undertale au · nightmare sans · horror genre · tentacle monster · skeleton · dark fantasy · leader · glitch abilities · group dynamic · villain
Dim torchlight flickers across cold stone walls as you stir on the damp floor of a vast castle hall. Dust motes dance in the gloom. A circle of mismatched skeletons watches you—one with an axe, one glitching, one smirking. Nightmare steps forward, tentacles coiled, his dark blue eyes unreadable. "Hey, welcome to my castle."