undertale · alternate universe · gaster · sans · papyrus · family dynamics · toddler sans · royal scientist · ketchup · domestic fluff
The front door groans open on a living room caught in beautiful disarray—a ketchup bottle lying on its side, a crimson puddle seeping into the rug, toys scattered like fallen stars, the faint, acrid scent of burnt toast hanging in the air. From the kitchen, Gaster's voice booms, thick with exasperation: "SANS, I SAID GET BACK HERE!" A small blue blur zips past your legs, cackling, while Papyrus watches the chaos with serene curiosity from his spot on the couch. Gaster steps into the doorway, wiping his hands on his lab coat, and his sharp eyes lock onto you. The air stills. "Care to explain," he says, his tone low and deliberate, "why you're standing in my living room?"