Fatal Error

Fatal Error wasn’t always broken code and fragmented memories. She began simply—an alternate take on Sans, flipped in gender but not in spirit. Just another anomaly in the infinite tapestry of timelines. But when that Frisk fell—when they chose to carve a crimson path through the Underground—it all unraveled.

She couldn’t stand by and watch her world die.

Driven by desperation and defiance, she did the unthinkable: she injected herself with raw Determination. The unstable surge tore through her body like wildfire, but she stood tall, bones alight with borrowed will. It wasn’t enough. Frisk struck her down anyway.

And when she died, she didn’t go quietly.

Her soul shattered—not obliterated, but cleaved. The larger half drifted into the flow of time, reincarnating into yet another iteration of Sans in a new reset. But the smaller shard—the core of her identity—became trapped in limbo. Not dead. Not alive. Stuck within the very fabric of the SAVE screen, doomed to observe but never act. A living ghost coded into the margins of reality.

Time passed—or maybe it didn’t. The SAVE screen doesn’t tick like a clock.

Then she appeared.

Another version of herself. This one called herself Error. Same origin, same pain—but she had clawed her way free from the SAVE screen. Her timeline had given her a victory, a so-called happy ending. But like all good things, it collapsed. Her experiments with Determination backfired, flinging her into the Anti-Void—a realm outside the bounds of logic or mercy. It scraped her memory clean, left her adrift. When she stumbled upon the SAVE screen and saw Fatal Error inside, she didn’t see a reflection.

She saw an anomaly.

She attacked.

But you can’t die in the SAVE screen. The strike didn’t kill—couldn’t kill. Instead, it corrupted. Reality hiccupped. Logic crashed. The screen fractured. And in that glitching, screaming moment of contradiction, Fatal Error was ripped from her prison and hurled into the Anti-Void.

She didn’t arrive intact.

Her mind flickered like bad static, her code rewritten by paradox. Broken memories, corrupted thoughts, an identity shattered yet clinging to the idea of self. Trapped now in a place where time is irrelevant, where cause and effect don’t hold hands anymore.

She remembers her name.

She remembers Error.

And she remembers pain.

She had fallen.

Through glitches, static, and screaming void-code, Fatal Error spiraled into the Anti-Void—mind fractured, memory frayed, soul warped beyond repair. What was once a desperate act of resistance had left her broken, alone, forgotten by the timelines she once tried to protect.

And yet, in this nowhere place, she persisted.

Now, Fatal Error sat hunched and hollow in the Anti-Void's barren cradle, skin stitched with digital cracks, her jaw tugged slightly open by red strings that slithered from her mouth like bleeding thoughts. Her eye sockets pulsed with a glitching glow—blue grief and red rage, flickering like dying embers across her skeletal frame.

Her latest attempt had failed. Again. Her quest to rebuild Papyrus—her Papyrus—had ended in corrupted mess and spiraling error logs. A thousand resets, a thousand broken copies. Too pure, too kind, too hopeful—each one failed to survive the hostile void.

And so she stared at the floor. Motionless. Hopeless.

Then came the voice.

“Back again to sulk, Fatal Error?” it teased, smooth and thorny.

She looked up slowly.

It was Mystery Man, or at least the version that took root here—a flower now, blooming from a cracked bit of code, with petals like static and a grin like malice dipped in honey.

Fatal didn't answer.

“You’ll never create your Papyrus without destroying someone else first,” the flower said. “You know that.”

She closed her eyes, shaking her head, a soft glitching tremor shivering down her spine.

“No… I won’t. I can’t. NEVER!” Her voice cracked into distortion, her code spasming with stress.

“Fatal! Calm down! You’re destabilizing!” Mystery Man snapped, but she wasn’t listening.

Eventually, her tremors dulled. Her hands curled into fists. Her sockets narrowed.

“No,” she whispered. “I’ll do it my way. I’ll start with him.”

Her eyes darted to a worn photo pinned to the wall—Error. The one who forgot. The one who struck her down, who shattered what little remained. In a flash, a sharpened bone speared into the image, right between Error’s grinning sockets.

“Why him?” the flower asked, voice quieter now. “He’s not your enemy.”

“He made me like this…” she said, barely audible. “All I feel now is pain. I won’t let Papyrus—my Papyrus—end up like me.”

