In The Boy in The Striped Pajamas, Bruno has made a friend of Shmuel, a boy from the other side of the "fence," despite his parents' having forbidden him with "no Exceptions" from exploring near there. As he packs his pockets with food for Shmuel, Maria surprises him, catching him taking food. She assumes he is just hungry again.
Bruno has been wondering about something that Pavel, " The man who comes and peels the vegetables and then waits on us at table" had said to him after Bruno had fallen and hurt himself previously and Pavel had attended to him. Bruno would have thought nothing of it except that Pavel told him he was a doctor. "He's not a doctor, is he?" is Bruno's question to Maria who is stunned and a little afraid at his question which puts her on her guard as she knows the strict rules she must abide by. Maria explains that Pavel is not a doctor but "In another life" he was - "before he came here."
Maria shares what information she knows about Pavel's life "before" which seems to satisfy Bruno but the reader must draw his or her own conclusions. Maria has always been very cautious and ensures that she never speaks out of place. As Bruno is the narrator and has no concept of Maria's fears, again it is left to the reader to assume how afraid of Bruno's father she is.