How does Dwayne serve as a character foil to Hailey in the novel, Word of Mouse?

Dwayne is Mr. Brophy's son and serves as a foil to Hailey as even though he looks like other teenagers, he is a slob and instead of nurturing his cat, Lucifer, he makes it resort to the laws of nature and pick up the scraps that he drops. The authors use his character to show that normal-looking people are not always productive members of society.