*Have you thought about a world where everything is exactly the same...
*Except you don't exist?

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Asgore Dreemurr
* Golly, this sure is terrible

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Deltatale is an AU where the characters and locations of Deltarune take place in Undertale, causing the darkners to be trapped down in the Underground instead of the Monsters.

Character Roles

  • Frisk- Kris
  • Flowey- Jevil
  • Sans- Susie
  • Papyrus - Lancer
  • Undyne- TBA
  • Alphys- TBA
  • Toriel- Ralsei
  • Asgore- Chaos King
  • Mettaton- Rouxls Kaard/K.Round
  • Napstablook- C.Round
  • Chara- TBA
  • Gaster- TBA
  • Muffet- TBA
  • Grillby- Seam
  • Nice-Cream Guy- Top Chef
  • Snowdin Shopkeeper- Tutorial/Puzzles Guys



Taking the place of 'Frisk', Kris is the same as the Hometown form of the character. They are unnameable as in 'Deltarune' but use the same fighting style, menu options and inventory as the original Undertale.


Ralsei is the Toriel alternative in this AU. He is similarly loving and caring as her but retains his personality and 'fluffiness' from Deltarune. He loves baking cakes, making manuals and scarfs. Ralsei lives in his own home at the end of the Castle Ruins in which are the signs of the previous lighteners who fell down into the Darkground. Ralsei cares for Kris, fearing he will not survive against the other darkeners, who own a resentment against the lighteners for their fate, but he lets Kris pass when Kris shows he holds the power within him to proceed. Themes: Fallen Legend, Unnecessary TP, Empty Heart.


Susie is the Sans of this AU and has a very black sense of humor. She makes gruesome jokes and doesn't do her jobs but instead eats food all day and beats people up. She greets you with a strong shove in to the wooden bridge in Fielden and warns you about her bad guy partner Lancer. She appears multiple times and sells things like Chalk and punches. Themes: susie., Theme That May Start When You Piss Off Susie, Aggression.
Undertale text box (2)
Undertale text box (3)


Lancer is Papyrus as a spade son of a spade king. He makes 'Thrash Machines', puzzles and teams of assailants to try and stop the main protagonist. He wants to be a real 'scary bad guy' but is to not scary for him to join the 'Scare Guard'. His appearance is that of a Lancer Papyrus, whatever it means. Lancer also has an obsession with salsa, which he makes but not very well. Themes: Ho Ho Ho!, Spadetrousle, Thrashing Start!, Thrashing Tense!, Thrashing Fight!.


The first Darkner met by Kris and the most chaotic villain of the story, Jevil remarks constantly on the 'freedom' he has found and the longing want for does around him to be 'free' too. He resembles Flowey with petals as joker hats with bells on the end, and with Jevil's face from Deltarune. Themes: Your Friend That Can Do Anything.

Chaos King

The Ruler of the Darkground is the Chaos King, slayer of lighteners. His desperation for revenge against them abandoning him and Darkners alike fuels his intent to see the end of anyone who falls down into the Darkground. The King takes Asgore's place and retains his design from Deltarune. Instead of Asgore's Trident, King uses his spade shaped tongue as his signature weapon and destroys the mercy button with it during the beginning of his boss fight. Themes: KING.
Undertale text box-0

Rouxls Kaard

Mettaton is replaced by Rouxls Kaard in this AU. He is a charismatic and well spoken Puzzle-Master-Extraordinaire, who uses his 'brilliant' puzzle making skills to make various popular tv shows for his Darkner audience. In design he resembles his Deltarune design, with a few changes to appear slightly more robotic. His 'transformation' turns him into a hybrid of K.Round and himself. Themes: It Beith Puzzle Timeth!, Worm Crusher, Hip Report, THOU WORM! Report, Oh! Thou True Worm, Finaleth Puzzle!, Oh Thy..., Vanquish via Puzzles.


C.Round is this AU's version of Napstablook. He love to dance and whistle and even make tunes for him to dance to. His appearance is a ghostly checker-piece. Themes: Checker Fight, Checker Tune, Checker Wave, Boardiday, Thrill, Checkersnail


The owner and bartender at Seam's diner, Seam is the alternate of Grillby. His shop has a rustic feel and is decorated with the junk and weapons he has collected over the years. He resembles his look from Deltarune, but wears a bartender suit and his right eye is a button monocule.

