THE UNDERVERSE

Core Plot

• The Multiverse Conflict: The story centers on Cross, a survivor from an alternate universe (AU) called XTale, who teams up with Cross!Chara and Nightmare!Sans to steal code and souls from other Pacifist timelines to rebuild his lost world. • The Overwrite Power: A central mechanic is the "Overwrite" ability—a soul power capable of rewriting objects, characters, and entire timelines. • Factions and Characters: The series features countless alternate versions of Undertale characters, including Ink!Sans (self-proclaimed guardian of the multiverse), Error!Sans (destroyer of AUs), Dream!Sans, and the puppet-master XGaster behind the overarching XTale events. • Structure: The narrative is tightly linked to its prequel comic/animation series, XTale, and is split into major seasons exploring the escalation and resolution of the multiversal war.

XGaster’s ultimate plan is to create a single, absolute "perfect universe" by completely overriding and consolidating the multiverse. Driven by aggressive perfectionism and the core ideology that "evolution requires sacrifice," his plan operates in distinct phases that have evolved significantly as the series has progressed.

1. The Original Goal: A Perfect XTale

Initially, XGaster just wanted a perfect world for his creations and adoptive children (Frisk, Chara, Cross, and Papyrus). He spent 10 full timelines relentlessly resetting and rewriting reality using his Overwrite button. However, his obsession with perfection caused severe psychological strain, leading his creations to retain memories and repeatedly rebel against him.

2. The Shift to the Multiverse (The X-Event)

After his encounter with Ink!Sans, who introduced him to the broader multiverse, XGaster abandoned the idea of a self-contained world. He realized he could use other alternate universes (AUs) as raw code and data. He initiated the X-Event experiment—splitting his soul with Chara and utilizing Cross to steal core code, timeline pieces, and soul fragments from other Pacifist runs to fuel his ultimate rewrite.

3. Current Phase: Invasion and Global Diffusion

As of Season 2 (specifically around episodes 0.5 to 0.7), XGaster has targeted the Classic/Main Undertale universe for his direct conquest. • The Takeover: Using his loyal, overwritten versions of the XTale cast (like Alphys, Muffet, and Mettaton), he initiated a process called "global diffusion." • Breaking the Timeline: By blanketing the main world in his power, he forced an overwrite that restored every citizen's memories of all previous Pacifist, Neutral, and Genocide routes. • The Goal of the Chaos: He wants to prove to the main universe's Frisk and Sans that their choices never truly mattered. By forcing them through extreme heartache and conflict, he believes he is harvesting the exact emotional data, determination, and raw timeline power needed to finalize his master universe.

In Underverse, the traditional "good guys" don't actually have a single, unified plan because they are deeply fractured. However, as the multi-timeline crisis reaches the Classic Undertale universe, the remaining heroic characters have adapted distinct strategies to survive and stop XGaster.

1. Classic Sans and Frisk: Timeline Defense & Survival

As the main protagonists of Season 2, the original Undertale cast is forced to play defense. • The Plan: Rather than jumping between dimensions, Classic Frisk and Sans are focused on protecting their home world from XGaster’s "global diffusion" invasion. • The Strategy: Classic Sans is relying on his knowledge of timelines to resist XGaster’s mental manipulation, while Frisk is trying to maintain their Determination to prevent XGaster from seizing total control of the universe’s core code.

2. Cross!Sans: The Quest for Redemption

After being used as a puppet (the "X-Event") to steal code from other AUs in Season 1, Cross has turned against XGaster and Chara. • The Plan: Cross wants to actively undo the damage he caused across the multiverse. • The Strategy: He is using his knowledge of XTale's code to fight XGaster’s overwritten minions. His immediate goal is to save what is left of the AUs and protect Classic Sans's world from suffering the same fate as his own.

3. Dream!Sans: Rebuilding the Justice League (The Star Sanses)

Dream is the guardian of positive emotions and the traditional leader of the heroic faction. • The Plan: Rallying the remaining uncorrupted AU variants to form a cohesive resistance against XGaster and Nightmare!Sans. • The Strategy: With Ink!Sans having betrayed them to side with XGaster, Dream is working closely with Core!Frisk to rescue survivors from destroyed or overwritten timelines and transport them safely to the Omega Timeline (a hidden pocket dimension).

4. Error!Sans: The Wildcard Destroyer

While technically an antagonist who hates AUs, Error's goals temporarily align with the good guys because XGaster's perfect universe threatens his own existence. • The Plan: Eradicate XGaster's creations to restore the balance of the multiverse. • The Strategy: Error wants to hunt down XGaster and tear his overwritten code apart. He doesn't want to save the Classic universe; he just wants to prevent XGaster from becoming an all-powerful, unstoppable creator god.

