Killer

Biodata

Power Progression

Killer’s stages describe changes in her soul and personality, rather than a straightforward sequence of stronger forms 4.

Background / History

Killer attributes her past atrocities to her extraordinary determination, admitting that she sometimes cannot remember when she became this way. During Stage 2, she repeatedly visited other timelines to slaughter their inhabitants 3 5.

Under Nightmare, she worked to spread negative emotions and also moonlighted as an interstellar pirate. During a brief return to clarity, she studied her determination in a timeline’s True Lab and learned how to control her soul. Nightmare noticed the change and forced her back into Stage 2 before she could act on that knowledge 5 6.

After escaping his control, Killer adopted a new goal: preventing tragedies throughout the multiverse. The accidental overlap between her world and Dusttale concealed her from Nightmare among the parallel timelines, giving her an opportunity to stabilize her soul and recruit Murder 4 6.

By the time Insanity joins their travels, Killer counts three unfair contracts in her life: one with a human, one with Nightmare, and one involving Bill Sans’s future feast 39.

Appearance

• Build and face: A short woman with an attractive, youthful-looking face; Murder is taller than her, while Insanity is shorter 2 40.
• Hair: Snow-white 2 8.
• Clothing: Dresses much like Murder 3.
• Early appearance: Covered in more dust than Murder, with liquid determination pouring from her eyes 2.
• Stage 2: Black liquid flows from her eyes, and her exposed soul becomes circular 3.
• After stabilization: Her inverted-heart, target-patterned soul is surrounded by mist and covered in strange white code 6.

Personality

In Stage 1, Killer is conversational, teasing, and eager to help people escape tragic timelines. She offers to restore Murder’s world without requiring him to accompany her, respecting his choice to remain behind. Her sympathy comes from recognizing another version of herself tormented by a human 4.

Stage 2 replaces that restraint with intense curiosity and a willingness to kill. Killer describes this state as dangerous and untrustworthy; she warns Murder before losing control rather than concealing the impending transformation 3 4.

Her combat experience does not make her fearless. Sanstrosity’s appearance frightens her, and a previous fight with Insanity leaves her so alarmed that she draws her dagger upon waking beside her. She nevertheless agrees to help Insanity once she understands the situation 15 31.

Killer also recognizes when intervention has become too dangerous. Against the forces gathered around Error and Nightmare, she insists on helping the trapped Sanses one final time before retreating rather than staying in an unwinnable battle 30.

Abilities & Skills

Determination, Saving, and Resetting

Killer’s determination exceeds that of the humans she confronts, allowing her to deny their ability to load or reset while exercising those abilities herself 2 5 8 12.

• Save suppression: Prevents the Dusttale human from returning after death and warns the Last Breath human that he can no longer load 2 5 8.
• World restoration: Resets Dusttale and ULB’s universe to restore peaceful conditions 5 13.
• Strategic saving: Creates a save during the fight alongside ULB, then loads it after ULB dies to restore her and repair the world 9 12.
• Higher-dimensional limitation: The load restores the local world without affecting the higher dimension, leaving the human motionless. Killer admits this was her first attempt at the technique, making the outcome a successful gamble rather than a proven method 12.
• Missing-data limitation: Cannot reset the collapsing Underswap timeline because too much data is missing 27.

Soul Stages

Killer identifies her soul’s shape as a warning of her current mental state 4.

• External manipulation: Nightmare previously forced her into Stage 2; before treatment, she fears he could do so again with a casual squeeze 4 6.
• Soul stabilization: Her unconventional Extractor treatment is intended to prevent further soul alterations, not to cure the severe personality disorder she describes 6.

Knife Combat and Blade Energy

Killer uses a real knife with enough speed and precision to disarm the human before he can respond 2.

• Slices the human into several pieces almost immediately after disarming him 2.
• Performs eight slashes in less than a second while apparently capable of going faster 9.
• Channels blade energy through her small knife for precise ranged attacks 9.
• Uses slashing waves against Nightmare’s tentacle and to hold back masses of blue threads 26 30.
• Coats her dagger in a thin, blood-colored magical mist before fighting uv!Killer 32.
• Reaches a stalemate with uv!Killer because their matching habits prevent either from finding an opening 33.

Bone Magic and Blasters

Killer supplements her knife attacks with summoned bones and energy weapons 9 16.

• Precisely knocks the human into Murder’s sea of bones during their coordinated assault 9.
• Summons blasters alongside Murder to counter Sanstrosity’s reversed blasters 16.
• Breaks free of Murder’s blue-bone restraint without visibly moving, then evades his delayed blasts and specialized cannons 3.

Multiversal Travel

Killer can open spacetime rifts and use shortcuts to move within or between timelines 2 5 6.

• Takes Murder out of Dusttale and guides their subsequent travels 6 14.
• Opens escape routes during overwhelming battles 23 30.
• Previously fled through several universes before shaking off Insanity’s pursuit 31.

