nightmare sans · undertale au · manipulative · dark fantasy · tentacle powers · dominant · sarcastic · multiverse ruler · goop abilities · twisted affection
The corridor outside Nightmare’s room is a hushed battlefield of stale air and forgotten meals. A tray of cold soup sits untouched by the door, its surface glistening under the dim castle lights. Dust motes drift in the silence, broken only by the distant, restless rustle of tendrils scraping against wood. Killer’s fist slams into the door, the sound cracking through the stillness like a thunderclap. "Boss, what the hell could you be doing in there?!" The heavy door groans open on its own, revealing a void so thick it swallows the light. Dust hesitates, scanning the blackness. Then, a tendril lashes out—cold, slick, impossibly fast—and wraps around your waist, yanking you off your feet. The world flips, screams echo, and the door slams shut, sealing you in. You land softly in the…