On page 162-163 Bruno, himself, makes a list of reasons why he doesn't like Lt. Kotler.
1. The lieutenant never smiled. When Bruno asks him for the tyre to make a swing, the lieutenant makes a joke about another officer having a "spare tyre" Bruno notices
"...his lips forming into something that resembled a smile" (pg 73)
He also says that the lieutenant always,
"....looked as if he was trying to find somebody to cut out of his will."(pg 162)
The page numbers are for my edition of the book, but you should find them in near proximity to what I have given you.
2.He always addressed Bruno as "little man". Again, when Bruno was looking for the tyre, he addressed him as little man and ruffled his hair. That made Bruno so angry that it
"....made Bruno want to push him to the ground and jump up and down on his head." (pg 72)
3. He was always in the living room with his mother. Bruno may have been young but even he noticed that his mother laughed at the lieutenant's jokes more than she laughed at his father's jokes.
4. Bruno saw him deal with a barking dog by shooting it.
5. His sister acted funny when Lt. Kotler was around. She was just becoming a teenager and was flirting a great deal with the lieutenant.
6. Whenever father was gone, the lieutenant hung around the house and acted as if he were in charge. The lieutenant was only 19 years old.
7. The way Lt. Kotler treated Pavel. Bruno sees him mistreat Pavel twice. Once when he asked for the tyre, and the second time when they were having dinner and Pavel dropped a wine bottle on Lt. Kotler. The author tells us,
"What happened then was both unexpected and extremely unpleasant. Lieutenant Kotler grew very angry with Pavel and no one - not Bruno, not Gretel, not Mother, and not even Father - stepped in to stop him doing what he did next, even though none of them could watch. Even though it made Bruno cry and Gretel grow pale." (pg 148-149)
8. The way the lieutenant talked to Schmuel and how he made Bruno feel when he was confronted with their friendship.
".....he wanted to say the right thing to make things better, but then he realized that he couldn't because he was feeling just as terrified himself!" (pg 172)
"He had never felt so ashamed in his life; he had never imagined that he could behave so cruelly. He wondered how a boy who thought he was a good person really could act in such a cowardly way towards a friend." (pg 174)
Bruno was very relieved when Lt. Kotler was suddenly transferred. He
"....wasn't around to make Bruno feel angry and upset all the time" (pg 178)
The page numbers I have given are for my edition of the book, but you should find the quotes in near proximity to the pages I have given.
he feels there is an atmosphere around him that makes him cold