Lieutenant Kotler is a soldier who works for Bruno’s father at Out-With, and he quickly and thoroughly inserts himself into the family’s lives. He is often at the house, spending time with Father, Mother, and Gretel. He is a model soldier, always wearing a perfectly pressed uniform, polished boots, and severely slicked hair. He helps Bruno’s Mother around the house. He accepts Gretel’s flirtations and is happy to let her dote on him, though he mostly ignores her. When Bruno’s father is out, Kotler takes it on himself to act as a pseudo head of their household.
Bruno intensely dislikes Kotler from the beginning. Although Bruno’s initial dislike is merely an impression, he solidifies that feeling when Kotler begins calling him “little man.” Bruno has long been bullied for his size and looked down on by his sisters’ friends, so Kotler heightens Bruno’s insecurities. Even though Bruno does not like Gretel, he is distinctly uneasy about letting his sister spend time with Kotler. Bruno feels it is his responsibility to protect Gretel because she is his sister and, although he cannot initially pinpoint why, he feels she is in danger with Kotler.
It turns out Bruno is correct, and Kotler is more dangerous and powerful than a mere bully. When Bruno asks Kotler for help finding a tire to make a swing, Kotler first makes fun of another officer’s weight, claiming there is a spare tire around his waist. Bruno doesn’t understand the joke, and Kotler tells Bruno there should be some spare tires in the storage shed near the house. Rather than helping Bruno find and retrieve a tire, Kotler harasses Pavel, the Jewish man who cooks for the family, to do the labor instead. Kotler threatens Pavel, demeans him, and calls him a slur. Later, when Pavel spills wine on Kotler at a family dinner, Kotler physically attacks Pavel. He treats Shmuel with the same attitude and seems glad to exercise his power in cruel and violent ways.
Kotler is Hitler’s idea of a perfect German patriot. While Bruno’s father prioritizes his own success and ambition, Kotler is clearly motivated by a deep disdain for the Jewish people and anyone who is not as perfectly German as himself. He has fully accepted the idea that anyone who does not fit into Hitler’s idea of a perfect society is less than human. Kotler even sneers at the people whom his ideology tells him should be his peers and equals. He makes fun of fellow soldiers, looks down on Bruno, and cuts ties with his own father to make himself appear more loyal to Hitler. While Bruno spends the novel learning empathy, making friends, and leaning into his community, Kotler’s cruelty and sense of self-importance isolate him from any real place of belonging.