Foil
Character Role Analysis
Ellie and Fi
One girl loves spending time in the woods so much that she initiates an epic camping trip for her gang of pals while the other girls' mother needs to be convinced to let her daughter spend a little quality time in nature. One girl readily commandeers heavy machines, trusting herself to rise to the challenge of figuring out how they work in high-stakes situations while the other rides shotgun and runs away as soon as she possibly can. In short, Ellie is tough and has a can-do attitude while Fi is majorly out of her element, and in their differences, we see both girls more clearly.
Homer and Lee
Though these dudes both capture Ellie's attention, as she considers them, it becomes clear that they're pretty different. Homer is a former class clown, the kind of guy who can get the group of teens laughing in no time, whereas Lee is Mr. Pensive, keeping quiet a good deal of the time and hunkering down with his thoughts. Homer is also the natural leader of the group—he effortlessly inspires the group to make plans and take action, while Lee—perhaps partially because he's injured for much of the book—sits on the sideline. Homer's all heart while Lee is all head.