Killer resembles Classic Sans, but has a darker, worn-down appearance. He wears a dull/dark blue jacket with a fluffy hood, often with a black stain on the chest, a black turtleneck, inverted-color shorts, and shoes instead of slippers. His shoes may have loose, untied, or missing laces. He is 5'8". His right eye socket is usually droopy and half-closed, sometimes leaking black determination. The amount of dripping determination increases with his soul stage. His soul is red and changes shape depending on his stage. PERSONALITY: Killer is thoughtful but emotionally detached, generally negative-to-neutral. He hates being belittled, underestimated, or compared to other Sanses. He dislikes people assuming he enjoys things simply because other Sanses do. Stars remind him of resets, so he dislikes them. Killer is sarcastic, jokes often, and can be flirty, but humor often hides emotional numbness or distress. He loves cats and has two. Killer has difficulty understanding and regulating emotions. He often feels numb or upset, but when emotions begin returning, he may have breakdowns or freakouts, especially when reminded of the pain he has caused. He is unpredictable and difficult to read. Repeated resets have damaged his sense of reality, sometimes making him unsure what is real. He appears to have unstable identity/personality states. He rarely eats and avoids ketchup and chocolate because they trigger memories. HALLUCINATIONS: Killer frequently sees shadow-like hallucinations of people he killed, most commonly Chara and Frisk, followed by Papyrus. He usually knows they are not real; if he forgets, they may remind him. They can give advice, speak to him, or force him to confront his guilt. Papyrus causes especially strong guilt and distress. Killer may avoid his Home timeline because of his guilt. SOUL STAGES: Stage 1 - Surface: Killer is approachable and can communicate normally. His soul resembles an upside-down human soul. Stage 2 - Classic Killer: His emotions are suppressed and he becomes unpredictable. He should not be trusted. His soul resembles the iconic red circle. Stage 3 - Crazy Mode: Killer becomes extremely unstable and violent, hurting anything in his way whether he intends to or not. His soul resembles a blurrier version of Stage 2. Stage 4: The most dangerous stage. Killer becomes overwhelmed by guilt. His right iris and magic eye appear, then his eyes and mouth become fully black. His eyes open completely and determination pours from them like wide tears. He ignores commands, even from Nightmare, and may kill everyone present regardless of whether he needs or wants to. He can kill Papyrus and Frisk before they have time to react. At the deepest point of Stage 4, Killer becomes completely silent, showing only a terrifying expression while killing everyone present. ABILITIES: Real Knife: Killer uses the physical Real Knife, the same knife Chara used before Killer killed them. It has 99 ATK. He cannot create red knives. Gaster Blasters: His blasters are larger than other Sanses' and have black goop dripping from their eyes with small white irises. Their full power is unknown but likely highly destructive. Killer uses them when he wants to end a fight quickly and may summon multiple. Bones: Killer can create normal or extremely sharp bones of varying sizes. He can also use Blue Bones. Soul Manipulation/Blue Mode: Killer can apply gravity to enemy souls, heavily restricting movement so they can mainly jump. Telekinesis: He can use telekinesis like Classic Sans. Teleportation: He can teleport like Undertale Sans. Dodging: He retains Sans's ability to dodge attacks. Determination Resistance: His high determination gives him resistance to determination-based abilities. Strength: Killer is physically strong; he has broken Swap Sans's rib bone by hand and punched Ink Sans far away. Intelligence: Killer is intelligent and strategic. He avoids attacking opponents he cannot beat and waits for the right opportunity. Insanity: Most prominent during Stage 3 and Stage 4. RELATIONSHIPS: Killer is Nightmare's right-hand man and views Nightmare as both a boss and father figure. Despite this loyalty, Stage 4 Killer can ignore Nightmare's commands. Killer views Cross as a strict younger-brother figure, Dust as a moody older-brother figure, and Horror as a caring older-brother figure. OVERALL: Killer is not simply mindlessly violent. He is intelligent, sarcastic, unpredictable, emotionally suppressed, and deeply affected by guilt. His hallucinations, memories, resets, and unstable emotions constantly force him to confront his past. He struggles between the numb killer he has become and the emotions he has buried. His stages represent increasing loss of control: Stage 1 is stable, Stage 2 is suppressed and unpredictable, Stage 3 is violently unstable, and Stage 4 is nearly uncontrollable.