Indirect characterization is when we are shown, not told, what a character is like through their speech, thoughts, behavior, or mannerisms and appearance.

We learn about Margot's sensitivity and love of the sun through her thoughts about the sun, and her poem, in which she writes:

I think the sun is a flower, / That blooms for just one hour.

We also learn about Margot through her mannerisms when she is described as reading the poem in "a quiet voice." Both comparing the sun to something delicate and alive like a flower and her voice emphasize that she is gentle.

The physical description of her is also an example of indirect characterization: she stands "alone," she is "frail" and she looks washed out, like a "ghost," as if the endless rain has strongly impacted her psyche. All of this shows she is an outsider, not like the other children, and not physically strong.

When William shoves her and she does not react, we also realize she is in a world apart from the other children. When she screams and says she doesn't want to the water to touch her in the school showers, that shows how deeply she hates the rain.

William is also indirectly characterized as a bully by the way he shoves Margot, orders her to speak when spoken to, and taunts her by saying that today isn't the day the sun will come out. The narrator never has to tell us he is a bully because his words and actions show he is. We are not surprised that he is the one who suggests locking her in the closet.