Just read the title. That explains everything. I had a really good summary typed out but Wattpad derped.
All rights to Undertale's characters go to mister Toby Fox and all the persons who worked on the project respectively.
Based around Toby Fox's Undertale all credit goes to him. In this Frisk is your best friend and Asriel was not able to free the monsters completely. He was almost able to break the barrier. Only humans can leave. Will this new person, who has mental issues, be their savior? If you want to know more you will have to read the story.