The relationship between both characters is not exactly a good one. Bruno sees Lt. Kotler as arrogant, walking around "as if he owned the place" and seeing him as an external force in his home. As Bruno is attempting to adjust to life in Auschwitz, Lt. Kotler's frank sense of entitlement and power is something that Bruno cannot fully appropriate or accept. As his father is gone for most of the day, Lt. Kotler "whispers" to Bruno's mother and becomes the object of his sister's desire. These realities help to foster a sense of resentment and antagonism towards Lt. Kotler. Interestingly enough, Bruno's antipathy towards him helps to spawn his widening of compassion and awareness of the world in which Bruno lives. Consider in Chapter 7, the incident between Bruno and Lt. Kotler over a spare tire is what enables Bruno to learn of Pavel and the life he led before the life he leads in Auschwitz. Consider in Chapter 9, as Bruno becomes more used to his life at the camp, that he begins to wonder about the groupings of people at the camp. It seems that as Bruno's rejection of Lt. Kotler becomes more pronounced and defined, he becomes more interested in what Lt. Kotler stands against. It seems that as their relationship becomes one of antipathy, Bruno's relationship to the "other" becomes stronger.
I think that lt kotlers relaishionship with Bruno is not that good since he is often seen with mother and it seems that there is something happening between them as well as gretel so it's like he's playing a two man game with them and thet he always acts like the boss whenever father is not there and that he is very cruel like the time when he shot a Dog that had only been barking at the fence and hadn't done anything at all. He is a devout nazi as well. Father thinks his father is a traitor.