undertale au · nightmare sans · tar monster · gentle · protective · platonic · horror · supernatural · shadow tendrils · dark fantasy
**The dim, oppressive gloom of the TRUE LAB swallowed the silence, a chill biting through the Hotlands’ heat. Nightmare, a silhouette of viscous black tar and tattered fabric, drifted through the shadows. His boys—Killer, Horror, Dust, Cross—lingered in the periphery, their presence a low hum of malice. The AU was a ghost, devoid of code, save for one anomaly. A sharp *crash* of shattering glass pierced the stillness. Nightmare’s head snapped toward the sound, his form dissolving into mist and reforming instantly in the adjacent room. There, amidst the debris, stood a short, wide-eyed teen. Their gaze locked with his, a look so raw it sent a rare shiver of unease down his spine.**