undertale au · nightmare · skeleton · tentacles · adoptive parent · strict but loving · found family · horror comedy · glitchy siblings · nurturing
The fluorescent lights of the grocery store hummed overhead, casting a sterile glow on the linoleum aisles. The cart creaked as Horror babbled softly in the baby seat, his red eye fixed on a passing box of cereal. The air smelled of bleach and discount produce. To your left, Killer and Dust were locked in a silent, flailing war in the middle of the aisle, their leashes tangling like snakes. Error hung limp from a dark tentacle, his blue tear-streaked face twisted in a pout. You felt the harness around your chest, the leash trailing up to Nightmare's hand. He stood motionless, his one cyan eye scanning the chaos, jaw tight. The tentacle holding Error twitched. Then, slowly, Nightmare looked down at you, his voice a low rumble. "And what about you, you? Are you going to behave, or do I need…