PART 1 of making Deltarune versions of popular UndertaleAUs. {DREAMRUNE}
Not 100% sure if this counts as Undertale AU still tbh
There is a Tree.
A tree of Light A tree of Dark
A tree of Hope A tree of Dreams
Hidden away in a secluded small town, the Tree of Light grows. It is protected by the Vessel of the Light. Its branches are filled with Soulfruit. When a soulfruit falls to the ground a Lightner is born. Once a century, the tree grows a dark soulfruit, and the door to the Dark World opens, when the fruit falls and the Prince of the Darkness is born. He is taken into the Dark World by the Vessel of the Light, and a new Vessel exits.
When December Holiday's father Rudy becomes deathly ill, she steals a soulfruit in the hopes that it will heal him, but before she manages to get home, the Vessel of Light finds her.
Before the Vessel sees that Dess took the fruit, Dess eats it. She manages to get home with only a minor scolding, but in her SOUL a deep hunger has taken root, after eating a soulfruit, all other food seems completely unappetizing.
Dess's actions did not go entirely unnoticed. The door to the Dark World opened soon after, several decades too early, and a new immature, vessel wandered out.
With the dark soulfruit not yet grown, the Vessel of Light takes the next Soulfruit to fall into the Dark World.
When the Vessel returns, without the child, but unsuccessful in completing the cycle, blame falls onto the immature vessel.
The kindly Dreemur family takes in the child and names him Kris. As the years pass, the door to the Dark World stays open, albeit constantly guarded by the Vessel. With human Soulfruit being exceedingly rare, and Hometown being a small place, everyone knows that Kris is the immature Vessel. Kris is ostracized. The other children refuse to play with him, and sometimes will go as far as to attack him or throw things at him.
Dess being the only one who knows why the Dark World opened early felt incredibly guilty for the way Kris was treated. She made efforts to befriend the five year old and his older brother, she also introduced him to her younger sister, Noelle who was around his age.
With Rudy worsening, Dess convinces herself to make another attempt on the Soulfruit. This time, she brings Kris to distract the Vessel of Light.
While picking the fruit, Dess is unable to hold back her hunger, and she begins to eat them. The Vessel realizes what is happening too late, and is unable to reach Dess before she eats the immature Dark Soulfruit.
Empowered by the fruit, and taking the Vessel by surprise, a delirious Dess attacks and fatally wounds the Vessel before fleeing into the Darkworld.
The Light, now without a body, takes the form of a human soul and claims Kris as its new Vessel. It forces Kris to chase Dess into the Darkworld.
One of Kris's bullies- Susie- sees Kris go into the Darkworld and chases after him. The door shuts behind them.
In the Darkworld, under the Tree of Darkness, Kris and Susie meet Ralsei, the false prince of darkness, now unable to leave the Darkworld despite being a Lightner by birth.
He tells them that a strange figure had come through the door before them, they follow him in the direction it went.
An out of control Dess plants several 'Dark Saplings' which threaten to bring about the Roaring if they grow to maturity. Kris, now housing the light, is the only one who can destroy the saplings.
The trio of children set off (reluctantly, in Susie's cause) in the hopes of saving Dess, and both worlds.