The character of Bruno is such an amazing one. His identity is shaped on his own, not by what others think it should be.
At the beginning of the novel, Bruno is living in Berlin and very happy. He has three best friends Karl, Martin and Daniel, and they swear to be best friends for life. When Bruno has to move to Poland, he eventually forgets his friends and their names. We see at the beginning, that Bruno is a strong willed boy and wants thins his way. He doesn't want to leave his friends and family. He is angry that he has to leave.
In the middle of the story, we see that Bruno is a very active boy. He longs for adventure. He is told that he can not go to far from his house. Being an adventurous boy, this just fuels his fire for adventure. He becomes friends with a "farmer boy" on the other side of the fence. He doesn't know that this a concentration camp. The two boys become friends, and Bruno sneaks his new friend food when he can. We see that Bruno has a big heart and is very kind. He is also very friendly. He still misses Berlin, but is slowly starting to feel like this new place is home. He doesn't agree with the Nazi way of thinking, and thinks for himself. He is becoming more mature.
By the end of the novel, we see that Bruno is a boy with his own mind. He doesn't think of the consequences that this will lead to. He still very much loves adventure. He and Shmuel are the best of friends. Shmuel's father has gone missing and Bruno offers to come in the fence and help his friend. He puts on a pair of striped pajamas and enters the camp. He thinks this is nothing more than an adventure to help his friend. He doesn't yet realize that this will be his last adventure.
The identity of Bruno is pretty steady throughout the story. We see him become more of his own person. He thinks the way he wants to think and it doesn't matter what the others think. He longs for great adventure and finds it. He is a kind and gentle boy. Bruno's character has come to symbolize light in a time when there was just darkness.