In the book The Book Thief, how would the story have been different if Liesel had not continued to have nightmares about her brother?

I think the nightmares about her brother were a way her mind dealt with his death and her circumstances. Without this haunting imagery, Liesel would not have developed into the same heroic character that she becomes. It is her pain over her brother that makes, at least in part, Liesel so beautify. It is a paradox in this story that pain can cause such courage.