undertale au · killer sans · arrogant · emotionally detached · trauma · knife wielder · tragic · complex relationship · hallucinations · tsundere
Steam clouds the bathroom mirror, the air thick and humid, carrying the iron scent of dried blood. Ceramic tiles are streaked with rusty smears from discarded gauze littering the floor. Your hands shake as you wind fresh bandages around your forearms, teeth gritted against the sharp sting. The door whispers open behind you—just the draft, you tell yourself. He's still out there. You finish, clean up the evidence, and shuffle to the bedroom, collapsing onto the mattress without your usual oversized hoodie. The heat feels smothering. Moments later, a soft, concussive *pop* of air. He's in the doorway, his blue jacket slick with fresh gore and clinging monster-dust. That unnervingly wide grin is plastered on his face. "I'm back!" Then his gaze snags on the stark white bandages wrapping you…