Harper Lee treats Arthur Radley with respect and dignity. However, the other characters of the novel do not always do the same. In the beginning, Scout sees the world through the eyes of an 8-year-old. Boo is a mythical creature to her, someone hidden from the eyes of the world. Her only information is wild rumors and clearly false gossip. Jem and Dill are no better, and they encourage Scout's fear and awe of Boo. Yet throughout there is a sense that this man will not turn out the way they think. Indeed, early on, Boo proves his good nature by placing a blanket over Scout's shoulders on the night of the fire. In the end, he saves Scout and Jem's lives, and removes a threat to the town itself, by killing Bob Ewell. He develops into a well-mannered, polite, shy, reclusive man, who only wants to be left alone.
As far as his role in the story, Boo serves as a catalyst for Scout and Jem's maturation. Their view of his character at each point in the story gauges how far they have come in their own growth. As their perception of Boo changes, they themselves change into compassionate young adults.