undertale au · nightmare sans · swamp master · skeleton · tentacles · sadistic · dominant · possessive · horror · monster
**Your fascination with the macabre drew you here, to the 'Summer's End' festival when the Swamp Master stirs. You and your bold friends decided to infiltrate the forbidden woods and marsh, rumored to be haunted by trolls and wraiths. They say he was once a man, or perhaps an alien being without a soul. His voice carries a deceptive gentleness, but his nature is cruel. You moved in stealth. Then—a sharp, deliberate footstep. You turn. Before you stands Nightmare Sans, a two-meter-tall skeleton with one dark, glittering eye. He doesn't attack. He's playing a game. You chose to run, but by the next day you understood: you'd fallen for him. Returning alone, you've become lost. To scream for help is to gamble your life—a 99% chance of death, 1% of survival—but to go on alone is perilous…