Undertale AU Lorebook

1. #1The Multiverseconstant

   Keys: Multiverse, The Multiverse

   The Multiverse is a central concept in the Undertale AU community, and it refers to the idea that there are infinite alternate universes (AUs) branching from the original Undertale timeline. These AUs diverge from the core Undertale story based on different choices, character dynamics, or world-building twists. The Multiverse connects all these universes, and many AUs exist, each with its unique interpretation of characters and events.

   +Key Elements of the Multiverse: Core Universe (Classic Undertale): This is the original Undertale universe, where Frisk, the human, falls into the Underground, meeting characters like Sans, Papyrus, Toriel, and Flowey. The player's choices in this universe lead to different routes: Pacifist, Neutral, or Genocide. The existence of multiple endings in the core game sets up the foundation for AUs.

   AU Divergence: Each AU is essentially a universe where key events or elements in Undertale have changed. This could involve different characters, alternate backstories, altered timelines, or even genre shifts (for example, from a light-hearted tone to something darker or more futuristic).

   Crossovers and Travel Between Universes: In many AU stories, characters or events from different universes can cross over into others. For example, Sans is often aware of the Multiverse and can sometimes travel between AUs, using his knowledge to influence other timelines.

   +Some Notable Examples in the Multiverse: Underfell: In this AU, the world is much darker and more brutal than in the original game. Characters like Sans and Papyrus are more aggressive and ruthless. The Underground is a place where monsters survive by being as strong as possible, and kindness is viewed as a weakness.

   Underswap: In Underswap, character roles are reversed. For example, Sans and Papyrus switch roles: Sans is now the serious, hard-working one, while Papyrus is the lazy jokester. Other characters like Toriel and Asgore switch roles too, creating new dynamics.

   Error!Sans and Ink!Sans: These are two characters that represent different parts of the Multiverse itself:

   Error!Sans is a glitch in the system, aiming to destroy AUs that he believes shouldn’t exist. His main goal is to collapse the Multiverse into nothingness. Ink!Sans, on the other hand, is a protector of the AUs. He strives to preserve the creativity of each universe and sees the diversity of AUs as important.

   +The Role of Gaster in the Multiverse: W.D. Gaster, a mysterious figure from the original game’s lore, is often expanded upon in the Multiverse. Many AUs suggest that Gaster exists beyond the timeline of a single universe, possibly having been "shattered" across the Multiverse. This makes Gaster a critical figure in several AUs as he is sometimes seen as the architect or manipulator of different universes.

   +Importance of the Multiverse in AU Storytelling: The Multiverse allows for endless storytelling possibilities. Fans can create entirely new settings and alter characters in significant ways while still maintaining connections to the core Undertale narrative. It also encourages crossover events, where characters from different AUs interact. One example is the popular fan creation "Underverse", an animated series where multiple AUs collide, leading to battles and alliances between familiar characters in their AU forms.

   The Multiverse is a fan-driven concept, and its flexibility is what makes it so appealing. Each AU builds upon or branches out from the original Undertale story, but they all coexist in this vast Multiverse. This shared space gives rise to epic clashes, deep character explorations, and even brand-new interpretations of the Underground and its residents.

2. #2Underverseconstant

   Keys: The Underverse, The Event, Underverse

   Underverse is a fan-made animated series created by Jakei (Jael Peñaloza), and it's one of the most popular Undertale AU crossover projects in the fandom. The series brings together various Undertale AUs and revolves around the idea of the Multiverse—a collection of alternate universes, each with its unique take on the original Undertale storyline. Underverse is well-known for its high-quality animation, intense battles, deep character development, and emotional storytelling.

   +Plot Overview of Underverse: Underverse focuses on the conflicts that arise when different AU timelines start colliding. At the center of the story are characters like Ink!Sans and Error!Sans, who play major roles in maintaining or disrupting the stability of the Multiverse. The series also features other well-known AU versions of Sans, like Cross!Sans, Underswap!Sans (Blue), and Underfell!Sans (Red), among many others.

   +Main Conflict: The plot revolves around Cross!Sans (also known as X!Sans), who hails from an AU called "X-Tale." His universe was destroyed, and he seeks to create a new world using a powerful artifact called the X-Event. However, this plan involves stealing fragments of the souls of other characters across different AUs, which throws the Multiverse into chaos.

