Faith and Religion
Gerda considers faith essential to her life before the Holocaust. Faith proves essential to her survival through the ordeal, but she loses religious faith, e.g. that of prayer. Ironically, in her survival, she loses the value that is essential to her for survival.
Love
Gerda and Abek risk their lives helping each other through their persecution. The popular expectation of friends, family, and himself is that she would romantically love him. However, ironically, she is incapable of romantically loving the man for whom she risks her life just to see.
Luck and Survival
Several times throughout the story, Gerda makes rash decisions that others expect will prove fatal. Most notable are her decision to be deported from the Sosnowitz ghetto and her decision to flee the Nazi death march. In the prior, the allegedly safer ghetto proves the opposite once its inhabitants are exported to their deaths shortly after she decides to leave. In the latter, deciding to flee the Nazis, which the girls determined to be best for their survival, proves to likewise the opposite; Gerda luckily postpones enough on fleeing to see similar girls executed who try just before she would have. The irony between expectations and reality appears repeatedly, such as in the circumstantial prevention of her contemplated suicide.
Intimacy and Distance
Ironically, Gerda feels most intimately invested in her love ones when they are distant. She does not fully appreciate them until they are taken from her. This irony manifests itself in her letters, which come to discuss increasingly familial and mundane topics, expected between physically close people, as the distance between her and her loved ones increases to the point where she knows they are dead. Such irony takes root in her denial of her unseen family's and friends' fates; this denial is a coping mechanism by which she psychologically survives the Holocaust.
Humanity
Even though their Nazi tormentors attempt incessantly to dehumanize them, the girls with whom Gerda commiserates only manifest further their humanity as their environments demand otherwise. Ironically, the more animalistic of situations to which the Nazis subject them, the more human the girls become. For example, even though food rations are incredibly deficient in all of the camps in which Gerda is interned, the girls take measures to see that everyone is well. Even though they themselves are starving, some girls at Landeshut snuck the more impoverished men bread. Overall, the reality of the Nazi's victim's collective character stands in irony with the Nazi portrayal and intended demoralization of them.
