A Slender Whistle of Air

My paws drifted across the cool floorboards until a sudden breath of warmth tickled my whiskers. Near the metal floor register, a stray brown envelope lay slightly curled at the corner. I paused three measured breaths away, listening to the soft flutter whenever the furnace hummed below. Creeping close, I pressed one soft paw against the stiff paper rim. It flattened with a crisp, dry rustle against the iron grate, letting a thin stripe of morning sun catch the faint crease before resting still.