Quote 1
In the silences between jokes about Leper's glories we wondered whether we ourselves would measure up to the humblest minimum standard of the army. I did not know everything there was to know about myself, and knew that I did not know it; I wondered in the silences between jokes about Leper whether the still hidden parts of myself might contain the Sad Sack, the outcast, or the coward. We were all at our funniest about Leper, and we all secretly hoped that Leper, that incompetent, was as heroic as we said (9.16).
Leper becomes a reflection of all the boys' dreams of their own future selves in the army. What does it say, then, that Leper goes mad and abandons ship?
Quote 2
"That was when things began to change. One day I couldn't make out what was happening to the corporal's face. It kept changing into faces I knew from somewhere else, and then I began to think he looked like me…" (10.77).
Leper's visions betray a fear of changing identity – think about this in the context of what's going on between Finny and Gene, as the latter "become[s] a part of" the former.