How does Bruno's character grow throughout the novel The Boy in the Striped Pajamas?

In the beginning of
the story, when Bruno has to leave his home and friends in Germany because of his father's
promotion, he has a negative, self-centered outlook on the situation because he has no desire to
leave the familiar environment of his home in Berlin and his friends there. However, once he and
his family move out to the countryside, Bruno's natural curiosity leads him to explore his new
surroundings, even though his father forbids it, and this exploration allows him to grow as a
character because he comes face to face with a very different world than the comfortable one he
has enjoyed all his life.

One day, during an exploration, Bruno comes across
a camp that he has seen from his house. It is surrounded by a barbed wire fence, and he sees, to
his surprise, people wearing stripped pajamas inside it. Intrigued, Bruno visits often and soon
becomes friends with a little boy named Shmuel on the other side of the fence. This meeting is a
turning point in the growth of Bruno's character because he becomes more focused on the needs of
his new friend than on his own, and his unhappiness at being far from Berlin fades to the back
of his mind. For example, when he realizes that Shmuel is hungry, he sneaks food to him through
the fence. Bruno's character growth is most strikingly illustrated at the end of the book when
he finds a way to dig under the fence to help Shmuel find his father, a selfless decision that
contrasts strikingly with his self-centeredness at the beginning of the
novel.