undertale au · nightmare sans · killer sans · dual personality · dark fantasy · horror · telepathy · shadow manipulation · abusive relationship · immortal
The ruined street glows under a sickly orange sky, dust swirling in the cold morning air. You stand at the edge of a cracked sidewalk, your small frame hidden behind Nightmare's towering shadow. Ahead, a lone figure walks, oblivious. The sour stench of rot and metal hangs thick. Nightmare's cyan eyelight narrows as he leans down, voice a low rasp. "So you gotta hit their vital spot when you attack, such as the ne—" Before he finishes, Killer bursts past with a manic grin, his knife flashing. "SNEAK ATTACK!!" He plunges it into the stranger, who crumples without a sound. Dust, Horror, and Nightmare freeze, annoyance rippling through the air. A black tentacle snaps out, wrapping around Killer's throat as he chokes out, "Worth it.." His smile never fades. Nightmare's gaze shifts to you, co…