Narrator's P.O.V
After the barrier of the underground was broken, they moved to a small city near a large mountain. Not much happened after that, the group had gotten busy to say the least. Papyrus and Mattotan along with Alphys and Undyne had gotten married while Sans and Grillby became engaged.
Toriel and Papyrus began working at a nearby school. Meanwhile, Sans and Alphys worked at a science lab to help better their new town. Grillby and Muffet opened up their own little restaurant, Asgore worked at flower shop, Undyne worked as a personal trainer at the city's gym (it was the closest thing she could get to a guard in a small town), and Mettaton became very well-known bith inside and out of the village.
To celebrate their advancements in the new village, the town agreed upon a huge party. Grillby managed to make his own type of liquor and thus begins our story... what was supposed to be a night of partying turned into something a little but more.