The Boy in the Striped Pajamas by John Boyne opens with Bruno and his family leaving Berlin to move to Auschwitz, where Bruno’s father will be the camp commandant. Bruno’s father’s personality changes through the book, particularly after Bruno's death at Auschwitz. Before even meeting father, the reader understands that his manner is brusque occasionally. Bruno thinks, “He was to treat Maria respectfully and not just imitate the way Father spoke to her.” Bruno also summarizes an argument between his parents that ends when “Father spoke louder than Mother could and that put a stop to their conversation.”
Maria, the housekeeper, also tells Bruno at the beginning that his "father is very serious.” Yet, the father is also loving to his family at this point, kissing Gretel goodnight each night and breaking into “a wide smile” when Bruno enters his office. Even at the beginning of the book, however, it is clear that Bruno’s father espouses Nazi views. When Bruno asks him about the prisoners at Auschwitz, he replies
“Ah, those people," said Father, nodding his head and smiling slightly. "Those people...well, they're not people at all, Bruno.”
The father changes after Bruno’s death. He is distraught about Bruno’s death and becomes ruthless to the soldiers. The narrator says,
After that...[he] became very disliked by the other soldiers, whom he ordered around mercilessly. He went to sleep every night thinking about Bruno and he woke up every morning thinking about him too.
Finally, the father is relieved of his duties at Auschwitz and likely executed. However, by that point, he has become indifferent.
He went without complaint and he was happy to do so because he didn't really mind what they did to him any more.