"The Raven" is about a man who is grieving over the death of his lost lover, Lenore, and how he plunges deeper and deeper into depression. Poe uses suspense to help readers empathize with the man's feelings even as they hope he will find some relief from his despair. Poe builds the suspense through repetition, dialogue, and descriptions of the man's thoughts.
First, the repetition at the end of six of the first seven stanzas of the words "nothing more" gradually builds suspense, convincing readers there must be something more. The repeated words "Lenore" in stanza 2 and again in stanza 4, as a question, build the suspense that the something more might be an apparition of Lenore herself. When the final word of each stanza changes to "Nevermore" for the last eleven stanzas, suspense builds again. Readers wonder how long this can go on. Surely the refrain will change to something more positive in the next stanza!
The dialogue also contributes to the suspense of the story. When the man begins speaking to the raven, readers also are carried along by the mystery of this "ungainly fowl," wanting more information about its origin and purpose. Readers soon come to understand, as the narrator has suggested, that this one word "is its only stock and store," and they remain in suspense wondering when the man will catch on and stop expecting the bird to say something else.
Finally, Poe gives readers glimpses into the psyche of the narrator to increase the poem's suspense. He begins in sorrow, and soon the rustling of his curtains "filled me with fantastic terrors never felt before." This reference to "terrors" so early in the poem builds suspense in readers. Why should the man be in such a fragile state of mind? After speaking with the raven, the man starts "linking fancy unto fancy" and "guessing," feeling the raven's eyes burning into his "bosom's core." Readers perceive he is losing his grip on reality and wonder where that will lead. Sure enough, the narrator then imagines he smells Lenore and hears her footsteps, and the suspense from the earlier expectation of an apparition builds. As the story nears its climax, the man asks the wrong question of the raven — one he should have known the raven had to answer in only one way. The man's rants against the bird, which has now become not a real bird but a "devil" and "thing of evil," are powerless to lift him from "out that shadow that lies floating on the floor." The narrator has completely succumbed to depression.
The suspense Poe creates through repetition, dialogue, and descriptions of the man's mental state help readers understand the downward spiral into depression to which a grieving person's perseverating thoughts can lead.