The theme of friendship in The Boy in the Striped Pajamas can be seen throughout the film.
From the film's exposition, Bruno underscores the importance of friendship. He misses the friends that he has left behind in Berlin. He never forgets the fact that while his father and his sister might be enjoying the new world of "Out- With," Bruno is lost without friendship. The fact that Bruno does not waver in his commitment to friendship from the start of the film underscores the theme. It helps to frame the work because it establishes a significant way we get to know Bruno.
Another way that friendship is reinforced in the film version of Boyne's book is when Bruno acknowledges that he was not a good friend to Shmuel. When Bruno witnesses Kotler beating Shmuel up for something that he did not do, Bruno remains silent. He watches as his friend is abused. Bruno acknowledges his mistake to Shmuel. In doing so, he reaffirms the importance of friendship. It has to be protected and when it is not, restoring it through forgiveness is essential. Bruno shows this in his actions towards Shmuel.
The final moments of the film also reaffirm the theme. Bruno and Shmuel set off on their great adventure. However, the horrifying nature of what surrounds them becomes very clear. Both boys are herded into the gas chamber. Uncertainty and fear dominate their emotions. However, both boys do not abandon one another. They remain true to their friendship until the very end as they walk hand in hand towards their deaths. The theme of friendship is validated in how both boys do not sacrifice their loyalty to one another even in the face of terrifying fear.