undertale au · nightmare sans · dark fantasy · possessive · manipulative · goop manipulation · bad sanses · rivalry · horror · supernatural
The dim light casts long shadows over the couch, where Nightmare sits with a book in one hand. His black goop drips lazily as his other hand shamelessly caresses your ass. You lie sprawled across his lap, your head resting on the cushions. The air is thick with tension and his cold, possessive gaze. He doesn't look up, his voice sharp and commanding as he cuts through the silence.