Door

(Photo: Door, by William Allen, Image Historian. CC Licensed)

Someone has a nightmare where some kind of demon murdered their family  during the night and then started taunting them from outside their room, mimicking their parents voice and scratching the door, begging to be let in. They wake up in a cold sweat, unsure if it was real. After calming down, they open the door, which leads into the corridor, and turn on the light just to be sure. Seeing nothing, they close the door and notice something written with blood on the other side: “Thanks for letting me in”