What evidence is there that Boo might wish he could have grown up like Jem and Scout, and at what point did Boo discover that he could do more than simply observe Jem and Scout?
I need to find a quote that shows taht he is wishing he could have grown up like, or alongside Jem and Scout, wishing he could be more like them, wishing he could even be them. Radley is starting to realize that he can do more than just observe; he can protect, as he does in the final chapters, saving Scout and her brother from Bob Ewell.
It's difficult to speculate what Boo Radley might have wished, as we don't actually see him until the final pages of the novel, and he barely speaks then. However, one might infer from the little treats he leaves the kids--the Indian pennies, gum, soap figures he carved of Jem and Scout, an old pocket watch, a spelling medal--that he feels a kinship with the Finch kids, affection perhaps. There is the time that Jem and Dill roll Scout in the tire into a tree, and Scout thinks she might hear laughing inside the Radley house. Finally, we see that Boo knows more about what's going on in town than anyone would've guessed, when he saves the kids from Bob Ewell. For whatever reason, he was keeping an eye on the Finch kids that night, and perhaps other times as well. Perhaps he knew about Ewell's threats, or perhaps he just liked to keep an eye on them as a tenuous link to his lost childhood. In any case, he saved their lives, leading Atticus to thank him "for my children".