In a specific timeline, long ago, a few of the disbanded Human wizards that sealed monsters underground began a new group, secluded from the rest of the humans, moving in the shadows, never quite revealing what their plan was...
In the year 200X, the child of the leader of the wizards fell into the world of the monsters, the only parent she stayed with was her father, who had always treated her badly, however, her mother and her wife, whom she had cheated on the father with, because of his personality, she just wasn't happy.
~'Disclaimer: This story has a lot of profanity and covers some very very intense or touchy subjects that may disturb some readers. You have been warned.'~
((Unedited))
After Chara fell into the Underground, they met Asriel a monster inhabitant of the Underground. Soon after that, Chara joins a new family, but their ambition to keep everyone happy goes a little overboard and Chara is flung into a reality of destruction and hopeless wonder. Then many long years later they meet the beloved Frisk, who fell into the Underground, similar to themselves. Eventually everything Chara thought they knew correctly is turned upside down and they as a person are changed forever.
~'The game Undertale belongs to Toby Fox and some of the dialogue is ripped straight from the game itself, too.'~