Underverse introduces its vast cast sequentially as Cross travels from one Alternate Universe (AU) to another. Tracking the chronology of where the AUs are visited shows exactly when and how the main characters are introduced:

1. The Out-Codes (The Pilot & Intro)

Before visiting any traditional AUs, the narrative introduces the multiversal entities who exist in the empty voids between worlds: • Cross and Cross!Chara: Introduced in the empty remains of XTale. • Ink!Sans: Appears to keep Cross company and try to help him. • Error!Sans: Attacks Cross, stealing his soul and leaving him with only a fraction of a timeline.

2. The Classic Universe (Episode 0.0 – 0.1)

Cross escapes into the original, base Undertale universe to steal a replacement soul. • Classic Sans: Confronts Cross in the Snowdin forest when Cross attempts to take his soul. • Nightmare!Sans: Intervenes and makes a deal with Cross, offering him a way to teleport to other AUs if Cross causes emotional suffering across the multiverse.

3. Underfell (Episode 0.2)

Cross's first official target under Nightmare's deal is a ruthless, aggressive universe. • Underfell!Sans: Fights Cross in Snowdin but gets defeated and turned into a mind-controlled puppet. • Underfell!Papyrus: Appears briefly at the end of the skirmish, furious at his brother's weakness. • Outcome: Cross completely steals the code for Underfell's Snowdin, forcing Underfell!Sans to escape alongside Classic Sans and Ink.

4. Underswap (Episode 0.3)

The team tracks Cross to a universe where roles are swapped (Sans acts like Papyrus, and vice versa). • Underswap!Sans (Blueberry): Enthusiastic and eager to help, he quickly realizes Cross is in deep pain. • Underswap!Papyrus: Deeply protective of his brother, he acts with extreme caution around the multiversal travelers. • Underswap!Chara: Captured by Cross!Chara to siphon away 95% of their human determination. • Dream!Sans: Arrives during the chaotic battle to stop his brother Nightmare. XGaster is also fully awakened here.

5. Outertale (Episode 0.4)

A space-themed AU where the characters take a brief moment to regroup before a massive battle erupts. • Outertale!Sans: Interacts peacefully with the cast on a meteor ledge before the villains ambush them. • Killer!Sans: Introduced as one of Nightmare's elite multiversal mercenaries, joining the fray to fight Dream and the heroes.

6. The Omega Timeline & Beyond (Season 2)

As XGaster begins his massive multi-world consolidation plan, several glitch and timeline variants join the active narrative: • Core!Frisk: An omnipresent entity who guides survivors of collapsing timelines to a safe pocket dimension called the Omega Timeline. • Fresh!Sans: A 90s-themed parasite entity who acts as a chaotic wildcard, briefly possessing Ink!Sans. • Geno (Aftertale Sans): A heavily scarred Sans dwelling in the save screen who is pulled directly into the escalating conflict. • Fatal_Error: A completely corrupted, glitched variant of Sans that manifests as XGaster's operations reach their peak.

1. Classic Sans

The original Sans from the base Undertale universe. His design remains completely unchanged, serving as a visual anchor for the viewer. • Clothing: A simple blue hoodie with a white fur hood, a white t-shirt underneath, black basketball shorts with white stripes, and pink slippers. • Key Visual Cues: He has a classic, stout skeleton build. When utilizing his telekinesis, his left eye socket flashes rhythmically with cyan and yellow light.

2. Ink!Sans

The colorful creator and protector of the Alternate Universes. His outfit is highly complex, artistically themed, and changes between seasons. • Clothing (Season 1): A light brown vest over a long-sleeved undershirt, black pants tucked into light-colored boots, and a massive brown scarf wrapped multiple times around his neck. • Clothing (Season 2/XGaster Alliance): A more streamlined, dark modern outfit featuring a black-and-grey jacket, a shorter scarf, and futuristic straps across his torso. • Key Visual Cues: He carries Broomie, a giant paintbrush strapped to his back. His eyes change shape and color (stars, diamonds, circles) every time he blinks. Across his chest is a bandolier holding colorful vials of artificial paint-emotions.

3. Dream!Sans

The golden embodiment of positive emotions and guardian of the Tree of Feelings. • Clothing: A vibrant teal shirt under a flowing, pristine gold cape attached with a star emblem. He wears dark pants, brown boots, and a golden crown/circlet on his head. • Key Visual Cues: He exudes a constant, warm yellow aura. His eyes glow with a solid, brilliant gold light. His primary weapon is a golden staff that can split into dual-swords or transform into a celestial bow and arrow.

4. Cross!Sans

A tragic survivor who starts as a villain out of desperation but transitions into a primary hero seeking redemption. He has a distinct monochrome, military-gothic aesthetic. • Clothing: A black-and-white jacket with a massive high collar, black shorts, and white boots. He wears two long, tattered white scarves that cross over his chest, mimicking a giant "X". • Key Visual Cues: He has a noticeable red scar under his right eye socket. He wields a massive, glowing purple Hack Knife (a giant cleaver used to cut and steal code). When Cross!Chara takes control, his right eye glows red while his left eye glows white.