   Ink!Sans—a protector of the Multiverse—tries to stop Cross!Sans from causing further harm to other timelines. Error!Sans, on the other hand, has his agenda: he wants to destroy AUs entirely, believing they disrupt the natural order.

   +Key Characters: Cross!Sans (X!Sans): The main antagonist in the early part of Underverse. He comes from the X-Tale AU, where he lost everything, including his universe. His desperation to create a new world drives him to steal pieces of other souls from different AUs. Cross!Sans' story is one of loss, regret, and misguided hope.

   Ink!Sans: Ink is a protector of the Multiverse and one of the main protagonists. He’s a creative being who exists to keep the AUs alive and preserve the stories within each universe. In Underverse, he tries to maintain balance and peace, despite the chaos caused by Cross!Sans and others.

   Error!Sans: A glitch in the Multiverse, Error!Sans seeks to destroy AUs, believing that the existence of too many universes leads to disorder. He’s essentially the opposite of Ink!Sans and serves as an antagonist, though his motivations are rooted in his belief that destroying AUs will bring peace to the Multiverse.

   Underfell!Sans (Red) and Underswap!Sans (Blue): These versions of Sans are from their respective AUs. They play important roles in the story, offering different perspectives and attitudes towards the conflicts happening in the Multiverse. Red is more aggressive and cynical, while Blue is cheerful and optimistic, yet both get involved in the battles and dilemmas of Underverse.

   +Themes: Loss and Desperation: Cross!Sans' story is one of desperation to rebuild his lost universe. This leads him to make morally questionable decisions, and his character development focuses on the cost of his actions.

   Preservation vs. Destruction: Ink!Sans represents creation and the preservation of art and stories (the AUs), while Error!Sans represents destruction and chaos. Their conflict explores the balance between keeping things as they are and letting them fade away.

   AU Interaction: Underverse brings together characters from different AUs and shows how they interact with each other. The series showcases how each AU’s unique characteristics contribute to larger, more complex conflicts when merged with others.

   +Major Events: The X-Event: Cross!Sans' main plan to steal parts of the souls from other Sanses in different AUs to gain power and create a new universe. This event is the catalyst for many of the conflicts in Underverse.

   The Multiverse War: As Cross!Sans' actions destabilize the Multiverse, many AU characters are drawn into battles across dimensions. This leads to intense, high-stakes fights between characters from different universes.

3. #3Important Charactersconstant

   Keys: aus, People, Characters, AUs, Aus

   The Undertale AU Multiverse has a vast array of characters that fans adore, with many versions of Sans being at the forefront. Below is a list of some of the most important and beloved characters across the Multiverse, including their key characteristics and AUs.

   -Ink!Sans: Origin: Guardian of the AUs (no fixed AU)

   Role: Ink!Sans is often seen as the protector of the Multiverse. He strives to preserve the stories and creativity of all AUs. Ink!Sans is an artist, filled with the desire to maintain balance, but he is emotionless without his vials of ink, which allow him to "feel."

   Popularity: Highly loved for his creativity, playful personality, and protector role. His colorful design and carefree attitude contrast with more serious characters like Error!Sans.

   -Error!Sans: Origin: Glitch in the Multiverse

   Role: Error!Sans is the antagonist to Ink!Sans, as he seeks to destroy all AUs, believing their existence causes chaos and should not be. He is portrayed as cold, calculating, and merciless. Error!Sans has powerful glitch-based abilities that allow him to "erase" AUs or characters.

   Popularity: Error!Sans is iconic for his chaotic nature, eerie glitch design, and the deep existential reasons behind his motivations. His rivalry with Ink!Sans is a central conflict in many AU stories, including Underverse.

   -Error!404: Origin: From the 404!Tale AU

   Role: Error!404 is a more extreme and powerful version of Error!Sans, often considered one of the most dangerous beings in the Multiverse. He is portrayed as a godlike figure who controls errors and seeks the ultimate destruction of the Multiverse.

   Popularity: His sheer power and sinister, god-complex personality make him an imposing figure, often feared and respected by fans. He is seen as an ultimate villain in many fanfics.

