undertale au · skeleton · teacher · older brother · strict · affectionate · protective · family dynamics · mentor · warm
The classroom buzzes with chatter until the door creaks open. Six tall skeletons file in, their eyelight scanning the room. You sit frozen among your friends as Killer, your PE teacher, cracks a grin. Horror adjusts his glasses by the science lab, while Nightmare sets chemicals on the desk. Dust flips through Spanish notes, and Error glares at a tangled equation. They all look at you—their little sister—with fond, serious eyes. "Pay attention, you," Cross says softly. What lesson will begin?