The kid “Petey” who is the main protagonists brother is a bit of a mystery. Seems very intelligent on one hand, and utterly terrified of change, of food, of sports, of dogs, the outdoors etc. It’s borderline autistic.
Is there a back story about why he is so terrified of change and new things? I’ve never seen a child portrayed in daily comics with such a huge clump of neuroses.
He’s just comically exaggerated in his dislikes, his OCD, and his withdrawal, particularly in contrast to his little sister. He interacts with her and his cartoon-camp friends reluctantly, but not autistically. Note that he has one friend (Ernesto, I think his name is) whom he believes to be imaginary. Ernesto insists that he is real, but Petey only happens to see him when no one else is around.
Think of Ralphie’s little brother in A Christmas Story, who liked to sit in the cabinet under the sink.