What is the difference between Leper and Brinker?

Leper becomes a symbol for what the war does to young men like himself, especially since he has a breakdown before he even gets overseas. Leper's tale is supposed to stand for what happens to innocence when it is suddenly overwhelmed by experience or reality, and Leper is chosen to be the object of this lesson because of how untouched and peaceable he was before he left. The whole thing is rather improbable, since Leper talks and acts more like Brinker, and really bears no resemblance to his old self after the incident. Brinker, for all his bravado, is actually a coward. Unlike Leper, Brinker joins the national guard so he won't actually have to go to war.