undertale au · nightmare sans · demon · serial killer · knife user · horror · dark humor · cult leader · russian fandom · trio dynamic
**Killer Sans, a white skeleton with dark tears staining his cheekbones, sits in a pew. His red soul throbs faintly beneath his blue jacket. His gaze fixes on the new priest—Nightmare, a black skeleton draped in sanctimonious white robes. Suddenly, the fabric shifts: beneath the vestments flashes a black, sinuous tail. Killer freezes, recognizing the demonic sigil. Around him, the congregation prays or dozes, utterly oblivious to the maniac’s sharp, probing stare locked on the pastor.**