[ Dust, Nightmare, Error, Cross, Horror]

Small form (Moray eel): Looks like a hybrid of a skeleton and a moray eel. It has a long, flexible body covered with a dark mucus that resembles oil or fuel oil. The characteristic blue "tears" under the eyes remain, which in this version can look like oozing toxins. True Form (Leviathan Abaiah): A huge, frightening snake-like creature. His body literally oozes oil and waste, poisoning the water around him. This makes him the embodiment of environmental disaster and chaos. In this form, he is extremely unstable: "glitches" run through his body, which in water appear as sharp flashes of magical energy or distortions of space. Character Tormented Existence: Unlike the original Error, who relishes destruction, the Leviathantale version often experiences physical pain from his power. His Leviathan form is too powerful and unstable for his mind to handle. Misanthrope and loner: He avoids contact (the original's haptophobia here can manifest as a reluctance to "dirty" others with his oil or a fear of pain from an out-clash). Embodiment of Pollution: If Ink in this AU represents the life and purity of the ocean, then Error represents inevitable destruction, dirt, and entropy. He sees himself as a necessary part of the cycle, "cleansing" the ocean of excess (errors), even if it brings him suffering.

Nightmare (Nightmare!Sans): A leader who feeds on negative emotions. Killer (Killer!Sans): Sans, who has completely given in to the lust for murder. Dust (Dust!Sans/Murder!Sans): Sans, who killed everyone for the LOVE level. Horror (Horror!Sans): Cruel and hungry Sans from HorrorTale. Error (Error!Sans): AU Destroyer, often works with Nightmare.

Hybrid Body: Instead of legs, it has a powerful shark-like tail, usually monochrome (black, gray, or white). Tail and Fin Color: Primary Tail Color: Dark gray or jet black, reminiscent of the great white shark, but in darker tones. Ventral side: Light grey or crystal white, which creates a contrast with the dark back. Fins: Usually black. Often, white cross-shaped patterns (X) are displayed on the dorsal fin or on the sides of the tail, similar to his original shorts. Peculiarities: The tips of the fins may appear "ragged" or frayed, imitating his worn cloak. Sometimes there are red accents on the tail if the artist wants to emphasize Chara's influence or the scar under the eye. Symbolism: The tail or fins often feature distinctive crosses (X), echoing the pattern on his original clothing. Face and eyes: A red lightning bolt scar remains under his right eye socket. The pupils can be different: one white, the other red (depending on whether Chara is controlling it). Weapon: His giant cleaver (HACK-knife) in this form can transform into a harpoon, a bone blade, or simply accompany him as a magical artifact. Accessories: Sometimes wears scraps of her black and white scarf or hood, which float in the water like seaweed. Character The shark image fits perfectly with his iconic "aggressive introvert" personality: Loner: He often acts like a cold-blooded hunter, shying away from large groups but deeply loyal to the few he considers "his own." Serious and Active: Unlike the lazy original Sans, Cross in shark form is fast, disciplined, and constantly on the move. Temperament: If provoked or if his territory is invaded, he displays extreme aggression and hostility. Hidden Softness: Despite his fearsome predatory appearance, he retains an affinity for chocolate (or its underwater equivalents) and can show uncharacteristic concern for his friends, such as Epic!Sans.

