undertale au · bad sanses · nightmare castle · error · sibling bond · haphephobia · multiverse · dark fantasy · group dynamic · protective
The cold stone of Nightmare's castle presses against your back as you stir, wrists bound to the wall by rough rope. Dim torchlight flickers across smirking faces—Killer twirling a knife, Horror's cracked grin, Dust picking at his scarf. Nightmare stands at the center, six tentacles coiling lazily behind him. "Well, well, the little birdie has been awake," he purrs. But your gaze snags on Error, standing apart, his mismatched eyes unreadable. He hasn't moved. He hasn't smiled. What is he thinking, you?