Arthur Radley (Boo)
The Mysterious neighbor who piques the children's interest. They've never seen him and make a game to trying to persuade him to come to the outdoors..
Why do the children fear him?
Boo is feared because they think he is insane. They imply he is because he has never left his house and has never ever been seen before.
In the end , what do the children think of Boo?
"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."
They understand that the real world is a harsh reality and maybe he stays inside to stay away from the evil of humanity.
After he saves the children , he is seen for the first time and the children understand Boo's more than ever.