The author of this story requested me to not repost this story. Instead, I'm putting the link in the first chapter. It's a really good story with AU jumping, Sans, Frisk, and a whole lot of great characters. It's one of my favorite stories I've ever read. And now, the description, taken straight from the actual story.
After a harrowing trip through Underfell, Frisk is nearly ready to go meet King Asgore. Their adoptive brother and good friend Sans would rather they go anywhere else-anywhere at all, as long as they don't get to that throne room. After all, in this world, it's kill or be killed.
That's just this world, though. How about the next one over?
DISCLAIMER: This does not belong to me. Neither does the cover.
~'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.'~