In Chapter 19, when Tom Robinson is testifying, Scout realizes how lonely Mayella and Boo must be. She says, "As Tom Robinson gave his testimony, it came to me that Mayella Ewell must have been the loneliest person in the world. She was even lonelier than Boo Radley, who had not been out of the house in twenty-five years." Instead of viewing him as a monster, she considers how lonely he must be.
At the end of Chapter 23, Jem and Scout are discussing social classes and why certain people do not get along. Scout thinks there is just one type of people. The reason the Cunninghams are different from the Finches is based upon their lifestyle and income. Walter Cunningham Jr. could be as smart as the other children but he spends too much time working. Jem adds that he used to think this way. But as he's gotten older, he realizes that people segregate and separate themselves. He then suggests that this conflict between people might be the reason that Boo Radley stays in his house.
“That’s what I thought, too,” he said at last, “when I was your age. If there’s just one kind of folks, why can’t they get along with each other? If they’re all alike, why do they go out of their way to despise each other? Scout, I think I’m beginning to understand something. I think I’m beginning to understand why Boo Radley’s stayed shut up in the house all this time… it’s because he wants to stay inside.”
In Chapter 31, after Boo has saved the children from Bob Ewell, Scout walks him home. After parting, she thinks, "Boo was our neighbor. He gave us two soap dolls, a broken watch and chain, a pair of good-luck pennies, and our lives. 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." Scout feels bad that Boo gave her so much and she gave nothing in return.
She stands on Boo's porch and takes a comprehensive view of the street and houses. She recalls one of Atticus's lessons which is to always consider other people's perspectives. One does this to understand other people for all their goodness and all of their flaws. In this moment she tries to put herself in Boo's shoes. She tries to think about how he sees the world.
Atticus was right. One time he said you never really know a man until you stand in his shoes and walk around in them. Just standing on the Radley porch was enough.