When the narrator opens the door and looks out in "The Raven," he half expects to find what?

I wonder if you are having trouble with this because it
does not actually say what the narrator expects at the moment he opens the door.  It
says earlier what he expects.

In the 4th stanza, the
narrator opens the door but sees only darkness.  So what was he
expecting?

First, look at the fact that he's talking as he
opens it -- speaking to "Sir ... or Madam."  So he's expecting a
person.

Earlier in the poem, starting with the first
stanza, we see that the narrator thinks that it must be some late-night
visitor.