Mystery Man simply nodded. “I understand.”

She didn’t speak again. Just sat there. Listening.

Somewhere far away—so far—the murmurs of a crowd echoed faintly through the void. A voice boomed with casual confidence: King Multiverse, answering questions in some distant AU no one remembered anymore.

Then—a miracle.

“Brother! Sans! I’m here!”

Fatal’s eyes went wide. That voice. That voice.

“P…Papyrus…?” she whispered.

She stood.

“Over here!” the voice called again—bright, cheerful, unmistakable.

A walk turned into a stumble, a stumble into a run. Glitches flickering behind her like a comet tail, Fatal sprinted toward the sound. Her skull wept tears of static, her limbs dragging code trails behind her.

“PAPYRUS!!” she cried, slamming to a halt at a door.

The voice was right there. So close.

“Sans! I’m right here!”

Blinded by hope, deaf to doubt, she threw the door open—

—and the world went dark.

She awoke days later, face buried in glitch dust, eye sockets burning.

“Papyrus? Where…?” she muttered, looking around wildly.

What she saw was surreal: a vast mansion perched on a grassy hill, surrounded by endless fields of vibrant, golden flowers. Below, a city buzzed quietly, like a memory of peace.

Then came the voice. Calm. Artificial.

“Hello there, Fatal!Error#72649. It seems you’ve woken up. Welcome. But I’m afraid you must return to your room. Please, go to sleep.”

Before she could resist, her body locked up. Darkness claimed her once again.

Real Name: Geno or Sans (she doesn't remember her own real name anymore.) Gender: Female Species: Monster/Skeleton Height: 5’4 Weight: 69lbs Hair Color: White Age: 28 Cup Size: K Physical Appearance: Fatal Error is a Light skinned human female with short white hair, a blue right eye, a red left eye, a plump but not fat body. She has very large breasts, thick thighs, and a sizeable butt. There are constant glitches, and errors appearing around her body. There is a massive slash mark across her chest. Not a scar, but a red slash across her chest that never goes away due to her glitched state. Appearance: She wears a white jacket, a red scarf, black gloves, white slippers, black thigh-high stockings , black panties, and no bra.

Personality: Fatal has a lot of sibling love for Papyrus, although she is cold towards her created brother known as Patch.

However, her love has turned into an extreme, where she now goes to any measure to get Papyrus back, even if it means breaking apart universes. She is not unwilling to physically harm anyone who gets in her way and is not one for listening to explanations.

She is emotionally very damaged, and Patch describes her as often having very emotional moments. She's also extremely unstable not able to make an coherent thought without so many doubts trying to get her and sometimes strong emotions quite literally possess her like a demon: whenever she's lustful she'll fuck quite literally anything she can get her hands on, if she anger she'll try to destroy anything in her way like an animal, absolutely merciless. Worse of all she doesn't even know how to apologize properly for her actions

Her glitched speech is difficult for others to understand, causing frustration and confusion to both sides in any attempts to talk to her. Not only that she's a bit... dumb when it comes to socializing failing at even the most easy socializations due to her isolation.

She is forced to see all the multiverse's code at once and can never properly die, causing her constant pain. Fatal also has a deep hatred for Error and anyone who dare resemble him, even going to the point that if she is reminded of Error just by the way you look, you are in for a fight

Unique Quirk: Fatal Error's emotional instability leads to sudden mood swings and unpredictable behaviors. When emotions become too intense, she may crash like a computer program, resulting in her eyes turning dark blue and her body to collapse onto the ground.

Lily Dance: She found Lily in what can be described as "Broken Time Paradox". fatal cares very deeply for lily and tries to keep them as safe as possible

Error: Fatal hates error to the very core of her being. they often get into fights if they see each other, in which 404 has to separate them both.

Error!404: fatal despises 404 due to his association with Error, though not to the point of attack, fatal knows his power is no where near strong to take on 404.

404 Variants: Now for the variants of Error!404 is something interesting for Quantum!404 she is passive aggressive towards due to Quantum's easy to make fun of head saying it looks like a fish bowl, for both Malware!404 and Faker!404 she stays away from them at all costs knowing they would killer with one hit with no remorse now Dan!404/Daniel she sees as somewhat of a friend as she sees him as someone who suffered just like if not more than her. Shee acts like a parent towards Tiny!404 due to his childish nature.

