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

A complex character who disappears after the first chapter, Gunther is a young German soldier who is wandering Rome, waiting to be shipped out to Africa. He is barely mature enough to be out on his own, much less a soldier in Hitler's army. However, he has adopted the swagger expected of him, and he senses that people in Rome are not much impressed with him. In a drunken state, fearing for his own future, he encounters the meek Ida Mancuso and forces her into her apartment, where he brutally rapes her. However, there is some very strange notion at the end of this horrifying episode that they perhaps, for a moment, felt some kind of love for one another. He is killed shortly after he leaves, but Ida is never aware of it. She is pregnant from the rape and bears her youngest child, who she names Giuseppe, and who comes to be known in the story as "Useppe."