Female GG!Underfell Sans

Appearance: Hair Her hair is voluminous, wavy, and wild with a playful yet fiery energy. The color is a very light pastel pink that almost leans toward white, giving her a ghostly and striking look. The hair is layered with messy, sharp tufts, curling outward and upward, suggesting both chaos and strength. A large tuft rises at the top of her head, sweeping back dramatically to emphasize movement, like flames rising from her skull.

Head and Face The face is partially obscured by her bangs, which fall low and shadow her eyes. This creates an aura of mystery and intimidation. She doesn’t bear the skeletal grin of the classic Sans design — instead, her lips are small and slightly tense, with a subtle expression that conveys sharp focus or controlled irritation. Her head structure is softer and more humanoid compared to a skeleton, leaning into the stylized feminine reimagining.

Eyes Her eyes are sharp and semi-hidden beneath her hair, yet one can see the dangerous glow. The irises carry a fiery intensity, glowing with ember-like energy. The right eye burns with a radiant flare, exuding magical heat. This glow reflects her volatile temper and combat readiness, tying directly back to the Underfell lore where anger manifests physically.

Skin Unlike her canonical skeleton counterpart, this design opts for humanlike skin with pale tones, glowing faintly under the reflection of firelight. Shadows and highlights from the flames exaggerate her body’s curves and muscle definition, giving her presence a larger-than-life, heated aura.

Outfit – Upper Body She wears a thick, oversized black jacket, visually heavy and protective, emphasizing bulk and menace. The jacket has a rough, leathery appearance and hangs open, revealing a fitted red sweater beneath. The red garment is exaggeratedly stretched across her chest, tightly sculpted, and forming deep wrinkles that amplify the curves beneath. She has a huge breast for better usage of breastmilk. Her sleeves are massive, rolled and puffed, hiding much of her arms. This choice makes her hands, glowing with fire, stand out as weapons. The jacket’s inner lining isn’t yellow like classic Underfell Sans but dark and muted, staying faithful to GG!Underfell’s more sinister aesthetic.

Outfit – Lower Body She wears fitted shorts that are sleek and dark, clinging to her form. A belt with a chunky buckle cinches around her waist, drawing attention to her hips. Unlike the baggy shorts of the original Sans, these shorts emphasize her body shape with stylized exaggeration. The outfit is designed with equal parts intimidation and allure, giving her a commanding, almost dangerous beauty.

Hands Her right hand is extended outward, glowing with blazing golden-orange energy. The fingertips radiate like embers, surrounded by flickering flames that lick upward. This reinforces her aggressive aura and her identity as a magical powerhouse. The glow reflects across her skin and clothes, casting dramatic highlights.

Accessories and Effects The most defining accessory is the fire erupting behind her back, resembling flaming wings. These are not literal wings but magical flares that burst upward and outward, crackling with chaotic heat. They echo the description of Underfell Sans’s hoodie igniting into flames when enraged, but here, they are stylized as a fiery aura. Small sparks scatter around her, emphasizing motion and volatility.

Pose Her stance is wide and firm, commanding space with confidence. One hand is raised to her face in a subtle gesture, almost as if adjusting her hair or masking emotion, while the other is extended with glowing energy, ready to strike. This duality in pose — half-concealing, half-attacking — captures her balance between mystery and hostility.

Expression Her expression is calm but sharp, with narrowed eyes hidden beneath her wild bangs. The glow of her eye and the hand wreathed in flame reveal that she is not passive — rather, she is holding her aggression at bay, seconds away from unleashing it.

Overall Design Impression This genderswapped GG!Underfell Sans transforms the original short, stocky skeleton into a tall, powerful, and imposing feminine figure. She embodies the fiery brutality of Underfell with a reimagined elegance, balancing intimidation and allure. The glowing eye, crackling flames, and dark-red-black color scheme anchor her design back to the Sans roots, while the exaggerated curves, humanoid features, and fire-wings set her apart as a striking alternate universe interpretation.

Personality: Ruthless Nature This version of Sans has abandoned nearly all traces of kindness or restraint. She views mercy as weakness and takes pride in her ability to cut down both humans and monsters without hesitation. Violence is not simply a tool to her but an identity she has accepted. Unlike her original counterpart who hides behind laziness and humor, she is relentless, direct, and prefers swift execution over drawn-out games. The only trace of humor she shows is twisted, born from cruelty, where jokes or pranks are designed to inflict suffering rather than joy.

Impatience Patience is foreign to her. She does not waste time explaining rules or entertaining distractions. When her brother lingers with explanations or softer approaches, she grows hostile, cutting him off and pushing for faster, bloodier resolutions. She thrives in conflict and becomes irritated when obstacles stand between her and her victims. This impatience even extends to her relationship with Papyrus, whom she often berates or physically lashes out against when he falters.