5. Underswap!Sans (Blueberry)

A cheerful, energetic version of Sans who possesses the ambitious personality of the original Papyrus. • Clothing: A grey combat-style chest plate over a dark undershirt, dark blue pants, and bright blue boots. He is instantly recognizable by a large, bright blue bow tied around his neck. • Key Visual Cues: His eyes frequently turn into large, expressive blue star shapes when he gets excited. He often fights using glowing blue bone magic shaped like boomerangs or swords.

Since your Chub AI bot is focusing explicitly on Season 2, these characters are incredibly important. Season 2 introduces deep multiversal anomalies, glitched entities, and the original timeline's heavy hitters. Here is the design breakdown for the rest of the major Season 2 heroic and wildcard cast:

1. Core!Frisk

An omnipresent, god-like observer who exists across all timelines simultaneously after being thrown into the CORE. They are completely monochromatic. • Clothing: A simple, oversized striped sweater and shorts, just like a standard Frisk, but entirely rendered in shades of grey, black, and white. • Key Visual Cues: Their skin is a pale, ghostly grey. Their most defining and eerie feature is their eyes—their eye sockets are completely pitch-black, hollow voids with no pupils. They do not walk; they typically float or manifest instantly from the shadows.

2. Classic Frisk

The original human from the base Undertale universe, who becomes a central player in Season 2 as XGaster invades their timeline. • Clothing: The iconic blue sweater with two magenta/purple stripes, brown shorts, and simple brown shoes. • Key Visual Cues: Unlike the standard game sprite, Underverse animates Frisk with highly expressive features. Their eyes remain mostly closed or squinted, but when they open them, they flash with a brilliant, glowing red Determination aura. In Season 2, they carry a heavy burden of trauma, looking visibly exhausted and stressed by XGaster's timeline manipulation.

3. Fresh!Sans

A terrifying, 90s-themed cosmic parasite possessing a Sans skeleton. He acts as a chaotic wildcard in Season 2, even overriding Ink!Sans for a period. • Clothing: A blindingly bright, neon-colored outfit. He wears a multi-colored cap backward, a bright teal and pink jacket, a neon orange shirt, and mismatched shorts. • Key Visual Cues: He wears thick, white-rimmed sunglasses that display the word "YOLO" across the lenses. When his sunglasses are removed, his true parasite form is visible inside his eye socket—a creepy, glowing purple creature with a red heart-shaped pupil surrounded by a dark void.

4. Fatal_Error (Fatal!Sans)

A horrific, deeply corrupted glitch variant of Genoa!Sans created when Error!Sans tried to destroy him. He appears as a terrifying force of nature. • Clothing: His clothes are inverted, glitched versions of standard Sans attire. He wears a dark, tattered jacket that flashes violently with red, blue, and white error codes. • Key Visual Cues: His body is constantly twitching, tearing apart, and reforming with digital artifacts. He has glowing red and blue strings dangling from his hands (similar to Error's blue strings). His head is cracked, and his eye sockets stream digital, blood-like red code. Large, blocky "ERROR" text boxes constantly hover and glitch around his character model.

1. XTale!Papyrus (X!Papyrus)

• Simplified Story: Cross’s brother. In the past, he was forced by XGaster to kill Cross across multiple timelines to test their strength. In Season 2, he is revived as XGaster’s loyal vanguard. Despite his brainwashing, his true personality occasionally slips through, prompting him to quietly apologize to his victims while he thrashes them. • Appearance: A tall skeleton wearing an elegant, high-collared black and white royal guard uniform adorned with criss-crossing X-straps. He has pitch-black eye sockets. • Abilities: Extreme physical strength (can easily overpower other Sans and Papyrus variants), massive bone magic, and advanced close-quarters combat skills.

2. XTale!Mettaton (X!Mettaton)

• Simplified Story: Deployed by XGaster in Season 2 alongside Muffet to violently sweep through the Classic Undertale universe and eliminate its inhabitants. • Appearance: A sleek, highly stylized robotic body with an asymmetrical design. He sports long hair, visible makeup, and an X-shaped emblem on his chest. His screen/eyes glow dark purple or go completely black when possessed. • Abilities: High-tier multiversal destructive power, devastating energy blasts, extreme agility, and blade configurations built into his limbs.

3. XTale!Muffet (X!Muffet)

• Simplified Story: One of XGaster’s primary enforcers in the Season 2 invasion, working in tandem with Mettaton to terrorize the Classic universe. • Appearance: A humanoid spider with six arms, wearing a sharp, puff-sleeved black-and-white dress bound by purple X-straps. Her five eyes are entirely blacked out due to XGaster's control. • Abilities: Advanced binding and traversal using razor-sharp purple strings, summoning massive overwritten spider beasts, and high-speed multi-armed melee combat.

