[2] Peter constitutes the first time in the Oz series in which a boy from the United States serves as the protagonist in the novels, rather than a supporting character.

[5] His travels to the world of Oz provide him opportunities to display courage, independence, loyalty and other traditional virtues; in this, he differs from Button-Bright and Bob Up, younger children with less effect on their plots.

At the end of Gnome King, Peter has a chance to become a prince of Oz — which he rejects, out of loyalty to his friends and fellow baseball-team members at home in Philadelphia.

His attitude toward life is somewhat insouciant and devil-may-care; in the opening chapter of Jack Pumpkinhead he wonders idly if "the Gnome King has gotten into any more mischief" — giving little serious consideration to the most persistent villain in the Oz universe.

Thompson herself noted her tendency to favor boy heroes,[6] in contrast to Baum's preference for girl protagonists (Dorothy Gale, Princess Ozma, Betsy Bobbin, and Trot).