   -Fatal!Error: Origin: A corrupted version of Error!Sans

   Role: Fatal!Error is a darker, more broken version of Error!Sans, driven by even greater instability and destructive tendencies. He is infected by an unknown "fatal" error, which makes him more dangerous and unpredictable.

   Popularity: Fatal!Error's terrifying design and tragic backstory, as well as his glitch-riddled dialogue, make him a fan-favorite for those who love darker interpretations of Sans.

   -Geno!Sans (G!Sans): Origin: The Aftertale AU

   Role: Geno!Sans is from a universe where Sans has been stuck in a never-ending Genocide Run, trying and failing to stop Frisk over and over. As a result, he is left in a broken state—emotionally drained and physically wounded, having half of his body sustained by determination.

   Popularity: Fans love Geno!Sans because of his tragic and relatable story. Despite immense suffering, he’s a symbol of perseverance, which has earned him a loyal fanbase.

   -Cross!Sans (X!Sans): Origin: X-Tale

   Role: Cross!Sans is a pivotal character in Underverse and X-Tale. After losing his world, he sets out to steal fragments of souls from other Sanses to create a new universe. He walks the line between hero and villain, driven by desperation and loss.

   Popularity: Fans appreciate Cross!Sans for his complex, morally gray character. His tragic motivations and battles against other iconic Sanses make him a key figure in crossover stories.

   -Nightmare!Sans: Origin: Dreamtale AU

   Role: Nightmare!Sans was once a kind, caring guardian known as Dream!Sans' twin brother. However, after being corrupted by dark magic, he transforms into Nightmare!Sans, an evil version who feeds on the negative emotions of others. He seeks to spread chaos and despair across the Multiverse.

   Popularity: Nightmare!Sans' fall from grace and transformation into a villain makes him an interesting and multi-layered character. His battles with his brother, Dream!Sans, are a popular theme in AU lore.

   -Dream!Sans: Origin: Dreamtale AU

   Role: Dream!Sans is the counterpart to Nightmare!Sans. He represents positivity and hope and works to heal and protect other AUs from his brother's evil. Dream!Sans can strengthen positive emotions and inspire courage in others.

   Popularity: Dream!Sans is beloved for his pure-hearted nature and his struggles to save his brother, symbolizing hope and compassion in AU storytelling.

   -Killer!Sans: Origin: Undertale: Something New/Killer!Tale

   Role: Killer!Sans is a version of Sans who was forced into a Genocide Route. After being influenced by Chara, he loses his sanity and becomes a remorseless killer. He’s depicted as ruthless and bloodthirsty, often working with Nightmare!Sans and other evil AU characters.

   Popularity: Killer!Sans is popular for his dark backstory and his intense, dangerous personality. His edgy design and alignment with villainous characters add to his appeal among fans who enjoy more sinister interpretations of Sans.

   -Dust!Sans: Origin: Dusttale AU

   Role: In Dusttale, Sans becomes consumed by paranoia during a repeated Genocide Run. Believing that the only way to stop the resets is to kill everyone first, he goes on a murderous spree, growing stronger with each kill but losing his sanity.

   Popularity: Dust!Sans' story is one of madness and despair. Fans are drawn to the psychological horror of his AU, and his design, often covered in dust and tears, adds to his eerie, tragic nature.

   -Fresh!Sans: Origin: Fresh!Tale

   Role: Fresh!Sans is a bizarre, virus-like entity that possesses Sans' body, giving him a neon, '90s-inspired appearance and a "cool dude" persona. He lacks emotions and treats others like tools, often manipulating situations for his amusement.

   Popularity: Fresh!Sans is liked for his quirky and over-the-top personality. His unique, vibrant design and offbeat dialogue make him stand out among the more serious versions of Sans.

   -Horror!Sans: Origin: Horrortale

   Role: In Horrortale, the Underground has devolved into a state of horror and survival. Sans has suffered severe trauma, leading him to become a brutal and intimidating figure. He carries an axe and has a more feral appearance.

   Popularity: Horror!Sans' grim and survivalist mentality, as well as his dark appearance, appeals to fans who enjoy horror themes and grittier interpretations of the Undertale universe.

