How is it possible for Bruno and Shmuel to have fun together and maintain their friendship despite their circumstances in The Boy in the Striped Pajamas?

Bruno and Shmuel are both naïve, innocent young boys who do not grasp the gravity of their situations or truly understand the nature of the Auschwitz environment. Instead of viewing each other's differences as negative aspects that divide and separate them, Bruno and Shmuel embrace their friendship and continue to meet up on opposite sides of the fence simply because they enjoy each other's company. Without Shmuel, Bruno's life would be extremely boring and lonely. Similarly, the time Shmuel spends engaging in pleasant conversations with Bruno offers him a much-needed respite from the horrific conditions inside Auschwitz.
Neither boy despises the other for their ethnicity or religion, which allows their friendship to flourish. Even though the boys desperately wish to play together without the dividing fence separating them, their conversation and company mean everything to the boys. Bruno even begins sneaking food to Shmuel and looks forward to their meetings throughout the week. Both boys are able to meet up at a distant part of the camp away from the prisoners and guards, which allows them the necessary privacy to develop a friendship. In the end, Bruno finally crawls underneath the fence to the other side, where they tragically die in a gas chamber looking for Shmuel's father.