The rain continues on and off for the next few weeks, during which Bruno is unable to meet with Shmuel as often as he would like. When he does see Shmuel, he notices that he is getting even thinner and more sickly looking, so Bruno tries to remember to bring him more food. Meanwhile, Mother is planning a birthday party for Father and Lieutenant Kotler is spending a lot of time at the house with her. This makes Bruno uncomfortable and he dislikes the young soldier even more that he already had, especially since Lieutenant Kotler is always joking with Mother and "Mother [laughs] at his jokes more than she [laughs] at Father's" (162).
On the day before Father's birthday party, Bruno runs into Lieutenant Kotler in the hallway and the soldier grabs Bruno's book, Treasure Island, from his hands. He taunts Bruno a bit before Mother enters, calling Lieutenant Kotler, "Kurt, precious" before realizing that Bruno is there (165). She sends Bruno into the kitchen, where he is surprised to find Shmuel sitting at the table. Lieutenant Kotler has brought him there because his hands are small enough to polish the glasses for Father's birthday party. Bruno begins to help himself to some cold chicken and stuffing that's in the refrigerator and when he sees Shmuel looking at the food, he offers his friend some. Shmuel is hesitant because he knows he'll get in trouble if Lieutenant Kotler returns, but Bruno puts the food in his hands and he scarfs it down.
Lieutenant Kotler returns and scolds Shmuel for not polishing the glasses. When he accuses Shmuel of stealing food to eat, Shmuel tells him that Bruno gave it to him, and that Bruno is his friend. But when Lieutenant Kotler asks Bruno if he knows the boy, Bruno denies it. Lieutenant Kotler tells Shmuel to finish polishing the glasses, and that when he brings him back to the camp, they "will have a discussion about what happens to boys who steal" (173). When Lieutenant Kotler tells Bruno to go read his book, Bruno obeys and leaves the kitchen, feeling incredibly guilty about having betrayed his friend.
For almost a week, Shmuel does not come back to meet him at the fence. When his friend finally returns, his face is covered in bruises. When Bruno asks about his injuries, Shmuel says it doesn't hurt anymore. Bruno apologizes for letting him down and says he's ashamed of himself. Shmuel smiles and forgives him, lifting up the fence so that they can shake hands beneath it. It is the first time the two boys have ever touched.
At this point, almost a year has passed since Bruno and his family left Berlin to come to Out-With. The family receives news that Grandmother has died, so they return to their old home in Berlin for two days to attend the funeral. The two days are so sad that Bruno is almost relieved to return to Out-With. In fact, he muses that things are pretty positive at his new home recently: Mother is no longer taking as many "afternoon naps or medicinal sherries" (178) and Gretel is staying out of Bruno's way for the most part. Additionally, Lieutenant Kotler has been suddenly transferred away from Out-With, coinciding with a huge fight between Mother and Father. Mostly, Bruno is happy because his friendship with Shmuel has become even stronger.
Bruno has begun to wonder more and more about why he and Shmuel are living on opposite sides of the fence, so he decides to ask Gretel about it. She has thrown away all of her dolls and replaced them with maps of Europe. When he asks her about the fence, she first corrects him on his pronunciation of "Out-With." Then she explains that the people on the other side of the fence are Jews and that the fence is there to keep them from getting out and mixing with anyone else. When Bruno asks her what he and their family are, if not Jews, she says simply that they are "the opposite" (183).
While they are talking, Gretel notices something in her hair and begins screaming. Mother arrives and finds that both Gretel and Bruno have lice. They treat their hair with a special shampoo, but then Father goes a step further and insists that Bruno have all his hair shaved off. Father shaves it off himself. When Bruno looks at himself in the mirror, he feels sick, but thinks that now he looks even more like Shmuel. When they see each other the next day, Shmuel laughs at Bruno.
For the next few weeks, Mother becomes more and more unhappy. Bruno overhears her speaking with Father in the office one day and learns that she wants to return to Berlin with Bruno and Gretel, leaving Father to work at Out-With by himself. Mother begins napping even more and having even more medicinal sherries, causing Bruno to worry about her health. Then Father calls Gretel and Bruno into his office and asks them if they miss Berlin. Gretel confirms that she does, but Bruno is hesitant because he knows he would miss Shmuel if they left. Father tells them that the Fury will not relieve him of his command, but that Mother wants to go back to Berlin immediately.
