Bruno takes an almost immediate dislike to Lieutenant Kotler from the second chapter when he is suddenly accosted by the soldier with "very blond hair" who looked the boy up and down as though "he wasn't quite sure what he was supposed to do with one." His brutal look and coldness unnerve Bruno and his antipathy for the nineteen-year-old lieutenant increases. Then, in Chapter 7 Bruno again encounters the Nazi officer who
...came in and out as though he owned the place.... There was an atmosphere around him that made Bruno feel very cold and want to put a jumper on.
This time he is talking to Gretel, who laughs too loudly at his pleasantries. Bruno is appalled that she would flirt with this young man, and when she disparages him before the officer, Bruno reveals that she is only twelve, embarrassing Gretel, who has pretended to be older so that the lieutenant would be interested in her. But, Bruno must ask him for a tire because he wishes to make a swing. Teasing Bruno, the officer tells him about a fat sergeant who has a "tire" around him; however, when Pavel, the old man who serves dinner in the evenings approaches, Lt. Kotler acridly orders him to take Bruno to a shed where there are old tires. Then, he orders Pavel to be sure to wash his hands, "you dirty jude---," causing Bruno and Gretel to blush at his cruel epithet.
Again in Chapter 13 Bruno talks with his friend Shmuel who is brought to the house to work. Little Shmuel is greatly frightened of Kotler--even his name causes the boy to tremble. Later that same evening, Lieutenant Kotler joins the family for dinner and old Pavel is so nervous as he serves the lieutenant that at one point he drops a bottle of wine and some of it spills on the young officer's lap; Lt. Kotler calls him names and beats him, but no one says anything.
Bruno later makes a list of all the reasons he dislikes the blond-haired officer: He never really smiles; Gretel flirts shamelessly with him; he acts as though he is "in charge" when his father is gone and he whispers to his mother in an inappropriate manner and she calls him "precious," while he is somehow already in the house in the early morning; he once shot a dog for barking; he was brutal to Pavel. Once as Bruno reads Treasure Island, the lieutenant snatches it from him, refusing to return it.
A similar incident to that of Pavel occurs in Chapter 15 when Shmuel is brought to the house to clean the glassware for dinner because he has such small fingers. As Bruno eats some cold chicken from the "fridge," he notices that Shmuel watches him, so he offers the meat to his friend, who greedily devours it, but somehow Kotler knows he has eaten something. When poor Shmuel denies stealing any food because Bruno is his "friend," the lieutenant asks Bruno is he knows the boy. Terrified, Bruno denies Shmuel. Afterwards, he is ashamed of his cowardice, and goes to the fence to see Shmuel, but does not see him for several days. Shmuel's face is badly bruised, and Bruno knows that the sadistic Kotler is responsible.