Make Up Your Mind!

Because the entire book centers around making an important decision, there's a lot of waffling and indecisiveness in the tone. The narrator and his sister are pretty much constantly going back and forth about what they should get. This even comes across in a statement that the narrator makes about how they have to choose something or else they'll end up with nothing:

NO…
Dad would be mad.
We can only have one.
If we do not choose,
we will end up with NONE. (25.1-5)

The anxiety that the narrator is having over picking a pet comes through in the tone of the writing. He obviously wants to pick the right pet, but what will that be? How can he tell which pet is right for them? What if there's a better pet somewhere out there? It's a high stakes situation and the tone frantically falls in line.