This is a difficult question to answer, since we know so few facts about Boo. We do know that Boo is never seen, and he deliberately remains inside the Radley House. He protectively values his privacy, resorting to reclusiveness in the extreme. Even though he befriends the children through his presents in the secret knothole, he refuses to introduce himself. Instead, he watches them play outside through his window curtains; he passes, like a mere shadow, on his back porch while Jem cowers nearby. It is enough for him to give the presents in the hope that the children will enjoy them; he needs, nor wants, their companionship, but only to see their happiness. These acts show his innate kindness and generosity, and he will display them even more instinctively at the end of the story when he comes to the children's aid--in the flesh. In this act of protection from the hands of Bob Ewell, Boo also shows a courageous side; he has shown it before, taking the risk of exposing himself to mend Jem's pants and warm Scout's shoulders. Even when Scout finally meets him, she recognizes how "timid" he is, hiding in the shadows
... against the dull cream wall in the dim light of Jem's room.
But she has also discovered that he is their friend and protector, and
Boo was our neighbor... But neighbors give in return. We never put back into the tree what we took out of it: we had given him nothing, and it made me sad.