As you know there were "groups" the people in camp were divided into - Germans, the Kapos and the Jews. What parts did they play inside that camp?
The stratification that is presented helps to bring to light the idea that torture and cruelty is something that was not limited simply to the Nazis. Rather, one of the most brutal experiences of the Holocaust was that the entire structure of existence was predicated upon pain and brutality. The Kapos were representations of this idea, someone whose job became to instill order at all costs, or to subject the victims to the Holocaust to even more degradation and brutality. In this light, the entire "social" configuration of the Holocaust world was one in which brutality and a lack of dignity permeated through consciousness and being in this world. I think that the German Nazis started this process, representing the highest order in society, and from this, the secondary and tertiary levels, such as the Kapos, emulated what was being practiced at from the top down. In this light, Wiesel seems to be suggesting that when a social order is complicit in the degradation and indifference towards individual suffering, bad things will always result. The emulation of power was seen when the prisoners start to silence one another, almost doing the work of the Kapos, and by extension the Nazis, for them. In this light, one of the overriding themes becomes how the cruelty and indifference of human beings becomes so easy to duplicate.