Undertale: The Chara's Route

Once upon a time, two races ruled over the Earth: Humans and Monsters. One day, war broke out between the two races. After a long battle, the humans were victorious. They sealed the monsters underground with a magic spell. The humans' fear of monsters was based mainly on the monsters' ability to absorb human SOULS. Trapped underground, the monsters explored their new environment and slowly set up a kingdom there and society
In the year 201X a human child called Chara fell into the Underground. How did she fell there ? What's gonna happen to her ? This is a story about her route.

This story should have 4 parts / 4 arcs, maybe 5 but the last one will be probably called as bonus part.
The story of my au is fanfiction based on game called Undertale, made by amazing Toby Fox.
To all Undertale fans, this universe has entirely new logic for souls. Save and Load does exist in this universe along with reset, but not like you're used to see Frisk or Chara with these abilities. Be patient please and try to understand, because in this AU is most of things different :)

image in background : https://www.deviantart.com/garucca415/art/Once-Upon-a-Time-UNDERTALE-SPOILERS-687572491