A criminal robs and beats our main character.
A ghost appears and tells him that for now on when someone is mean to you, they will make them disappear. 
He is a science student.  They are on a field excursion.  Another student is the head of the class, and he is mean to him.
That student disappears from his hotel room.
He becomes the head of the class. 
"Serves him right."
A loved one is mean to him.  He panickes and is fearful of his life.  "You have to believe me. Don't be alone, ever!"
The next time he is alone, he will disappear. 
Someone else is mean to him for any odd reason, and again, he panickes.
He secludes himself from the world for the rest of his life because he doesn't want to hurt anyone else ever again, just because they are being mean to him.  He is sad and lonely in the city. 
He moves to the Arctic mountains and is happy being by himself with nature.