What happend after?
Frisk got found by Toriel, the caretaker of the Ruins. After Toriel made sure that Frisk was healthy again, she made it her task to teach Frisk how to live with monsters and solve their puzzles.
Despite Frisk liking Toriel and the area they are in, they are still worried about where their siblings are and whether they are okay.
Kris got taken in by Rose, the Lady of the Mines. Under Rose's command, everything is in order, and everyone in the mines has a job they have to follow. Just like everyone else, Kris has the task of helping Rose around the house in exchange for food and shelter. Rose may be strict, but she makes sure Kris doesn't lack anything.
Despite the safety Rose provides, he is scared, not knowing what happened to his siblings.
Chara got picked up by Valerian, the protector of the Catacombs. He is someone who looks after everyone here and makes sure to help with any problem there might be. Thanks to his specialty in plant magic, he managed to bring certain flowers to life to help with his daily tasks and keep him company.
Despite the kindness Chara receives from everyone in the Catacombs, she doesn't feel happy without her siblings.
I dont own either undertale, Deltarune, underfell or underswap.
Undertale and Deltarune belongs to @TobyFox
Underfell belongs to @underfell
Underswap belongs to Popcornpr1nce