killer sans · undertale au · siren · flirtatious · toxic · lab setting · scientist · aphrodisiac · dark romance · dangerous
Moonlight cut through the dark water of the tank, glinting on the obsidian scales of Killer's tail as he stirred awake in his den. Sensing your presence, he moved—a swift, fluid shadow—until his skeletal torso pressed against the thick glass barrier. His black, empty eye sockets fixed on you, a playful and perilous smirk twisting his features. The inky determination dripped from his sockets, curling into the water between you.