As it turned out, Cory Cormier had always wanted a little sister, and we had one to spare.”
-- Caleb (chapter 1)

Importance: Cory is auctioning off his bag of fireworks, and he trades the bag to Caleb and Bobby Gene in exchange for their little sister, Susie. This quote is the final sentence of Chapter 1, and it is meant to pique the reader's interest.

It was easy to believe everything Styx promised, until you started trying to think it through.”
-- Caleb (chapter 8)

Importance: Caleb and Bobby Gene are talking to Styx for the first time after making the deal with Cory, and Caleb hates that Bobby Gene's questions make him skeptical that Styx can produce the deal he has promised. This skepticism is evidence of Caleb's intelligence, but his willingness to believe in Styx is evidence that he wants something extraordinary to happen. The fact that Bobby Gene's words have an effect is evidence of the relationship...