Josef, twelve years old at the start of the book, is one of the three protagonists of the novel. Josef is brave, mature beyond his years, and devoted to his family. From the opening scene of the novel, Josef shows a strong desire to be seen as an adult, which sometimes causes tension within his family. When Nazi storm troopers invade his home and seize his father, he fights against them, showing bravery that characterizes his actions throughout the book. Rather than hiding or using his age to ask for mercy, actions of a child, he insists that he is almost an adult, an example of his wish to be seen as an adult. However, after the trauma of the concentration camp leaves Aaron unable to return to his role as a parent, the premature adulthood refugee life forces on Josef causes tension within the family and within himself. After slapping his father and frightening him into submission in order to pass the port authority health screening in Havana, Josef feels guilty for scaring him and also for “taking his father’s place as the man in the family,” an example of the theme throughout the book of how refugee children are forced to behave as adults.

Although Josef shows immense bravery and maturity throughout the book, he is still a child, and there are limits to his ability to protect his family. After Aaron tears the room apart in a spell of madness and Rachel accidentally ends up drugged to sleep while Ruthie is at the pool, Josef’s inability to care for his parents and sister at the same time ends in the permanent separation of the family, since Aaron jumps overboard when Josef leaves him to pick up Ruthie.  Josef helps Pozner stage a mutiny, but when the captain challenges him about how he plans to pilot the ship, he is forced to back down, an example of his will to take bold action being frustrated by the limitations of his knowledge and experience. In the cruel choice the Nazi soldier gives to Rachel, of which child she will save with the bribe of her diamond earrings, Josef is again defined as a child, not an adult. However, in his decision to volunteer himself, sparing Ruthie’s life and Rachel the agony of an impossible choice, he shows the courage and self-sacrifice that characterize his actions throughout the novel.