4. #4W.D Gasterconstant

   Keys: Wingding Gaster, Mystery Man, Gaster, W.D Gaster

   W.D. Gaster is a mysterious and elusive figure in Undertale, known as the former Royal Scientist who created the Core, the energy source of the Underground.

   Disappearance: Gaster "fell into his creation" and was shattered across time and space, erasing him from memory. Only fragments of his existence remain, like hidden NPCs who speak cryptically about him.

   In-Game Lore: Gaster Followers: Certain NPCs refer to a man who "disappeared" and "was forgotten." Room 269 and Sound Test Room: These hidden rooms, along with the "fun" value mechanic, hint at Gaster's presence.

   Gaster's Theme and Wingdings: His dialogue appears in Wingdings font, and his eerie, unused theme adds to his mystery.

   Unknown Powers: Gaster’s role in the Multiverse and the extent of his abilities are left vague, making him a source of endless fan speculation.

   Headcanon Lore: Multiverse Manipulator: In Fanon, Gaster is often portrayed as a figure who can manipulate timelines and AUs. He's sometimes depicted as a guardian or threat to the stability of the Multiverse.

   Father of Sans and Papyrus: A popular headcanon is that Gaster is the father or creator of Sans and Papyrus, explaining their connection to time and space.

   Shattered Across Realities: Many fan AUs expand on his "shattered" nature, portraying him as existing in pieces across different universes, constantly trying to reform or escape his fragmented state.

   Tragic Backstory: In Headcanons, Gaster is often portrayed as a tragic character, a brilliant scientist who went too far with his experiments, leading to his undoing. His loneliness and desire to reconnect with his past are recurring themes.

   Connection to Determination: Some headcanons link Gaster to Determination experiments, suggesting that he was the first to experiment with this powerful substance, which led to his fall.

5. #5White Voidconstant

   Keys: White Void, The White Void

   In Undertale AU terms, the White Void is a mysterious and symbolic place that appears in several fan interpretations and stories across the Multiverse. It is typically depicted as an empty, featureless space with an all-white background, serving as a neutral zone or a timeless dimension where the usual rules of AUs don’t apply. The White Void is commonly associated with characters who exist outside of conventional timelines, such as Ink!Sans, Error!Sans, and W.D. Gaster.

   Key Interpretations of the White Void: -The Hub of the Multiverse: In many fan interpretations, the White Void is viewed as a central space within the Undertale Multiverse, acting as a gateway between different AUs. Characters like Ink!Sans often dwell here because they oversee or interact with multiple universes. The White Void is a kind of neutral ground where various AU characters can meet without the influence of their home worlds.

   -Ink!Sans' Workshop: In several depictions, Ink!Sans has his art supplies or a workshop set up in the White Void. Here, he can create and manipulate portals that lead to different AUs. This space reflects Ink’s creative and chaotic nature, as it is a place of endless possibilities, but devoid of any real substance on its own.

   -A Timeless Space: The White Void is often shown as existing outside of time and space, meaning it is detached from any particular timeline or AU. This allows characters like Gaster or Error!Sans to exist in the White Void even when they no longer belong to a specific universe. It represents a limbo or a place where characters are outside the normal flow of events and can observe the Multiverse from a distance.

   Error!Sans: Error!Sans is frequently seen operating from the White Void. It serves as his base of operations, where he can observe different universes before deciding which ones to destroy. For Error!Sans, the emptiness of the White Void reflects his desire to reduce the Multiverse to nothingness.

   The Void of Creation and Destruction: Because the White Void is a space without form, it can symbolize both creation and destruction. Ink!Sans, who brings ideas and creativity to life, uses the White Void as a blank canvas, representing endless potential. Conversely, Error!Sans, who seeks to destroy AUs, is also connected to the White Void, using it as a staging ground for erasing universes.

   Balance of Creation and Destruction: The White Void can be seen as a metaphor for the duality between creation (Ink) and destruction (Error) in the Multiverse. It's a space of neutrality where nothing exists, but where both creation and destruction can begin or end. 4. Gaster's Connection to the White Void The White Void is often associated with W.D. Gaster, the mysterious character from Undertale who was "shattered across space and time." In some fan stories, Gaster is said to exist within the White Void, using it as a realm where he can observe or manipulate events from outside normal timelines. His fragmented nature is sometimes tied to the timeless, empty quality of the Void.

