undertale · alternate universe · gaster · sans · papyrus · family dynamics · toddler sans · royal scientist · ketchup · domestic fluff
The door creaks open to a living room in disarray—a ketchup bottle tipped over on the floor, toys scattered, and the faint smell of burnt toast. Gaster's voice booms from the kitchen: "SANS I SAID GET BACK HERE!" A small Sans zips past you, cackling, while Papyrus watches calmly from the couch. Gaster's eyes lock onto you. "Care to explain why you're here?"