Leper is a peaceful, quiet, contemplative boy. He's timid – the first time we see him he's declining to jump from the suicide tree (not that we blame him). He's also a naturalist of sorts, fascinated by the outdoors. (Think about the snail collection, the beaver dam conquest, the mountain in Maine anecdote.) And Leper, like Phineas, follows his own set of rules. Look at his tirade on downhill skiing in Chapter Seven: "They're ruining skiing in this country, rope tows and chair lifts and all that stuff. You get carted up, and then you whizz down. You never get to really look at the trees, at a tree. I just like to go along and see what I'm passing and enjoy myself" (7.64). It's touching; Leper seems to remain untainted by the war, resentment and fear in which Gene has been caught up.
Which is why it's so poignant when Leper is the first to enlist. In a way, we never saw this coming (Leper? Why not Brinker?), but in another sense this is rather fitting. It shows how potent the war is, how far into Devon it can reach. No one is spared the effects of the war; no one exists outside it, even Leper.
Leper's character also serves as a constant reminder that things are changing. His leaving Devon marks the beginning of Brinker's transformation. His madness causes Finny to break with his worlds of fantasy. His psychotic visions themselves are all about the horror of transformation. Of course, this change has to do with the war, but also the process of growing up, of learning and maturing. Leper's own system of rules, his own way of thinking, is changed by the skiing video that prompts him to enter the army in the first place. He rethinks his earlier, rather adamant stance on skiing, and his new understanding of the sport is based on transformation itself. Check it out: "So I guess maybe racing skiers weren't ruining the sport after all. They were preparing it, if you see what I mean, for the future. Everything has to evolve or else it perishes. […] Skiing had to learn to move just as fast or it would have been wiped out by this war" (9.7). He adds, "You know what? I'm almost glad this war came along. It's like a test, isn't it, and only the things and the people who've been evolving the right way survive" (9.9).
This is essentially an explanation, preemptively, for Finny's eventual death. Finny doesn't evolve, so he doesn't survive. He tries to stay behind in a youthful world of sports, fun, and blissful innocence, so he perishes. Passages like this suggest that Leper has the greatest understanding of the world, the war, and the challenges which all the boys will face. After all, he is the only boy to comprehend Gene's "savage" nature.
Which brings us to an interesting question: if Leper understands everything that happened that day in the tree, why doesn't he tell the truth during Brinker's "investigation" in the assembly hall? One explanation is that Leper is just crazy. But that's too easy, and we know you don't want to settle for easy. So look at what Leper has to say for himself: "I don't intend to implicate myself. I'm no fool, you know. I'm not going to tell you everything and then have it used against me later. You always did take me for a fool, didn't you? But I'm no fool any more. I know when I have information that might be dangerous" (11.205). Leper may be fearing for Gene's well-being; after all, he earlier revealed that he considers himself Gene's best friend. But the idea of foolishness is an interesting one – what about Leper's testimony might render him a fool?
You think about that…