Initially I would imagine someone who stole books to be somewhat more calculated than other robbers. Most robbers wouldn’t steal books, as they aren’t extremely valuable. For someone to actively steal books means that they have ulterior motives then just random stealing.
Early on in the text: These early experiences in Liesel’s life changed her in a number of ways for example after her brother dies right in front of her she experiences nightmares for years afterwards. This is a major event in her life, and one she remembered for the rest of her life. After her mother gives her up for adoption, Liesel seems, for quite some time, to be in denial. Constantly telling herself that her mother will come back for her as well as trying to write various letters to her. Only after receiving no reply for weeks on end that Liesel finally accepts the fact that she will probably never hear from her mother ever again.