Boo Radley is a huge focus of the children's in Part I of the novel; however, once part II begins, the Boo Radley story line takes a backseat to the new Tom Robinson story line. At the beginning of part II, Jem tells Scout to check out the porch "yonder." Scout looks up at the Radley Place, expecting to see Boo, as she has many times; however, the Radley Porch is empty. Instead, the formidable Aunt Alexandra is sitting on Scout's porch, looking as if "she sat here everyday of her life." We see in this example that the children are still slightly preoccupied with Boo, even though he's not in the forefront of their thoughts and behaviors as he was in Part I.
Another example in Part II is when Dill runs away from home and is found underneath a bed in the Finch home. Scout asks Dill, "Why do you reckon Boo Radley's never run off?" and Dill answers that, "Maybe he doesn't have anywhere to run off to." Again, Boo is a connection they are still making to their everyday events.
Finally, in Chapter 15, the reader learns that Dill has come up with a foolproof way to get Boo to come out of the house, but before the children can implement their plan, the new plot line of Tom Robinson emerges. The children become distracted by these events. Of course, Boo Radley returns to the action at the end of the novel when he saves the children from Bob Ewell.
Once we come in II part of the book, the children concentrate more on how Atticus faced the Ewells. More than Boo Radley, the children are worried aboutTom Robison and Atticus's court case. Jen even analyzes the disadvantages of being a lawyer.