The suspense. In a short story, there's not much room for long - winded build - up. So, every word counts towards creating that sense of unease and anticipation. For example, in 'The Lottery' by Shirley Jackson, the reader is kept in the dark about the true nature of the lottery until the very end, creating great suspense.
One insanely scary short story is 'The Tell - Tale Heart' by Edgar Allan Poe. It's about a narrator who is driven mad by an old man's 'vulture - like' eye and eventually murders him. The guilt then drives the narrator to confess.
One insanely scary story is about a haunted house. People who entered it at night heard strange whispers and saw shadowy figures moving in the corners. There were cold spots throughout the house, and doors would slam shut on their own. Once, a family moved in, and their young daughter started talking to an 'invisible friend' who would ask her to do dangerous things.
One insanely scary ghost story is about the old abandoned asylum. People say that at night, you can hear the screams of the patients who once suffered there. Lights flicker in the empty hallways, and the figure of a nurse in a blood - stained uniform has been seen pushing a gurney with no one on it.
The sense of helplessness also contributes to the terror. In many scary stories, the characters are unable to escape the situation they're in. Like in a story of a person trapped in a cursed house, they try everything but can't get away, and this feeling of being powerless is very frightening. Additionally, the use of dark and eerie settings, such as a desolate cemetery or an abandoned building, adds to the overall scariness as these are places that are often associated with danger and the supernatural in our minds.
The unknown aspect makes insanely scary ghost stories terrifying. We don't know what ghosts are really like or what they can do. For example, in a story where a ghost haunts a house, we don't know when it will appear or what it will do when it does.
Perhaps a story of a man who bought an old antique mirror. Every time he looked into it, he saw a figure that wasn't his reflection. The figure seemed to be getting closer and closer each time. One day, he woke up to find the figure standing at the foot of his bed.
One insanely smart Naruto fanfiction could be one that delves deep into the political intrigue of the Hidden Villages. It might show Naruto using his smarts to outwit the elders and bring about real change. For example, a story where he uses his knowledge of history and the weaknesses in the village's power structure to prevent a civil war.
The element of the unknown. For example, in many of the stories, there are unexplained noises or figures. We don't know what they are or what they want, and that scares us.
One idea could be a story about a haunted mirror. A young girl moves into an old house and discovers a large, ornate mirror in the attic. Every time she looks into it, she sees a figure that gets closer and closer each day. Eventually, the figure steps out of the mirror.