Kind AND patient? Maybe not.
I'm not sure about the patient part. I would say that as the novel progresses, Bruno does become more patient than he was at the beginning. This is evidenced by his willingness to spend time talking to a boy who lives on the opposite side of a prison camp fence time and time again. At the beginning of the book though, I'm not sold on him being patient. Bruno does not want to move to the new house (which is expected), and after arriving in "Out-With" he complains a lot about being bored and not having any kids his age around. While this is something expected from a nine-year-old, it doesn't exactly scream patient.
He is kind for sure. He is willing to spend time simply talking to a boy that he can't actually play any real games with—definitely no sports. Also Bruno has a heart for helping Shmuel find his dad. However naive Bruno may be about what is actually happening inside that fence, he has to have some apprehension about crossing over a fence. What nine-year-old wouldn't? But despite that, Bruno decides that helping his friend find his father is important. So he goes, and pays for it with his life.