Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Limited Omniscient)
Let's talk about our new best friend, the narrator in O Pioneers!
This narrator really gives us the inside scoop on the novel's characters. In fact, most of what we know about Alexandra's character is based on this type of direct characterization. Take, for instance, the description of her feelings and desires as an "underground river" (3.2.1). (Check out her "Character Analysis" for more.) That's just the kind of thing we wouldn't know if the narrator wasn't there to provide this metaphorical description.
But hold on a sec. In the example above, the narrator is telling us that there are parts of Alexandra that remain hidden from view. And that includes from our view. We aren't exactly privy to the contents of Alexandra's "underground river." What gives? Why you holding out on us, narrator?
In this and other instances, the narrator delves into the psyches of certain characters, without, however, spilling all the beans. We call that limited omniscient—the narrator knows a lot about the characters, maybe more than they know about themselves, but there also appear to be limits to this knowledge.
By limiting our access to the novel's main character the narrator does more than just come out and tell us about her "hidden" personal life. By the use of narrative techniques, the narrator actually helps to hide this personal life. In this way, the novel's narrative technique is in cahoots with the narrator's portrayal of Alexandra; we're led to believe Alexandra must be the way she's described, because that's also the way she's being narrated.