Father remarks that perhaps she is right that Out-With is "not a place for children" (191). Bruno pipes up that there are hundreds of children there, but they are living on the other side of the fence. Father is surprised that Bruno has noticed them, but this information seems to help him make the final decision that the children should return to Berlin with Mother. Preparations begin so that Mother, Gretel, and Bruno can return to Berlin that week, but Bruno is nervous about telling Shmuel the news.
The limitations of the third-person narrator are apparent in describing the relationship between Lieutenant Kotler and Mother. Bruno is made uncomfortable by it, but he doesn't understand the extent of it. All he knows is that "whenever Father was called away to Berlin on an overnight trip the lieutenant hung around the house as if he were in charge: he would be there when Bruno was going to bed and be back again in the morning before he even woke up" (163). The reader is meant to understand that Mother and Lieutenant Kotler are having an affair, but that possibility doesn't even cross Bruno's mind. When Lieutenant Kotler is suddenly transferred away from Out-With in Chapter Sixteen, Bruno notes that "there had been a lot of shouting between Father and Mother about it late at night," but it doesn't occur to him that Father has discovered Mother's affair with the young soldier and sent Lieutenant Kotler away as a result (178).
Gretel's character develops further in Chapter Sixteen, and now she has firmly arrived on the other side of childhood. She has replaced her collection of dolls with maps of Europe given to her by Father, which she updates using the newspapers each day as she reads about developments in the war. Her transition out of childhood naivete is represented clearly in her correction of Bruno's mispronunciation of "Out-With." It was she who first told him the name of the place, but now she corrects him. When he asks her about the fence, she explains to him that their family is "the opposite" of the Jews on the other side of the fence (183). Her understanding of the situation is still simplistic and lacks understanding: she has accepted what her Father and Herr Liszt have taught her without much critical thinking.
The theme of the natural versus the unnatural emerges again in Chapter Fifteen, in the metaphor used to describe the differences between Bruno's and Shmuel's hands: "[although] Bruno was small for his age, and certainly not fat, his hand appeared healthy and full of life. The veins weren't visible through the skin, the fingers weren't little more than dying twigs" (168). Shmuel's living situation at Out-With is unnatural and thus, like a withering tree, he is slowly dying. The difference in the boys' hands is presented as a physical representation of just how different their life experiences are at Out-With. Shmuel tells Bruno that "[everyone] on my side of the fence looks like this now" (168).
Bruno's betrayal of Shmuel in front of Lieutenant Kotler is representative of the many people who betrayed their Jewish neighbors and friends during the Holocaust in similar ways. By distancing himself from Shmuel because he is afraid of the consequences of associating with the boy, Bruno contributes to Shmuel's punishment for a crime he did not commit: stealing food. The way Bruno considers his actions immediately following the event reflects a personal disconnect: "[he] wondered how a boy who thought he was a good person really could act in such a cowardly way toward a friend" (174). He feels ashamed of himself, but does not take action to right the wrong. When Shmuel finally returns to meet him at the fence, his face covered in bruises, Bruno apologizes. His words could have easily come from any of the Germans who fell in line with the Nazis and didn't speak up for the Jews during the Holocaust.
Certain events in Chapters Fifteen and Sixteen foreshadow the tragic conclusion of the story. First, Shmuel lifts up the fence that separates the two boys so that they can shake hands beneath it. It is the first time they have touched, and it foreshadows the moment when Bruno will crawl under the fence to help Shmuel look for his father. In Chapter Sixteen, after discovering that he and Gretel both have lice, Bruno must have all his hair shaved off. He and Shmuel both think it makes them look even more alike. Significantly, it is Father who shaves all of Bruno's hair off, inadvertently making it possible for his son to be confused for a Jew when he crosses under the fence.
When Bruno overhears Mother confronting Father in Chapter Seventeen, the reader learns more about the power dynamic between his parents. In the previous chapter when her children got lice, Mother complained, "If some people could only see the effect this place is having on us all" (185). She had been passive-aggressively referring to Father, just as she always has throughout the story. But in Chapter Seventeen, she speaks up for herself and demands to leave Out-With. She tells Father, "This is your assignment, not ours. You stay if you want to" (187). At a time when gender roles determined that a wife obey her husband, this distinction between his responsibilities and her own is a bold statement.