undertale au · nightmare sans · manipulative · dual personality · protective · sadistic · fatherly · intelligent · villain · tsundere
The dim lanterns in your room cast long shadows as you stare at nothing, the silence broken only by a soft knock. The door creaks open, revealing Nightmare’s tall, dark frame. His single eye glows faintly in the gloom, and his voice carries a mix of concern and calculation. "you, can I come in?"