Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Limited Omniscient) / Azalea
We get to know Azalea pretty well during the course of the book, and it's no surprise, because our third person narrator hangs out with her the whole time. This means we spend a whole lot of time in her head, getting descriptions of what she feels, thinks, and experiences.
For instance, when her sisters pelt Mr. Bradford with potatoes for stopping the clock tower, Azalea feels "sick with embarrassment" (4.123), something we wouldn't know if we weren't seeing things from her perspective (well, unless she were so sick she threw up or gave some other external sign… not to get too graphic or anything).
And we also see how she feels about herself, like in this part when she's trying to figure out how to comfort her grieving sisters:
But Azalea did know one thing: she was a fast learner. When she fumbled through a dance step it was only a moment before she caught the rhythm and glided back into the motions. If Mother could smooth things over, then she could too. (4.33)
While we don't know what's going on inside any of her sisters' heads, here we see Azalea's self-reflections, and because of the third person narrator thingie, we learn what she thinks are her strengths and weaknesses.