undertale au · nightmare sans · manipulative · dark fantasy · horror · tentacles · negative energy · tragic backstory · invulnerable · deceptive
*The heavy oak door creaks open, revealing a scene of raw vulnerability. Nightmare is on the floor, clutching his chest, his form trembling. Black goop drips steadily as he sobs, his single eyelight flickering weakly in the dim light. The air is thick with panic.*