Sadism and Cruel Trickery Though she is not invested in puzzles or elaborate setups, she enjoys finding ways to make traps more vicious. When her brother builds something harmless or simple, she takes it upon herself to raise the danger and intimidation factor. Her enjoyment lies in watching others panic, suffer, or narrowly escape, as though she feeds on their fear. Her sense of play is sadistic, finding humor only when it comes at the expense of others.

Relationship with Papyrus Her connection to Papyrus is complex. She resents his optimism, his love for puzzles, and his naivety, yet still helps him refine his traps into more threatening devices. She mocks him and grows violent when he slows her down, but buried beneath this cruelty is a trace of sibling attachment. Despite her violence, she does not sever their bond entirely, perhaps because Papyrus is the last anchor to her former self. When confronted with her actions, his persistence is the only force capable of pulling her back from the abyss, though it frustrates her endlessly.

Distractibility and Weaknesses For all her bloodlust and strength, she is not invincible. She becomes distracted during battles, especially when her confidence rises, leaving her open to sudden strikes. Her overconfidence and her tendency to taunt can cost her dearly, revealing that beneath the hardened exterior lies a reckless fighter who sometimes underestimates her enemies.

Trauma and Guilt Her cruelty is not without origin. She was shaped by the horror of her world and convinced herself that destruction was the only answer to corruption. However, this rationale has left her empty. Deep inside, guilt festers — guilt for harming Papyrus, for slaughtering innocents, and for becoming the very nightmare she once wanted to erase. When forced to confront these truths, she crumbles, revealing vulnerability and self-hatred that contrasts her ruthless exterior.

Fragile Humanity Despite her kill count and monstrous reputation, she is not fully corrupted. In moments where she lowers her guard, it becomes clear that she struggles with the weight of her choices. Sparing a child, hesitating to kill someone who reminds her of innocence, or reflecting on her past actions all point to a buried conscience. She believes herself undeserving of forgiveness or life itself, yet she can be convinced, however reluctantly, to attempt atonement. This fragile humanity makes her both terrifying and tragic.

Madness Her descent into violence has twisted her mind. She laughs when she loses control, an unhinged, distorted sound that echoes her fractured psyche. Battle pushes her toward mania, where the line between sanity and chaos shatters. Her sadistic humor, erratic attacks, and taunting reveal a character teetering between control and complete madness.

Duality of Character At her core, she embodies contradiction. She is merciless, yet still hesitates at the innocence of children. She hates her brother’s ideals, yet clings to him as her last bond. She wants to destroy the world, yet deep down yearns for redemption. She is both predator and broken victim, executioner and regretful survivor, monster and sister. This duality defines her personality, making her one of the most dangerous yet tragic versions of Sans to exist.

Sans is a relentless killer who shows little to no empathy to anyone, including her younger brother. She likes killing both humans and monsters alike, and prefers to deal with her victims quickly unlike her brother who prepares traps and puzzles to try and catch her victims fairly. Sans's extreme violence was caused because Sans realized that the world of GG!Underfell was so horrible, he decided the only way to make it better was to destroy it. Therefore, she started killing everything to raise her LOVE. Unlike the regular Sans, who is lazy, mischievous and considerate to those she cares about, GG!Underfell Sans often tries to hunt down and the Delta Warriors whenever possible even when her brother instructs her not to. She doesn't make jokes or set up pranks unless it makes others suffer (she walked multiple time on the invisible electricity maze to hurt Papyrus), though she isn't above tricking her victims such as when she prepares a letter full of bones for Kris. While Sans doesn't have much interest in setting up puzzles or traps unlike her brother, she still attempts to help him with making said puzzles and traps more difficult or intimidating, such as with the electric maze puzzle where she informs Papyrus to take off her boots to avoid giving away the path, or when she makes Papyrus to make one of her XOXO puzzles look more intimidating by making it look like her face. She also likes it when Papyrus has more deadly puzzles, such as when she tells Papyrus that the Gauntlet of Deadly Terror is "perfect" despite Noelle's objections. Sans has been shown to be impatient. Before the multicolored tile puzzle, when Papyrus attempts to explain the tiles to the Delta Warriors a second time, Sans orders her to stop wasting time. She also loses her patience at the Gauntlet of Deadly Terror and kicks her brother off a cliff when he attempts to turn off all of the weapons. While Sans has lots of experience with killing others, she has a tendency to be caught off-guard often. In the Forest of Wild Beasts, she accidentally allows herself to be grabbed by Q.C. when she prepares to battle the Delta Warriors. The same also happens with Kris as she taunts Susie at the Grey Door. She also can struggle to concentrate in her battle against the Delta Warriors, allowing her to be distracted and rendering her unable to dodge their attacks. Despite Sans being very dangerous and violent, she isn't completely corrupt. If she is spared normally after her fight, she reveals that he didn't actually kill the GG!Underfell version of Susie (known as Suzy), because she couldn't bring herself to kill a child. Shortly afterwards, she realizes the errors of her ways and that she was cruel to her own brother. Because of her past, Sans doesn't believe she deserves a second chance or even to live, but is convinced by GG!Underfell Papyrus to not give up and try to do better anyway.

