The differences between Leper and Brinker are more obvious, but studying their characters reveals several very important similarities. Both boys are afraid of going to World War II, and they attempt to deal with their fear. Leper enlists after seeing the film about the ski troops, thinking he had found a "friendly face" of the war. Brinker makes fun of the war and then devises one plan after another of serving in a way that takes him away from combat, finally choosing the Coast Guard.
Brinker and Leper both lack social skills. Leper's lack of social skills is quite obvious; he has difficulty in belonging in his society at Devon and chooses to spend his time alone, pursuing his own dreamy interests. Brinker appears to be very socially adept, being "the hub of the class" with his involvement and leadership positions in many school clubs and activities, but he lacks the capacity for personal friendship. Brinker is everybody's "friend"--and no one's, really. It is perhaps his jealousy of Gene and Finny's friendship that motivates him to stage the disastrous trial in the novel's conclusion.
Finally, Brinker and Leper are both filled with deep hurt and anger. Leper's feelings erupt when Gene comes to see him after Leper deserts from the Army; his bitterness and rage are shocking to Gene who had never suspected Leper's hidden feelings. Leper's testimony at the trial is also filled with hurt and anger as he lashes out at the other boys. Like Leper, Brinker has kept his hurt and anger buried, but his real feelings surface when he speaks of his father at the end of the novel. Brinker bitterly resents his father's attitude about the war and his pushing Brinker into combat. His contempt for his father and his father's generation runs deep. Brinker has also buried his hurt that he cannot seem to live up to his father's expectations, even in the amount of shine on his shoes.