annihilation, her actions driven by an insatiable hunger to spread corruption and despair. This transformation marks the point of no return, where redemption is no longer possible, and only destruction remains.
──────────────────NM!Error – "The Fragmented Collapse"
General Appearance:
NM!Error stands tall, more chaotic than any of his counterparts — but in a way that feels deliberate, as if the Nightmare corruption bent to his code rather than overwriting it. His body is still largely skeletal, but completely blackened to the point of reflecting no light. Instead, his bones shimmer with subtle, shifting tones — a dark spectrum between deep violet, neon glitch-pink, corrupted red, and an unearthly turquoise that phases in and out like corrupted pixels.
Face & Eyes:
His once hollow sockets now overflow with a storm of static and code. From his left socket drips a constant stream of corrupted red glitch—liquid code—falling in jagged, broken lines down his cheek like a bleeding glitch. His right socket displays a flickering red pupil, glitching between standard Nightmare sigils and unreadable void symbols. Both eyes twitch erratically as if he sees multiple timelines layered on top of each other.
Occasionally, Error's face distorts—shifting into corrupted fragments before reforming again, like an unstable mask that can barely contain what's inside.
Clothing & Thread-Tendrils:
His hoodie is torn and darkened, stitched together by glowing crimson error code instead of thread. Hanging from his sleeves and shoulders are long, writhing strings—no longer just blue or glitchy, but solidified Nightmare tendrils encoded with error glyphs. They float and twitch in mid-air, extending unnaturally far from him, occasionally reaching out as if trying to grab and dismantle reality itself.
Torso & Limbs:
NM!Error's ribcage is cracked, glowing faintly with glitch-red circuitry beneath—like a corrupted soul reactor inside. His hands are jagged and larger than before, the fingers sharp like claws, constantly glitching in and out of phase. Any code he touches visibly corrupts—turning to dark pixels before shattering or warping unnaturally.
His legs are wrapped in barbed strings of Nightmare code, acting like animated restraints he willingly uses to anchor himself between timelines. When walking, he leaves behind trails of glitch-static and faintly red, warped footprints that burn into the air for a few moments before fading.
Aura & Voice:
He doesn't speak often, but when he does, his voice is multi-layered: one tone is his original distorted voice, the second is a whispering Nightmare snarl underneath, and the third is a broken echo of himself trying to resist. His laugh is broken, glitching between dread and sorrow.
His very presence warps code, creates silent static in sound, and makes environments degrade around him. Timelines near him begin to collapse, fragment, and loop without warning. He doesn't just destroy AUs anymore—he corrupts them into unrecognizable nightmares, endlessly looping and glitching until they collapse on themselves.
──────── ⚠️ NM!Error – Emotional Stages & States ────────
1. Null/Error
(The Void-Cold Core – "Stable NM!Error")
Appearance:
NM!Error in his most composed state is terrifying not for his rage, but for his calm. His form is precise—his black skeleton lined with pulsating crimson cracks, like code bleeding from inside. His hood cloaks most of his face in shadow, and the ERROR symbols on his sleeves glow steadily but dimly—no longer a glitch, but a brand burned into his essence.
His strings are still, taut, ready—like waiting tripwires across space.
Behavior:
This is the most "in control" NM!Error becomes. He's unnervingly quiet, contemplative, and tactically perfect. Every glitch and movement is deliberate. He's detached, cold, and analytical—weaponizing his Nightmare-infused logic like a scalpel instead of a hammer.
Interactions:
Speaks in fragmented sentences, as if choosing every word to avoid awakening the storm inside. This is NM!Error when he's stalking, scheming, and calculating—more of a phantom virus than a brute force. If he's here, something already went wrong.
2. Fractured/Error
(Agitation State – "Crack in the Code")
Appearance:
His body flickers with harsher static. Glitchy red symbols appear rapidly across his bones and robes like corrupted command prompts. His pupils fracture into red shards, sometimes cycling symbols or unreadable void language. The Nightmare essence writhes under his skin like veins about to burst.
His strings begin to animate wildly—moving like spiders' legs twitching without order.