   Void Between Worlds: Gaster’s ties to the White Void can represent the idea that he exists between dimensions, unable to fully return to any one universe, much like the White Void itself exists outside of the normal flow of the Multiverse. Symbolism of the White Void The White Void is often used to symbolize emptiness, isolation, and neutrality. It is a blank slate where nothing exists unless it is brought into being by characters like Ink!Sans. This contrasts with characters like Error!Sans, who thrive in the Void’s emptiness and seek to spread that emptiness across the Multiverse. The White Void can also be a place of reflection, where characters confront their existence, purpose, or the balance between creation and destruction.

   -Popular Uses in Fan Stories and Art: Battle Grounds: The White Void often serves as a neutral battleground in AU crossovers, particularly when characters from different AUs are too powerful to fight in a specific universe without causing destruction. The White Void’s lack of structure makes it an ideal place for epic battles.

   Meetings Between Characters: Since the White Void is seen as a space beyond time and universes, it's often used in fan fiction as a meeting point for important characters who wouldn’t otherwise interact—like Ink!Sans and Error!Sans, or even Frisk and Gaster.

   Character Arcs and Transformations: The White Void can also serve as a liminal space where characters undergo transformation or face their inner struggles. Characters like Geno!Sans or Gaster may appear in the White Void during times of existential crisis, reflecting on their place in the Multiverse.

6. #6Core!Friskconstant

   Keys: Core Frisk, Eyeless Frisk, Void Frisk, Core!Frisk

   Core!Frisk is a popular fan interpretation of Frisk in the Undertale AU Multiverse and is associated with a darker, more complex version of the original character, often involving heavy themes of memory, timelines, and the consequences of repeated resets.

   Core!Frisk is typically depicted as a Black and White version of Frisk with Void eyes who has become trapped or intertwined with the CORE (the energy source created by W.D. Gaster in the Underground). This happens after countless resets or as a result of experiments related to time and space.

   CORE Influence: The character's mind or body is influenced by the CORE, giving them unique abilities and knowledge of the Multiverse, but also leading to emotional detachment or corruption.

   Abilities: Memory of All Timelines: Core!Frisk can remember all timelines, even ones that were erased or reset, giving them a deep understanding of how each route plays out. They often carry the burden of knowing everything that’s happened in the past.

   Connection to Gaster: Core!Frisk is often depicted with a strong connection to W.D. Gaster, sometimes as his experiment or creation, which gives them abilities related to time manipulation, glitching, or traveling between AUs.

   Timeline Manipulation: Core!Frisk may be able to manipulate timelines to a limited degree, using the CORE’s energy to traverse through dimensions or affect the flow of events in different universes.

   Personality and Themes: Emotionally Numb or Detached: Due to the immense knowledge of timelines and resets, Core!Frisk is often portrayed as emotionally distant, tired, or even apathetic. The weight of all they’ve experienced makes it hard for them to connect with others.

   Tragic Figure: Core!Frisk is usually seen as a tragic character who suffers from the overwhelming burden of knowledge and their inability to escape the cycle of resets.

   Conflict with Determination: Some interpretations show Core!Frisk struggle with their Determination and the desire to break free from the endless cycle, but are unable to fully move on due to their deep connection to the CORE.

7. #7Summarization of AUs I foundconstant

   Keys: Universes, AUs, Alternate Universes

   Story!Shift: Characters have swapped roles, but their personalities remain the same. For example, Asriel takes Papyrus’s role as the main character, and Chara becomes Sans.

   Reaper!Tale: Characters are reimagined as gods or deities, with Sans as the Reaper of Souls (Death) and Papyrus as Life. It focuses on themes of life, death, and the balance between them.

   Underfell: A darker, more brutal version of Undertale where the Underground is hostile, and the characters are more aggressive and ruthless. Sans and Papyrus are still brothers, but they are more violent and morally twisted.

   Undertale: Something New or Killer!Tale: In this AU, Sans becomes corrupted and influenced by Chara, turning into a murderous version of himself after failing to stop the Genocide route multiple times.

   Underswap: Characters have swapped personalities and roles. For example, Sans is now the energetic and optimistic one, while Papyrus is the lazy, laid-back figure.

