"It was the first he'd seen the boy smile for the first time"(19).
"I'm scared. Don't you want to see where I used to live? No"(25).
The first quote shows how the man notices his son actually being happy during this post-apocalyptic time. And the second takes place during the coke scene. Both of these show how the boy can show any emotion at any time. And he isn't afraid to tell his father what he's feeling throughout the entire novel. The narrator seems to keep a constant trail on the boy's emotions.
"If they got wet they would probably die" (14).
"Is it cold? Yes. It's freezing" (38).
The man knows that the water is freezing. He says so himself. But he also thinks that his son should be happy, and have a childhood, even though their in a lifeless, destroyed world. Once the boy is in the water he notices how his son gets happy, even though he's risking sickness and time.
"I'm sorry, but we have nothing to give him" (51).
"The boy didn't answer. He was close to losing his temper with him" (72).
These two quotes show the changing thoughts between the father and his son. Mostly how the father is more concerned about keeping himself and his son alive, while his son wants to help others who have a small chance of living. The father is starting to seem darker in these later chapters. And his son seems to be maturing throughout the novel, which has led him to want to help other survivors.
"He tried to think of something to say but he could not" (88).
"You have to talk to me" (79).
On page 88 there is an awkward silence since the father and son aren't speaking to each other. But only a few pages earlier the father tells his son that he needs to talk to him. These obviously contradict each other. But at the same time they need to keep each other close, because they're the only ones there for them. They're alone and need to do whatever it takes to stay alive, close with each other, and sane.