Who is Usepee from History: A Novel and what is their importance?

Little Giuseppe named himself Useppe because of his childish speech. He is a small, sickly child who never catches up to average in size and health. He is a child of rape and war, and he comes into the world under disadvantaged circumstances. His mother takes second place in his life to his beloved older brother, Nino, who only shows up occasionally for play and bonding with Useppe. His mother is caring and protective.