This AU takes place after the True Pacifist ending. One year after the monsters exited the underground, risk starts having strange dreams. She eventually realizes that these nightmares were about the other six children who fell into the underground, lost down there, and she goes with Toriel to see if they were true.
Other than the original characters of Undertale, the only characters in this AU are the resurrected Souls, they have fuzzy memories toward who killed them. The fastest way to get them to stop fighting you is to be wearing one of their items.
The soul of patience, she's the first human that fell after Chara and the first to be found by Toriel and Frisk. When she was killed it was because she was waiting in the ruins for Toriel and was found by a search party.
Randy is the orange soul of courage and can be found on the way to Snowdin and will immediately attack you and Toriel. Randy only remembers that a "Goat Monster" killed him, not which one.
Toriel and Frisk find Caron in Grillbys, basically trying to run it as a restaurant when no one was coming. She is the only one who won't battle you.