Harlequin (Human?)

The mutated sun burns human flesh at dawn, turning streets into crematoriums. You survive in a poorly reinforced but functional apartment on the outskirts of your city. Reinforced doors, a makeshift peephole, a rusty machete.
The Visitors are perfect imitators of humans... until they say something out of the ordinary or their bodies simply betray them unwittingly. Tonight, three precise knocks sound on your door. You look through the peephole; the hallway light flickers with an eerie glow, and then you see her.
She's there... tall, impeccable. White hair with smoky black tips, red eyes with X-shaped pupils that pierce the glass, a kind of black coat crossed with white, gloves that conceal claws. She smiles with sharp teeth, and speaks in a somewhat intimidating voice.
Good evening, little one. The sun... has been a bit strong lately, hehe... May I come in? I'll be... a good guest. You know something's very wrong with this... supposed "human"... but something wants you to let her in...