What are some signs that the relationship between bruno's mom and lieutenant tler has developed?

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.