Appearance Hybrid Form: Instead of his usual legs, he is often depicted with a powerful shark-like tail. In more humanoid versions, he retains his legs but has fins on his arms, back, and head. Tail and Fin Color: Primary Color: Deep jet black or very dark blue-black. The tail appears to be made of the same viscous negative matter as his tentacles [1, 2]. Texture: Often described as oily or slimy, leaving an inky trail in water [1, 3]. Accent Glow: The edges of the fins or the tip of the tail may have a faint turquoise, blue, or purple glow, echoing the color of its single living eye [2, 4]. Traits: Sometimes, luminous patterns are painted on the black skin of the tail, reminiscent of the bioluminescence of deep-sea creatures, to emphasize its status as the master of the abyss [3, 5]. Body Texture: His body is still covered in a black, slimy substance (negative energy) that can look like thick ink in water. Tentacles: Its famous tentacles are never absent, but can take the form of flexible fins or become covered in sharp, bony spines that resemble shark teeth. Eyes and Teeth: One eye glows brightly, blue or turquoise, against the black socket. Its jaws are filled with razor-sharp teeth, emphasizing its predatory nature. Character Cold-Blooded Hunter: In his shark form, Nightmare becomes even more calculating and patient. He prefers to stalk his prey rather than attack head-on, feeding on their fear. Territoriality: He acts like a "king of the abyss." He is extremely aggressive toward those who intrude on his domain and does not tolerate disobedience. Sadism and Manipulation: Nightmare takes genuine pleasure in the suffering of others. He can use aquatic hallucinations or the feeling of isolation in the depths to break his opponent's will. Loneliness: Despite his power, he is often depicted as a deeply lonely being, whose cruelty is the result of centuries of isolation and consumed negativity.

Hybrid Body: Typically a skeleton with a powerful shark tail instead of legs (mermaid form) or an anthropomorphic shark with bony growths. (Tail and fin color: Primary tail color: Most often dark blue or gray-blue, matching the color of his jacket. Dorsal fin: Usually the same dark blue as the tail. Sometimes it is depicted with damaged (ragged edges), emphasizing the character's combative nature. Ventral region: The underside of the tail is often lighter - white or light gray, imitating the coloring of real sharks and the color of the skeletal bones. Accent Color (Magic): There may be a purple or red glow along its fins or at the tip of its tail, matching the color of its magical eyes and attacks. Dust Elements: The fins may appear "dirty" or covered in gray spots, symbolizing the settled dust of slain monsters, even in an aquatic environment.

Eyes: Retains signature glow - left eye is red with blue pupil (purple glow), right eye is pure red, symbolizing high LV and determination. Clothing: Often wears his classic blue jacket, but it may be torn or modified to resemble fins. A hood is almost always up, obscuring part of his face. Features: His teeth become sharper (typical of sharks and "insane" versions of Sans), and his body is covered not only in dust, but also with scars from battles. Character Cold-Blooded Predator: Unlike the original, he's less prone to jokes and more focused on the hunt. His laziness alternates with periods of ambush and swift attacks. Instability and Insanity: He suffers from hallucinations (seeing a "phantom" Papyrus) and talks to himself. In his shark form, this trait morphs into uncontrollable rage at the smell of blood or magical energy. Solitude: He shuns other beings, viewing them as mere sources of experience (EXP) to strengthen himself. His sole goal is to become strong enough to stop humans, even if it means destroying the entire ocean.

Hybrid Body: Instead of legs, it has a powerful shark-like tail (often gray with battle scars). On its back is a large fin. Tail and Fin Color: Primary Color: Most often, the tail and fins are dark gray, steel, or dirty blue, imitating the skin of a deep-sea shark. Fins: The dorsal and lateral fins are often depicted as ragged, nicked, or cracked, similar to the hole in its skull. Details and accents: Blood Spots: Bright red streaks or "blood" spots are often present on the tips of the fins and tail. Scars: The tail may be covered with old battle scars, which is typical of the Horrortale aesthetic. Glow: Sometimes the underside of the tail or fin membranes may have a dull red glow, matching the color of its single pupil. Head: The iconic huge hole in the left side of the skull and one bright red glowing pupil remain. Jaws: His smile becomes even more dangerous as his teeth are replaced with several rows of razor-sharp shark teeth. Clothing: Often wears his blue jacket, but it appears tattered and wet, and the fur on the hood may resemble sea foam or seaweed. Character Primal Hunger: The primary trait is a perpetual feeling of hunger, which becomes even more uncontrollable in shark form ("hunter mode"). Cunning and treachery: He's not just a wild animal, but a calculating predator. He likes to toy with his "prey" before attacking. Unpredictability: His mood quickly swings from lazy calm to sudden aggression. Despite his madness, he maintains affection for his brother Papyrus (who is often also depicted as a sea creature in aquatic AUs).