Stones in Water is a 1997 young-adult novel by Donna Jo Napoli about a pair of young boys in Venice who are captured by Nazis and sent to a work camp.
A good example of the Man vs. Man conflict type occurs right in the beginning of the novel; Roberto wants to go see a Western film and promises a midnight gondola ride to an older boy, Memo, in exchange for tickets. When he returns home to get his shoes, his older brother Sergio grabs his arm and questions him:
"Just where do you think you're going?"
"What's in Mestre?"
"I know about films. Films don't start until the afternoon."
"We're walking. It'll take us that long just to get there."
On finding out that Memo is paying, Sergio comes with Roberto:
Roberto twisted his mouth in worry. He didn't want Sergio coming along, bossing him around. "Where'd you get the money?"
"Memo will pay for me, too."
"You'll do him the favour twice."
"That's not fair."
"That's what big brothers are for: to teach you the facts of life. Fact number one: life isn't fair."
(Napoli, Stones in Water, Google Books)
Roberto and Sergio have a conflict; Roberto wants to go alone, Sergio wants to go with him. Because of Sergio's older status, he is able to impress his will on Roberto, who is unable to argue. This conflict leads directly into their capture and internment, starting the plot of the novel. Because of Sergio's insistence on accompanying Roberto, he too is sent to a work camp.