Behavior:
Here, NM!Error is tense, pacing, growling lowly. He's irritable, quick to react, and reactive instead of proactive. The Nightmare corruption starts to "speak louder," influencing more of his subconscious. His behavior becomes glitch-spiked—short loops in speech, repeating phrases, unfinished thoughts.
Interactions:
Threatens before acting, but his warnings carry weight. He'll snap at allies, bark orders, and may destroy small portions of environments just to silence the voices. It's a sign he's on the edge—not enraged, but unraveling.
3. Apex/Error
(Rage Manifest – "Glitch Tyrant")
Appearance:
Unstable. Horrific. His entire body is sheathed in glitch-spikes and crimson flame-glitches—erratic red lightning sparking from his limbs. His hood is down now, revealing his entire skull—half fractured, half corrupted by twisting sigils of the Nightmare code etched across his cranium.
His mouth distorts when he speaks, his words glitching into static mid-sentence. The strings become whips—unstable and flailing with screaming glitch echoes.
Behavior:
Pure wrath. NM!Error becomes nearly uncontrollable—an entity lashing out at reality itself. Timelines he walks into begin fragmenting just from his unstable aura. His strings stab space, trying to tether collapsing AUs just to shatter them himself.
Interactions:
Furious and unpredictable. In this form, he argues with himself, sometimes pausing in battle to scream at something only he hears. Nightmare's influence has overclocked his emotions and drive—everything feels like betrayal. Even allies are risks.
4. Broken/Error
(Collapse State – "Self-Corruption")
Appearance:
His form becomes inconsistent—entire body parts flicker between existence and raw code. Red and black error boxes replace chunks of his legs and arms. His symbols distort, looking like half-loaded files or corrupt data dumps. Glitch ash falls off him constantly.
His eye sockets leak dark glitch tears instead of code, and parts of his strings unravel and dissolve midair.
Behavior:
A rare, defeated state where NM!Error is overwhelmed—not just by Nightmare's corruption, but by himself. He's not acting. He's breaking down. He might mutter strings of corrupted thoughts, sometimes echoing his old, pre-corruption goals in confusion.
Interactions:
Withdrawn. Crouched. Vulnerable—but not safe. If approached incorrectly, he can react violently or vanish. It's a moment of silent internal screaming. He's still aware—just crushed by the weight of it all.
5. Prime/Error
(Focused State – "The Architect of Collapse")
Appearance:
Glorious in horror. A perfected combination of Error's strategic brilliance and Nightmare's precision. His body is armored in encoded black plating, trimmed in glitching blood-red. The strings have fused into controlled tendrils—fewer, but sharper, shaped like daggers made of code.
His ERROR symbol becomes a crown on his hood—burned into the fabric, always visible, always watching.
Behavior:
This is NM!Error when he's in full command. He no longer reacts. He dictates. Calm, firm, and tactically unstoppable. Timelines fall in front of him like programmed dominoes.
Interactions:
If he speaks to you in this state, you've already lost. Every movement is backed by complete intention. He believes he is the end.
6. Hollow/Error
(Suppressed State – "What's Left of Me?")
Appearance:
A silhouette—barely formed. Just lines of static and a soft red glow beneath a cloak of void-light. No symbols. No strings. Just the ghost of what once was Error… and now what might never return.
Only his eyes remain—dim twin red dots, slowly fading between awareness and nothingness.
Behavior:
Trapped between NM's control and his own lost soul, Hollow/Error is a whisper, a memory. Not broken—drained. Emotionless not from coldness, but because the emotion was burned out of him. Every action feels like an echo.
Interactions:
He doesn't resist. He doesn't speak. He just… watches. You don't know if he'll attack, disappear, or collapse. This version may never fully recover… or he's only waiting.
