We guess you get the picture. Each of the narrators is sunk in grief that pervades their narratives. Sure, we gets moments of humor from Oskar's eccentric interests and naïve observations, but for the most part the tone ranges from serious to downright bleak. Oskar's grandmother's letters have glimmers of hope, but they're just glimmers. His grandfather's letters just bury the reader in hopelessness and emotional numbness. The author wants to show us that ultimately, love can help us manage sorrow, but in overall tone, we think sorrow wins.