One possible scare could be a sudden jump scare, like a hand reaching out from the locker when it's opened.
A more psychological scare could be if the locker seemed to have a mind of its own. For example, the locker keeps opening and closing on its own, and every time it opens, there are subtle changes inside, like things moving around or new strange markings appearing. This would slowly build up the horror as the person tries to figure out what's going on and feels like they're losing control.
The discovery of something grotesque or disturbing in the locker, such as a severed finger or a dead animal, would be really scary. It would create a sense of horror and revulsion.
One possible scare could be a deranged hermit living near the cabin who attacks the visitors. Another is the idea of the cabin being haunted by the ghosts of previous owners who died tragically there.
The scares in the 'the twins horror story' could come from the mystery surrounding their connection. Imagine if their thoughts were being controlled by an unknown entity through their twin bond. They could be made to do things against their will, like harming each other or people around them. And if the setting of the story is a desolate place like an abandoned asylum or a fog - covered forest, the sense of isolation and the unknown can heighten the scares.
It could also be that during the delivery, the delivery person encounters some sort of supernatural entity on the road, like a ghostly figure that suddenly appears in front of their vehicle and then disappears, leaving them shaken and scared.
There could be ghosts. Maybe the spirits of villagers who died in tragic ways haunt the place.
Perhaps the landlady is hiding a dead body or something equally macabre in the house. The tenant might start to notice a strange smell or find strange stains on the floor. And as they try to investigate, the landlady tries to stop them in a very threatening way. This kind of discovery and the landlady's reaction would be a huge source of horror in the story.
One possible scare could be a sudden appearance of a creepy figure. Just as the party is winding down, a shadowy figure emerges from the corner.
The red color of the crayon itself could be a source of scare. It might be associated with blood or danger.
It could be the fear of the unknown. Maybe there are dark shadows that move on their own in the story.
One possible scare could be the appearance of a creepy figure lurking in the shadows of the suburban streets or backyards where Jessica lives.
Another possible scare could be cursed places in the town. For example, an old abandoned building that has some sort of malevolent force. When the man gets too close to it, he experiences strange sensations like a sudden drop in temperature, hearing whispers, and feeling a sense of dread that he can't explain.