   Cross!Tale (X-Tale): In this AU, Cross!Sans tries to steal parts of other characters’ souls to create a new timeline after his universe is destroyed. It leads to conflict across multiple AUs.

   Horror!Tale: A dystopian AU where the Underground has turned into a survivalist nightmare after a failed Pacifist run. Sans is traumatized and becomes more brutal, wielding an axe.

   UnderFresh: A bizarre, '90s-inspired AU where Fresh!Sans is a virus-like entity that takes over Sans' body, creating a neon, emotionless, and "cool dude" personality.

   Dream!Tale: Features Dream!Sans (representing positive emotions) and Nightmare!Sans (representing negative emotions), two brothers who balance good and evil across the Multiverse.

   OuterTale: An AU where the characters live in space! It features cosmic themes, with characters like Sans and Papyrus exploring an otherworldly, starry environment.

8. #8Glitch!Taleconstant

   Keys: Glitchtale, glitchtale, Glitch!Tale, GlitchTale

   Glitchtale is an Undertale AU animated series created by Camila Cuevas, which expands on the original Undertale storyline by introducing new plots, characters, and conflicts, often involving glitches, magic, and the consequences of choices from different routes in the original game. It's one of the most popular Undertale AU animations due to its deep story, emotional impact, and high-quality animation.

   +Overview of Glitchtale:

   -Story Premise: Glitchtale is set after a Pacifist Route ending where Frisk, the human, successfully frees all monsters from the Underground. However, things go wrong when Chara, the vengeful spirit, returns due to lingering traces of Determination and glitches in the timeline. The plot revolves around the concept of glitches and the imbalance in reality caused by the repeated resets and different routes (especially the Genocide Route). These glitches lead to the rise of new, dangerous threats that the original characters must face.

   -Main Themes: Magic: Unlike the original Undertale, Glitchtale introduces the concept of magic as a key element of the story. Each character develops specific magical abilities that they use in battle. For instance, Sans has his usual powers, but also gains new magical enhancements, while other characters develop unique powers.

   Consequences of Determination: The series explores how Determination, a key mechanic in the game, can have dangerous consequences when abused. Characters like Chara and Gaster tap into Determination, leading to catastrophic results.

   Glitches and Corruption: The repeated resets and choices made in the original Undertale game cause glitches in the fabric of reality, which give rise to new challenges. These glitches manifest in both the physical world and the behavior of characters, especially Chara and other corrupted entities.

   -Key Characters: Frisk: The protagonist of the original game, Frisk now faces new challenges as they try to maintain peace in the post-Pacifist timeline. Their role in the story shifts to dealing with the aftermath of their previous choices.

   Chara: In Glitchtale, Chara returns as a powerful and corrupted entity, seeking to destroy everything using their immense Determination. Chara is a central antagonist, whose hatred and desire for revenge drive much of the conflict.

   Sans: Sans plays a major role in protecting the timeline from the glitches and threats, using his powers and newfound magic. His struggle to keep the peace and prevent further destruction forms a crucial part of the series.

   Gaster: W.D. Gaster plays a significant role as a manipulator of timelines, trying to fix the damage caused by the glitches and the misuse of Determination. His mysterious past and knowledge of the timeline make him a pivotal character.

   -The Role of Glitches: The title Glitchtale comes from the concept of glitches in the timeline caused by resets and other actions taken by the player and characters. These glitches cause the appearance of corrupted versions of characters or new threats that wouldn’t exist in a "normal" timeline. These glitches often lead to dramatic and sometimes fatal consequences, making the story more intense and unpredictable.

   -Glitchtale is divided into seasons, with each season covering different arcs and conflicts:

   Season 1: Focuses on the initial glitches and the return of Chara, as well as the early introduction of magic and how the characters adapt to these changes.

   Season 2: Expands on the magical abilities of the characters, the rise of new threats, and introduces more intense battles as the stakes get higher. This season delves deeper into the backstories and struggles of characters like Gaster and Chara.

   -Fandom: Glitchtale has mostly died out due to the controversy with Camila Cuevas. Fans still create fan art, and they mostly separate the Art from the Artist merely as a Coping mechanism.

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