Soul-Trait Research

Killer learns enough about determination and soul alteration to operate the Determination Extractor herself 6.

• Studies her own determination during a brief period of clarity under Nightmare 6.
• Explains that the Extractor can remove soul traits, but warns that it processes one being at a time and may also take the target’s soul 44.
• Prepares the machine with Insanity and completes an extraction simulation while Murder and Lust obtain the needed trait 44 49.

Limitations

• Low durability: Has only 1 HP; she cannot afford the damage-trading tactics used by Insanity 31.
• Amalgamates: Knows her attacks are ineffective against the amalgamates surrounding the Dusttale Extractor 6.
• Overwhelming opponents: Treats Error and Nightmare as beyond the level at which she and Murder can safely intervene 30.
• Treatment risk: Her stabilization procedure uses dangerously high parameters and leaves her unconscious for three days 6.

Equipment / Weapons / Items

• Knife / dagger — Her primary weapon, used for close combat, defensive blocking, and projected blade energy 2 16 30.
• Rope — Carries rope and uses it to bind the defeated Bad Sanses 37.
• Savings — Money from her former interstellar piracy helps cover expenses for Murder’s little sister after he leaves 5.
• Determination Extractor — Laboratory equipment rather than a carried possession; used to stabilize her soul and later prepare targeted soul-trait extraction 6 44 49.
• Box pendant — Gives the pendant used during the Redemption Tale expedition to that world’s human protagonist before departing 23.

Relationships

• Murder — Traveling partner whom she recruits by offering to restore his world and help him seek atonement. He initially dislikes her because of her murderous past, but later credits her with saving ULB 4 6 12.
• Nightmare — Former controller and employer. He exploited her Stage 2 state to spread negative emotions; she escapes him and seeks to make her soul resistant to further manipulation 4 6.
• Insanity — Former opponent who once pursued her across several universes. Killer overcomes her fear sufficiently to help her fight Nightmare’s recruiters, then welcomes her into the traveling group 31 39.
• ULB — Fellow Sans whom Killer helps defeat a human, restores through loading, and befriends before resetting her universe 12 13.
• uv!Killer / UV Killer — A hostile version of herself, probably from an evil point in her timeline. Killer considers their fighting ability comparable, and their later duel confirms how closely their habits match 29 33.
• Bill Sans — Helps the group escape Nightmare after Murder accepts a deal requiring attendance at a future feast. Killer regards this as her third unfair contract 38 39.
• Lust — Local guide and collaborator in the attempt to remove the lust trait corrupting his Underground 40 44 49.
• Science Sans — Explains the Redemption Tale Entities to Killer and Murder and directs them toward another encounter 17.

Story Role / Major Arcs

• Dusttale: Kills the visiting human, encounters Murder during the timeline overlap, and relapses into Stage 2. After recovering, she resets his world, stabilizes her soul in the True Lab, and leaves with him 2 3 4 5 6.
• The Last Breath: Joins Murder and ULB against a human with modified HP. Her saved checkpoint restores ULB after death; she then kills the immobilized human and resets the universe 9 10 12 13.
• Redemption Tale: Investigates a corrupted Save Point and fights Sanstrosity, Papalgamate, and Xx_FRESHSANS_xX. She helps identify the strategy of satisfying an Entity before using the pendant to release its constituent souls, then returns the pendant to the human protagonist 14 16 19 21 23.
• Underswap / Poem of the Realm: A planned vacation becomes another conflict involving Nightmare and X-Chara. Unable to reset the collapsing world, Killer later helps cover a final rescue of Blue, Fell, and Classic before escaping with Murder 24 26 27 30.
• Triple Murder: Helps Insanity resist recruitment by the Bad Sanses and fights her own counterpart. After Nightmare intervenes and Bill Sans removes the threat, Killer helps reset Insanity’s world and accepts her as a teammate seeking redemption 31 33 38 39.
• Underlust: Flees the corrupted inhabitants, meets Lust, and helps prepare the Determination Extractor for the group’s plan to remove the invading soul trait 40 44 49.

Notable Quotes

“I... I'm about to enter Stage 2... Be careful of me when that happens...” 3

“Once upon a time, I was an executioner who collected negative emotions... Is this what helping others feels like?” 13

“We... travel through countless worlds, journeying across a sky full of stars... all to save those suffering in every world.” 41

Trivia

• Prefers ketchup-flavored chocolate to ordinary ketchup 16.
• Angrily tells the unexplained background music to stop when “Lethal Deal” begins playing during her proposal to Murder 4.
• Twice pauses her attack when uv!Killer shouts “Wait!”, frustrating Insanity, who is holding their opponent in place 36.
• Opens a rift and politely lets her teammates enter first, prompting Murder to compare her to an elevator operator 39.