* Hans Hubermann: While Hans is a central character and undergoes significant emotional development, he is presented as a fundamentally good and kind man from the start. His inner life is less explored compared to Liesel.
* Rosa Hubermann: Though Rosa is complex and multi-faceted, her character is somewhat predictable. She's a strong and tough woman with a gruff exterior, and her underlying tenderness is revealed gradually.
* Rudy Steiner: Rudy, Liesel's best friend, is presented as a loyal, adventurous, and optimistic boy. His character doesn't undergo much significant change throughout the novel.
* The Mayor's Wife: While sympathetic, the Mayor's Wife acts as a source of support and kindness for Liesel. She doesn't have a complex storyline or internal conflict.
* The Nazi Official: This character is meant to represent the cruelty and brutality of the Nazi regime. He is depicted as a heartless and menacing figure without much individual personality.
Important Note: Even these characters have some level of complexity and contribute to the story's themes. For example, Hans's unwavering kindness reflects the human capacity for empathy even in the face of unimaginable horrors. Rosa's tough exterior masks her deep love for Liesel and her vulnerability.
It's worth considering that "flatness" in a character can be a deliberate choice by the author to serve a specific purpose.
Ultimately, judging characters as "flat" or "round" is subjective. What matters most is how effectively they contribute to the overall story and its themes.