What is so unusual about Doodle?

Lots of things are unusual about Doodle, but probably the easiest unusual trait to identify deals with his physical features. Doodle was born with a physical disability. In fact, most people did not think that Doodle would survive very long after birth.  

He was born when I was six and was, from the outset, a disappointment. He seemed all head, with a tiny body which was red and shriveled like an old man's. Everybody thought he was going to die—everybody except Aunt Nicey, who had delivered him.

It is likely that in addition to his physical disabilities, Doodle has a mental disability. His mother tends to think so, but his brother (the narrator) does not believe so—or he chooses to ignore that possibility altogether, because he vows to help Doodle reach his full potential and be like any other little brother.

I feel, however, that what makes Doodle so unusual is his personality. He does know that he is different because of his physical disabilities, but that doesn't let him stop loving life and playing with his brother. In fact Doodle would do just about anything to earn the acceptance of his brother, and he would do it with a cheerful heart. Doodle has every reason to be angry at the world, but he isn't, and that is why I think Doodle is such an amazing and unusual character.