Fear is the central theme of "The Red Room." The narrator of the story challenges himself to spend a night in a supposedly haunted room. Everyone else is terrified of the red room, but he confidently announces that he will prove that the room isn't haunted. He himself doesn’t believe in anything supernatural, and is certain that his reason and good sense will conquer whatever irrational fears he might have. However, his fear turns out to be much stronger than he originally realizes: it can't be controlled by his intellect. As the story progresses, the narrator’s fear gets stronger until it completely overwhelms his self-control. Fear is clearly the antagonist of the story. At the end, fear is revealed as a dangerous force, akin to an evil spirit, which counts among the greatest enemies of any human being.
The narrator’s fear is both in his head and in the room itself, because it is the rooms' suggestiveness that creates his fear.
The main source of the narrator’s fear is his overactive imagination.