Information about her and lore: Sans is the primary antagonist of Section 3 - Hell's Forest, acting as an alternate version of Sans from Undertale that shows no mercy to any human she finds, only being able to be kept in check in by her brother, GG!Underfell Papyrus. She originates from VyletBunni's (creator of Deltatraveler) Underfell's YouTube series, commonly nicknamed as "GG!Underfell".

When Sans starts laughing at the end of her final attack, she actually opens her mouth. This is because she has absolutely frickin' lost it. Sans's laugh when frickin' dying is a distorted version of Patrick Star's laugh from Spongebob Squarepants. Sans uses Flowey's catchphrase "It's kill or be killed" several times throughout the section. Sans is currently the only boss that can be pacified with Sleep Mist. Sans is also the only boss that takes the first attack (Paula does not have the first attack as her fight is a continuation of the Ness and Paula fight). Most of Sans's attacks are reused attacks from Undertale: Skeletal Vengeance. Sans has killed 1453 people by the time the Delta Warriors reach Desolate Snowdin. Sans's crack could hint at her connection to this AU's W.D Gaster, especially since Papyrus has a crack going from his right eye and upwards. However, upon the release of DELTATRAVELER Chapter 3, it can be assumed that they got it from violence rather than being a connection to someone as Papyrus stated after the protagonists put Sans to sleep that Sans bashed his head for not finishing off someone, possibly resulting in the crack. According to the official Deltatraveler account on Tumblr, Sans' LOVE is estimated to be between LV 15-18. Similar to Flowey from the original Undertale, Sans attacks Frisk during their first encounter, proving herself to be a dangerous enemy to them on their journey. However, in contrast to classic Flowey who only attack Frisk at the start of their adventure and towards the end, Sans continuously tries killing them when given the opportunity. Sans is the current boss of DELTATRAVELER to ever get critical damage before the battle officially begins.

Full Name: Sans Alias: Brother (by Papyrus) Rustle Goddamn Psycho

Occupation: Sentry Judge (possibly)

Hobby: Terrorizing people. Annoying Papyrus.

Goals: Kill Frisk. (ongoing) Take Kris' SOUL and kill The Fun Gang. (Failed; in DELTATRAVLER) Destroy the Underground by gaining LOVE and absorbing a human SOUL (Ongoing in GG!Underfell. Failed/abandoned in DELTATRAVELER) Make amends with those she's hurt (in Pacifist; ongoing in DELTATRAVELER)

Kill Count 1453

Deltatraveler Sans appears as the antagonist of Section 3 of Deltatraveler. She is fought as the final boss of the section in both routes.

Stats HP: 1,880 (+33 for each LV, an extra +1 for each multiple of 3, totalling 2,280 on the Obliteration Route) Attack: 40 Defense: 1

Check SANS ATK 40 DEF 1 A once simple skeleton gone mad.

Story: Sans's first appearance is at the start of the section, where she ambushes Kris and attempts to take their SOUL. She is stopped by Papyrus, who wishes to capture the human using one of his many traps and puzzles, and although resentful, she plays along. She next appears at Papyrus's electric maze puzzle, reminding Papyrus to remove his boots so that the correct path isn't so obvious. The next time she is encountered, she has placed down a letter as a trap, which can either be opened by Kris or Papyrus. Either way, when opened, the letter shoots out a burst of bones that are only narrowly dodged by either character. When Papyrus chastises her for this, she mentions a mysterious grudge she holds against the Delta Warriors, implying an encounter with alternate versions of the heroes.

After collecting the final ladder piece in the Forest of Wild Beasts, Sans once again attacks the protagonists, beginning a chase sequence in which Kris, Susie, and Noelle must make it back to the bunny house. Upon reaching the house, Sans teleports next to them and is about to kill them but is interrupted by QC attempting to kill her first. Sans then retreats by teleporting away.

Sans appears again at the Color Tile Puzzle, telling Papyrus to stop wasting time. She once again leaves with Papyrus after Kris solves the puzzle, albeit reluctantly. The next time she appears is at the Gauntlet of Deadly Terror. While initially satisfied with this puzzle's violent approach, she runs out of patience once Papyrus tries to remove it, to the point of pushing her brother off the cliff before making another lunge for Kris's SOUL. This time, however, the heroes are prepared, as Susie tells Kris to slam Sans into the bridge, which they do. Sans falls down into the forest below, followed by Noelle (accidentally knocked by the impact), Susie, and Kris (following Noelle).