Minor Characters

Top Chef

Top Chef is runs his own cake vendor which he sell his marvellous cakes to the Darkground. However, he keeps his vendor away from the relentless Susie, who constant tries to eat/destroy his cakes as they are her enemy.

Tutorial/Puzzle Guys

Runs a Tutorial and Supply Shop in Fielden after being forced not the make puzzles when Rouxls Kaard took over.

Mr. Society

Mr Society replaces the Politics Bear in Snowdin. Instead of Politics, he is heavily concerned with how the society of Fielden Town behave.

Mr. Elegance

Mr Elegance replaces....

Trash Can Rudinn

A Rudinn invited into a trash can in amongst the junk piles.


Castle Ruins

The Castle Ruins are the ruins of the old Castle Town which sat at the front of the Darkground when the Darkners were first banished. After some time, the Darkners left and expanded into other areas of the Darkground. This left those such as the 'Prince of Darkness' to roam its lonely walls. It is very similar to the Ruins in Undertale, but much darker and like the Castle Town of Deltarune. Themes: Castle Ruins.


The windy fields that are home to the town of Fielden is a popular spot for several darkners to live. The popularity of Dark Candy and 'Thrash Machines' attracts tourism from several Rudinns (who lack any other sort of fun). Instead of the snowfall, Fielden has the fall of leaves from its scarlet trees and the ground is covered with the long grass. The wind can be a problem for the smaller darkeners, who tend to blow away. Themes: Breezy, Fielden Town.


The rustic style diner is considered the centre of Fielden Town. The menu of Darkburgers and Dark Fries are the draw of the restaurant's many customers. Members of the Scare Guard are often seen their playing cards or observing the many ancient weapons and junk that are hung around the walls.


The Backstory of Deltatale is different to Undertale in several ways. The Darkeners and Lighteners lived in peace on the Surface until one day the Lighteners saw the Darkeners baffling resistance to damage and powerful attacks and became afraid of their potential. And so a coalition of the Humans and Monsters banished the Darkeners to the Darkground, and used Seven Lightner Souls (four of which were Monster and three of which were Human) to create the Fountain. The Fountain kept the Darkeners in the Darkground and all hope was dependent on the Four Kings's decision.

The Kings founded their new kingdom and made it as good as they could for their trapped people, but they eventually had to hold council to decide what is to be done. At first the suggestion is that they should accept any lighteners who fall into the underground as friends to help destroy the Fountain, but out of the four kings, the King of Spades refused this idea, imbittered by the forcing of his people underground. He argued and eventually killed the three other kings and took the throne. Many who were part of the court, such as Ralsei, left, horrified by the actions of the ruthless King, and hid away. The King was left to rule, not harshly but with the rule that any lightner which fell into the Darkground, would be slain.

Ralsei left the court of the King and set up home in the Castle Ruins, a once lifeful town which the Darkners first lived in but left after deciding to move to new homes. Susie, a lightner, did fall down into the Darkground, but instead of being slain, but kept it mostly a secret as to keep safe (or by scaring off all the troops sent after her.)

Main Story

Deltatale begins with Kris (The alternative for Frisk) falling in to the 'Darkground' in the year 201X. They fall into the 'Castle Ruins' and encounter the seemingly harmless joker Jevil (The alternative for Flowey). After running through the ways of the "Trapped World" of the Darkground, Jevil attacks Kris, who is only rescued by Ralsei (The alternative for Toriel). Ralsei states that they are the lonely dark prince who watches over their ruined home of the Castle Ruins and always keeps an eye out if any Lightners fall down into the Darkground. He leads Kris through the Castle Ruins and teaches with various 'Tutorials' how to manage their way through the Darkground. After passing through the Castle Ruins and reaching his castle home, Kris has to make the decision to leave and progress forward in their journey. But Ralsei stands in their way, warning them on the dangers of the other Darkeners and how they will never get past the 'King'. Ralsei is forced to fight Kris. After finishing the battle, Kris proceeds out of the Castle Ruins and into the next location.

