If I am not mistaken, he saved them at the end of the novel from whoever attacked them in the night and escorted them back to their home where Atticus awaited.
In "To Kill a Mockingbird" by Harper Lee, Jem, Scout, and Dill play a game called "Boo Radley." They act out various scenarios and create stories based on the mysterious neighbor, Boo Radley, who they have never seen.
Scout is surprised because she has always seen Dr. Reynolds as a serious and professional figure who would not interact casually with someone like Arthur Radley, who is known as a reclusive and mysterious figure in Maycomb. The interaction challenges Scout's preconceived notions about how people in the community perceive and treat Boo Radley.
Jem says that Boo Radley must not be at home because he's never seen him before. The irony is that Boo Radley has been watching over Jem and Scout all along, and cares for them even though they are not aware of his presence.
When Atticus asks Scout about the blanket around her shoulders, Jem realises that it was infact Boo Radley that had put the blanket around her shoulders to keep her warm while watching the blazzing fire at Miss Maudies, and that if they hadn't been so ingrossed in the fire, they would have seen Boo.
Thieves in his garden patch. (Actually, it's Scout, and her brother and Dill trying to get a peek at Boo Radley. Later, her brother's pants is found folded near the barbed-wire fence where he lost it during their hasty departure.)
Mr. Arthur Radley, also known as Boo Radley, is reclusive and rarely seen outside of his home. He is rumored to have been involved in a violent incident in his youth, which has led to his isolation. Despite his reputation, he shows kindness and consideration towards the Finch children, Scout and Jem.
Arthur "Boo" RadleyArthur Radley is more commonly known to Scout, Jem and many other characters as Boo Radley. Boo is the shut in, the man who lives in the house down the street from Jem and Scout but never comes out. He hasn't been seen for years. It is a rumor that Boo hides out, not because he wants to but because he has been forced to as of the day he allegidely stabbed his father in the leg using a pair of scissors, however I believe this is proved to be untrue later on in the book.
Nathan Radley is Boo Radley's brother. In the novel, Mr. Radley tries to break up Boo's and Jem's and scout friendship by putting cement to one of Boo's treasure which was for Jem and Scout. Nathan simply tells the boys that he was trying to revive the tree, because is dying.
Scout was surprised and touched when she realized Boo had been watching over them and had placed a blanket around her shoulders as they watched the fire. It was a poignant moment that showed Boo's kindness and care for the children.
Scout wants to see Boo Radley in person because he is a mystery to her. Sitting in the dark shadows allows her to observe the Radley house without being seen, hoping to catch a glimpse of Boo. This curiosity and intrigue drive her to seek out Boo despite the risks.
Boo Radley first came up when Miss Maudie's house was on fire because he put a blanket on Scout. He actually was seen for the first time by Scout and actually made an appearance in the book at the end when he saved the children and was sitting in Jem's room.
In chapter 8, Boo Radley shows kindness to Scout by placing a blanket around her shoulders during the fire at Miss Maudie's house. Despite Scout never having seen him do it, Boo displays compassion and concern for her well-being in this moment of need. This small gesture illustrates Boo's quiet and understated care for the children in the neighborhood.