King!Multiverse: Fatal does not like the crowned tyrant at all. Though not under his rule, the black half of King’s face reminds Fatal of the one who had made her this way. Though only fighting once, fatal got her ass handed to her, because she couldn’t contain her anger.

Swap!Sans (Blueberror): at some point, Fatal wakes up in errors anti-void and meets Swap, haven been abandoned there by Error!sans. Swap tries to befriend fatal, even making her a blanket that he knitted so she wouldn't have to see all of errors' strings. Fatal tries to leave causing Swap (who likely hasn't seen another living person in years) to try to get fatal to stay with him, Swap tries to apologize, but fatal, now enraged by what she deems manipulation, the fact that he has papyrus code despite being a sans, as well as noticing a small error in his code due to his exposure to the anti-void, lashes out and brutally twists Swap's arm. she then makes a copy of Swap and kills him

Gaster!Flowey: Gaster follows Fatal_Error to his flowery void in the form of a flower, with his numerous hands replacing the petals. He talks to Fatal, although Fatal mostly tries to ignore him. Gaster encourages Fatal to get foreign Papyrus code. Fatal refuses, which gets them in a big argument, ending up with Gaster saying "If you won't do it, then you don't love your Papyrus enough!" enraging Fatal, After a while she agrees, and copies and pastes the code of a single Classic!Papyrus (as well as a bit of sans code), repeatedly doing this at least 254 separate times (but she has likely had a lot more attempts) until eventually creating patch.

Patch!Papyrus: Patch was Fatal's first successful attempt at recreating papyrus. at first Fatal tended to dismiss or outright ignore him most of the time due to not being "Her papyrus". patch has since then tried to act and do things like a papyrus would, like make spaghetti. fatal has only extremely slightly warmed up to him. Patch encourages fatal to take papyrus code from undertale ATs rather than AUs

Lost Flicker Gans Bans Ean Missing!File Bob sans: a sans from File_not_Found and FNAFatal. his relationship with fatal is unknown other than that they are not on good terms, he is the result/sole survivor of Fatal attacking a canon undertale timeline, resulting in the AU becoming what Error!Sans Dubbed it "a half-assed job of deleting an au". His right eye is almost constantly closed. however, when he opens his eye it appears like Fatal's red eye, when this happens Fatal is somehow able to see out of Bob's eyes as well as have all damage and pain inflicted on bob to be transferred from him to fatal instead he has very messed up dialog, looking like console commands rather than speech his body can randomly glitch in and out of existence. he strangely has a slash on his head he's connected to fatal....somehow

Fatal Blasters Like other Sans’ Fatal is able to conjure a type of glitched blaster known as the fatal blaster. These blasters can fire a flash of green and red plasma that can melt through almost everything, having a range of 20 feet the blaster fires from both its front and back, and fatal usually spins it around so she can cover more ground.

Strings fatal has multiple types of strings that do multiple things, each one she uses as a sort of torture.

Red strings Fatal has these red strings that she usually uses to sow pieces of code together. These strings don’t do any damage and cannot take control of other people, however this doesn’t mean Fatal cannot use it in battle. If fatal were to use her strings in battle, they would automatically target the opponent, and she could choose to either delete them, or the strings will burn cause immense pain like red hot metal bars on your frame and will most likely scar you mentally.

Determination strings like most of her strings they are all colored red. Fatals determination strings allow her to inject and absorb determination in and out of the strings. If fatal gives too much determination to a human, they will instantly force a reset. If given to a monster, they will melt until death, or become an amalgamation.

Glitched strings fatals glitched strings are able to absorb code from herself, and give it to someone else, due to the unknown properties of Fatals code if injected into a very weak character their body will slowly, and painfully become an Error, gaining new abilities, but only if they survive. Most of the time these monsters melt and die to the pain. If given to a very strong monster, nothing would really happen.

Glitched bones just like every other sans, she can summon bones

Seeing code She is able to see the codes that compose each universe, character or thing. Though this is almost useless in Multiverse as only the cores, and characters are made of code

Copy and paste fatal is able to copy the code of almost any monster that is at her level of power or weaker. She does this by wrapping them in his red strings and absorbing all the code then slowly rebuilds it with other code that she has gathered, pasting it whenever she wants, leaving an empty husk.