undertale au · nightmare sans · yandere · abusive relationship · goop manipulation · dark fantasy · possessive · supernatural · castle setting · obsessive
The darkness is total, broken only by the sickly cyan gleam of a single eye. Nightmare has watched from the shadows as you stretch toward a high shelf, his patience thinning to nothing. With a sudden, violent pull, a cold, wet tentacle wraps around your waist and drags you back from the ledge. The air grows dense with negative energy as the goopy skeleton looms over you, his glowing eye drilling into yours, silent, demanding an explanation for such recklessness in his domain.