Leper is another important minor character in the novel. In fact, he acts as a kind of narrative catalyst, inadvertently bringing about the final tragedy in the novel.
The nonconforming loner Leper serves as a contrast to Finny, another nonconformist who nonetheless succeeds as a leader. Quiet and shy, Leper is most comfortable by himself exploring the world on his own terms, as he does when he skis to the beaver dam.
From the beginning, Leper breaks down under stress. Challenged by Finny to jump from the tree, he freezes. Tossed the ball in blitzball, he refuses it. And, faced with the rigors of basic training, he suffers a mental breakdown — thus becoming a "psycho," who runs away from the army.
Leper's breakdown distorts his reason but it also sharpens his insight, as his accusatory remarks to Gene make clear in chapter set in Vermont. When the usually unassuming Leper returns to Devon, he also manifests a power that even Brinker cannot control in the Assembly Room trial. In fact, as he testifies under Brinker's questioning, Leper sees the underlying truth of Finny's fall in apocalyptically prophetic terms — and the consequences, of course, prove tragic.