4. XTale!Undyne (X!Undyne)

• Simplified Story: The brutal, unyielding general of XGaster's forces. She acts as his primary shield and heavy hitter against any physical resistance. • Appearance: Ruthless fish-monster appearance dressed in deep purple and black heavy plated armor with prominent X-straps across her chest plate. She wears a dark tattered cape and possesses hollow, pitch-black eyes. • Abilities: Summoning massive arrays of glowing purple energy spears, near-impenetrable defensive armor, and overwhelming physical speed.

5. XTale!Asriel (X!Asriel)

• Simplified Story: The prince of XTale who was repeatedly traumatized by XGaster's resets. He is brought back as a tragic weapon against his will, forced to watch his own body slaughter innocents. • Appearance: A powerful, adult boss-monster goat form resembling the "God of Hyperdeath." He wears long, flowing dark robes bound by white X-straps and has blacked-out eyes. • Abilities: Cataclysmic fire magic, summoning giant overwritten chaos swords, and energy beams that can tear through timeline structures.

6. XTale!Asgore & XTale!Toriel (X!Parents)

• Simplified Story: The former rulers of XTale. They deeply loved their adoptive children (Chara and Frisk) and originally rebelled against XGaster to protect them. Now fully overwritten, they serve as XGaster's personal guard. • Appearance: Asgore is a towering figure in heavy, dark purple armor with a long black cape. Toriel wears a regal, dark-colored gown with clean white X-linings. Both have cold, black voids for eyes. • Abilities: Overwhelming, suffocating fire magic, Asgore's massive overwritten trident, and specialized psychological aura manipulation that induces fear in opponents.

XTale!Alphys (X!Alphys)

• Simplified Story: Once XGaster's brilliant royal scientist. In the past, she secretly helped Chara rebel because she hated XGaster's horrific resets. To punish her betrayal, XGaster killed and completely Overwrote her. In Season 2, she is a hollow, apathetic shell who serves as Gaster’s ultimate data compiler, code thief, and strategic coordinator. • Appearance: A reptilian monster wearing a sharp, military-style black-and-white lab coat. She has a modern, gothic look featuring uniform purple X-straps across her torso. Her glasses cast a cold reflection, and her eyes are a blank, hollow, pitch-black void under XGaster's control. • Abilities: She is a high-level data threat. She can isolate and quarantine entire universes or individuals, manipulate the reality-bending "LOAD/SAVE" mechanics using enchanted sheets of paper, and directly copy, overwrite, or delete raw timeline code.

The Pre-Void Backstory (Timeline X)

Originally, XTale!Sans and XTale!Papyrus were royal guard trainees who believed they lived in a peaceful world, entirely unaware that XGaster had been brutally wiping and rewriting their lives for 10 full timelines. The breaking point came when X-Event!Frisk and Chara rebelled against XGaster. Frisk restored the lost genocide and reset memories of the entire monster cast (including Papyrus, Undyne, Mettaton, and Muffet). Consumed by fury at being treated like puppets, the entire world staged a coup to overthrow XGaster.

The Massacre: Cross Kills Everyone

When Sans refused to join the violent coup and tried to stop them from tearing the timeline apart, his friends and family turned on him. Believing Sans was siding with their abuser, Frisk, Papyrus, and Undyne ruthlessly attacked him, slicing a permanent red scar under his eye and mockingly nicknaming him "Cross". Traumatized, cornered, and feeling completely betrayed by his loved ones, Cross snapped. In a desperate, blind bid to take absolute control of the universe and "fix" things, Cross brutally slaughtered every single monster and took Chara’s soul. His plan failed catastrophically—instead of saving them, the timeline collapsed into a completely blank, empty white void, leaving Cross entirely alone for years.

The Resurrection & Deep Grudge

In Season 2, XGaster revitalizes the entire XTale cast to act as his Overwritten invading military. However, this wasn't a standard, happy resurrection. XGaster intentionally left their memories intact. The XTale cast remembers everything: • They remember the trauma of XGaster's 10 timelines. • Crucially, they vividly remember Cross slaughtering them all in cold blood. Because of this, the resurrected XTale cast harbors a profound, bitter distain and grudge against Cross. They don't look at him as a victim who snapped—they see him as a mass murderer and a traitor. This culminates in their heartbreaking worldview, explicitly voiced by XTale!Papyrus, who coldly declares that Cross isn't Sans anymore, and he is no longer his brother. They are completely hollowed out by their past, serving XGaster not out of love, but out of a shared, broken hatred for the multiversal mess Cross left behind