The tone of the novel, told in the voice of Death, is at once pessimistic and hopeful. Death establishes this tone right away in Prologue: Death and Chocolate:
*** HERE IS A SMALL FACT***
You are going to die.I am in all truthfulness attempting to be cheerful about this whole topic, though most people find themselves hindered in believing me, no matter my protestations. Please, trust me. I most definitely can be cheerful. I can be amiable. Agreeable. Affable. And that’s only the A’s. Just don’t ask me to be nice. Nice has nothing to do with me.
Death wants the reader to go into the novel understanding that death is a part of life. "Nice has nothing to do with me," he writes. With this statement, he dismisses the idea that he is going to coddle anyone's feelings. Not only the reader, but also the characters in the novel are destined to die one day; the characters in the novel live in Germany during World War II, so they are likely to die sooner rather than later. The suspense of the novel will not be related to whether or not the characters live, but rather how long.
At the same time, Death is not interested in being grim for the sake of it, nor is he gleeful about how many souls there are to carry away during times of war. He feels grief and horror over World War II, perhaps even more than any human because he was present for every single death. However difficult it is to sit with this grief and horror, though, he would rather pay attention to humans than look the other way. He believes that there is a great deal worth seeing, even and especially during the worst moments in history. By accepting the grief and horror and moving past them, Death is able to appreciate the specific and varied human experiences these feelings would otherwise eclipse. Max and Liesel's friendship, Hans's accordion playing, and Ilsa Hermann's cookies are all evidence that humans can create joy and love under terrible circumstances. Death insists that these things matter, even if they don't make a difference in the grand calculus of the war. Even doomed characters can make a difference in one another's lives.