The most basic conflict that all of the characters face in The Book Thief is how to make sense of a world where so little makes sense. There is a fundamental challenge in how the individual characters wrestle with the world of the Nazis. Even Death, who notes how busy he is during the time, struggles with the way of the Nazi world, as evidenced in the book he gives back to Liesel when both of them meet.
Hans struggles with the reality of the Nazis and the Gestapo in how he lives his life, apart from the Nazi watchful eyes. Liesel struggles under the weight of death and suffering that she experiences. This is both personal, with the absence and death of her mother and brother. Yet, it is also social in terms of how she sees people she knows and loves sacrificed under the persecution of Nazism. Rosa carries an exterior that would rebuke the world, a countenance that can be seen as a response to the terror of the Nazis. However, she struggles with protecting those she loves, and like Hans, dies as a result of being unable to reconcile the way of the world with what should be. Rudy's love for Liesel is not a value reciprocated in the world around him. The kiss he so longed for was something he can only receive after the bombing of Himmel Street in which he dies. Max struggles with his own sense of guilt over not representing his own family in a defining moment, but also faces pain and hurt over having to live his life in the wake of the Nazi regime's desire to control everyone and everything. The world that the Nazis created is one where there is little in way of love, logic, and compassion. The characters in the novel who are all feeling and representative of the transformative capacity intrinsic to human nature struggle within this reality.
The basic collision between what is within life under the Nazis and what should be as seen in how the characters seek to live life forms the central conflict that all of the major characters must endure. No one is able to fully escape the reality of this conflict. In each of their own ways, the characters suffer because they cannot fully capitulate and assimilate to the Nazis, the embodiment of that which is evil and that which is repugnant. The price of their dissent and their refusal helps to seal their own fate of pain and suffering as a result. It is in this light where the central conflict of human beings seeking to live life as it can or should be in light in direct opposition to what life actually is defines the individual characters in The Book Thief. The net effect on the reader is that one understands the pain and suffering in resistance. However, it becomes clear that, given what is at stake for each of the characters and the upholding of a set of guiding values, there can be no other choice. This central conflict is what ends up forming the novel's narrative structure.