Kris enters into Fielden and ventures forward until encountering a bullyish figure. This figure turns out to be Susie. She was meant to be on patrol for Lightners but being one herself, a monster, she doesn't care less. She greats Kris violently and tells them about her team partner Lancer and how he is desperate to capture a Lightner.


Castle Ruins Enemies:


Rudinns take the place of Froggits. They use various diamond attacks and have a care free nature.


Hathys take the place of Whimsuns. Hathys have a tendency to be quite shy and their heart attacks show them as lovers, not fighters. They will often wish not to enter into combat and will flee after being flirted with.


Taking the place of Vegatoid, Rabbick offers you a dry off of wind to keep you 'air dried'. Rabbick cackles and smiles mysteriously but struggles with a strong breeze.

Fielden Enemies:


Jigswary's take the place of Snowdrake in this AU. They are very overdramatic and so struggle to find friends with other darkeners. Jigsawry's stick together often as they share each others over done opinions on this and that.

Unknown Location Enemies:


Replacing Aaron, Bloxer likes to keep in shape by boxing and demonstrating his physical strength, but often ends up in several pieces.


Replacing Knight Knight, Ponmen have a love of lullabies and tend to fall asleep when hearing one. Sleep can however make them rather bad Scare Guardsmen, as they tend to nap on duty.

Note: Instead of location based, enemies are placed in according to similarities with Undertale enemies rather than area placement.

Potential Music Themes

A growing list this AU's Soundtrack.

001. Once Upon Another Time

002. Beginning Menu

003. Your Friend Who Can Do Anything

004. Fallen Legend

005. Castle Ruins.

006. Uwa!! So Darkness♫

008. Unnecessary TP

009. Rude Buster Approaching

010. Checker Fight

011. The Power Of...

012. Town

014. Empty Heart

015. susie.

016. Ho Ho Ho!

017. Breezy

018. Uwa!! So Hopes and Dreams♫

022. Fielden Town

023. Tutorial

024. Spadetrousle

025. Thrashing Start!

026. Thrashing Tense!

027. Thrashing Fight!

032. Chase!

038. Checkertune

039. Checkerwave

040. Boardiday

041. Thrill

042. Checkersnail

049. It Beith Puzzle Timeth!

050. Worm Crusher

051. Anothereth Mediumeth

057. Hip Report

058. THOU WORM! Report

061. Oh! Thou True Worm

066. Finaleth Puzzle!

067. Oh Thy...

068. Vanquish via Puzzles

071. Deltatale

072. Theme That May Start When You Piss Off Susie

075. Fountain

077. KING

089. Save the Revolving World

099. Power of ROUND

100. Aggression

Sub AUs


The fell of Deltatale with a violent Lancer, a four armed Rouxls Kaard and a kinder Chaos King.


With such things as Susie with Rudetrousle, Lancer ready to give a bad time and Ralsei as ruler of the Darkground, what is not to like?

Deltatale: Disbelief

When Susie sacrifices herself for Lancer, and Lancer wants revenge for your actions.

Deltatale Revenge: The Unseen Ending

Lancer finds his true power with some help from the void to have revenge for Susie's death.


  • In the Genocide Route, Susie's attack includes Gaster Busters, the Deltatale version of the Gaster Blaster inspired by Susie's 'Rude Buster' attack in Deltarune.
  • The various Thrash Machines used by Lancer in Deltatale are a combination of the options for building the Thrash Machine in Deltarune and Papyrus's many puzzles in Undertale.
  • For the purposes of this AU, the Field of Hopes and Dreams and the Scarlet Forest are combined to form Fielden. (This is so it allows room for future Deltarune chapters to take place in this AU.)
  • Despite of Lancer's role in Deltatale he is still the son of the Chaos King. The relationship however is very distant, as in this AU he lives separately from his father.

Note: With the coming of the following chapters of Deltarune, many more things shall be added to this AU. Areas such as Waterfall and Hotland are not present yet as they do not yet have a replacement location, as well as Undyne and Alphys are not added. However, as soon as the next part of the game is released, all shall be added.