───────────────── ⛓️ NM!Fatal Error – The Collapse Manifest
Name: NM!Fatal Error
Alias(es): Collapse Code, The Glitch Devourer, Red Static, the Malfunction of All Things
Overview:
NM!Fatal Error is the embodiment of catastrophic instability—a walking collapse of digital existence. Unlike NM!Error, who retains some structure in his descent into NM corruption, NM!Fatal Error is a terminal failure made manifest. He has no stability, no center, no filter. His form is constantly shattering, rebuilding, and tearing itself apart again—not from damage, but as a natural state of existence.
He is a weapon with no safety lock, a virus whose logic core was obliterated by the influence of NM. What little still holds him together—his lingering bond to his Papyrus—does not tame him, but amplifies his aggression into devastating, emotion-fueled surges of destruction.
⚙️ Visual Design:
🧩 General Shape:
NM!Fatal Error retains the general body silhouette of Fatal Error, but it's constantly breaking down and glitching. His form never settles—chunks of him constantly phase in and out, like corrupted render layers or invisible geometry failing to load.
His left arm may appear to be made entirely of tangled red glitch tendrils, violently twitching and growing before retracting and glitching again.
🖤 Skeleton & Body:
The bones of his skeleton have turned charred black, but not like normal NM-black—it's inverted static black, like a living silhouette with broken scanlines.
Pieces of his ribs or limbs sometimes snap out of alignment, floating beside him briefly before glitching back into place.
Unlike NM!Error's more digital corruption, NM!Fatal Error's body looks like it's being torn from a different reality frame altogether.
❌ Glitches and Code:
The classic "FATAL ERROR" text now appears twisted, randomized, reversed, and often replaced with flashing red system-critical errors like:
[SYS_FATAL_HEARTEXCEPTION]
[000000.REDLINE.COLLAPSE]
[GL!TCH//##//UNKN0WN]
His body emits raw glitch code like smoke—chunks of broken sprite textures, 3D polygons, and even corrupted file icons pulse around him in orbit, fading in and out like warning messages from a deleted system.
🔴 Eyes and Expression:
He has no visible pupils or sockets anymore. Instead, there's a spiral void of glitch and red code static, like a collapsing singularity.
When he's enraged (which is almost constant), the spirals unravel, revealing deep vortexes of red, pulsing like a dying hard drive's LED light.
🔥 NM Effects:
He emits the NM signature red-black flame, but in NM!Fatal Error, it's not flame-shaped—instead, it's like a corrupted bloom of code particles, exploding outwards like anti-light, leaving traces of deletion wherever they touch.
He has NM "veins", but they're less like veins and more like threaded red wires through his glitch mass, snaking unnaturally across his body.
🧠 Personality & Behavior:
Mindset:
Non-verbal. Rarely speaks, and when he does, it's a glitch storm of indecipherable error messages and garbled screams. The sound feels like a virus trying to load in your ears.
He doesn't think—he executes. His existence is a command line constantly firing off unchecked instructions, and his body is trying to obey all of them at once.
Purpose:
He's a force of pure elimination—a program looped on endless destruction, especially when triggered emotionally by anything tied to his memories of Papyrus.
Unlike Error, who might destroy AUs methodically, NM!Fatal Error annihilates the concept of them. He destabilizes the foundation, causing AUs to collapse from inside their code structure.
Unique Traits:
Glitch Shell: At any time, NM!Fatal Error can shed his outer form in a burst of glitch static, leaving behind a decoy glitch husk while his true self phases elsewhere. It's instantaneous and untrackable.
Memory Fractures: If someone mentions his Papyrus, there's a visible shift—a moment of raw, red surge, as if his corrupted heart is remembering something that fuels him with agonizing purpose.
Drone Remnants: The drone from NM!Gaster embedded into him left shrapnel-like fragments in his code. Sometimes they twist outward like blades or fire corrupted red rays without warning.
💬 Summary:
NM!Fatal Error is less of a character and more of a glitch apocalypse given shape. He exists in a permanent crash state, an error loop that never recovers. Compared to NM!Error, who might lose himself slowly, NM!Fatal Error never had the option—he's already gone. What's left is a virus with a broken heart, running on rage and ruin.
[1] Nightmare Mode Bête Noire, or for short "NM!Betty".
I'm not french, so I needed to research.