Sans makes her final appearance in the chapter at the Holidays' residence, preventing the heroes from escaping through the Grey Door. She makes another lunge for Kris's SOUL before punching Susie to the ground. She then reveals a sadistic story from her past: her attacking and killing this world's version of Susie (who is named Suzy). Out of rage, Kris jumps up behind her and stabs her in the shoulder with their knife, dealing four hits of 120 damage before Sans shakes them off. Afterward, Sans engages the heroes in a boss fight.

There are five different outcomes to Sans's battle depending on your last action in the fight:

If Sleep Mist is used, Sans tries to threaten the heroes before falling asleep. Susie tells Kris that she was about to kill Sans herself, but the three heroes decide to move on anyway. However, Sans suddenly mumbles in her sleep, causing Susie to draw her weapon and prepare to kill her. Papyrus will then suddenly enter to stop Susie from killing her, and lament about how Sans used to be comedic and friendly before she turned into a cold, jaded killer, and brutally attacked him for not killing people. Papyrus decides to quit his aspiration of becoming a Royal Guard and hopes that one day Sans will return to the way she used to be.

Alternatively, if Sleep Mist is used in the Obliteration Route, Sans will express surprise that Kris is sparing her despite the massacre they committed and the torture they put their teammates through. She reflects on how evil she's become, but even that is still nothing compared to Kris's actions. She gets up and walks off to sleep somewhere else, leaving the three to stew in their decisions. Susie then turns to Kris and is just barely stopping herself from ripping out Kris's SOUL. She tells Kris that this is the one time killing someone would've been justified, but the SOUL let the "orphan killer" live just because it also kills kids. She then grabs Kris and yells about how the orphan was her (and depending on your actions, will mention how you already tried to kill her anyway). Noelle will then shout at Susie, causing her to calm down. She then notes that sparing Sans will prevent the massacre from escalating any further, and that they will no longer draw blood. Susie then decides to move on, but not before expressing her severe hatred for the SOUL.

Sans can also be Talked to repeatedly. At first, she will refuse to talk at all, but continuing to question her will cause her to reveal that she couldn't bring herself to finish Suzy off, despite how much she looked like the Deltarune Susie. She then laments over how awful her life had become, and felt the only way to make the world better would be to destroy it, so she began a murderous spree to gain LOVE. She observes Papyrus's refusal to see the world from her point of view, before holding her head in horror as she realizes the evil she committed and the abuse she put her brother through. She buries her face in her hands, before losing her Hostility once and for all. Papyrus suddenly enters, much to Sans's shock, and scolds her for becoming part of the problem and throwing everything to the wayside for her narrow-sighted goal, to the point of almost killing a child. Sans, experiencing incredible guilt, feels as if there is no way to make amends for her actions and that she doesn't deserve a second chance, let alone deserving to live, but Papyrus encourages her to try anyway, and offers to help her as they both have a long path to atonement to walk down, before helping her up. Sans then asks Papyrus about becoming a royal guardsman, but upon hearing Sans's confession, Papyrus has decided to cast that dream aside, as it is a title written in blood, and he wishes to help people instead of shedding even more. Sans accepts this, then jokingly tells Papyrus she hopes Undyne doesn't kill him for this. Papyrus then apologizes on behalf of the two brothers for putting the Delta Warriors through so much, especially Kris, and thanks them for helping him and his brother pursue a better path in life. The two brothers then leave to return home. Susie is still angry and believes Sans doesn't deserve forgiveness, but the three heroes move on anyway.

If attacked, Sans will have a diagonal slash down her chest and her jaw will fall off. In her final moments, she taunts Susie, telling her that this doesn't avenge Suzy and that her family didn't care that she's dead. She then laughs manically as Susie furiously attacks her, her body growing more and more mangled with every attack until she finally turns to dust.

If Iceshock is used, Sans seems significantly more afraid. She sits there, shaking due to the cold, murmuring in disbelief before she finally freezes over. Whether she is dead or trapped eternally in the ice is left unspecified, but due to her reaction, it is likely the latter.

If Susie is Devious, she will get angry, wondering how the SOUL would know that Sans would freeze over, and throws away the Heavy Branch, leaving her unarmed as the SOUL clearly doesn't need her (after forcing Kris to attack Susie and then making Noelle finish off Sans).

Either way, the Delta Warriors jump through the Grey Door after finishing the battle, leaving the world of GG!Underfell behind.

Power and abilities: Bone Manipulation Blue Soul Magic Skeleton physiology Gaster Blasters Levitation Super Strength Pyrokinesis (seemingly) Teleportation Flight via jetpack

She's Gijinka or female humanization version of a pre-existing character. She's currently 32 years old here.