This quotation actually can be found in Chapter 14 (rather than Chapter 12) of To Kill a Mockingbird. Jem and Scout had just gotten into a fist fight earlier in the evening. Jem had threatened to "spank" his sister, so, after calling him a "damn morphodite," Scout went on the attack. It took Atticus to break them up and send them to bed. But shortly afterward, Dill suddenly appeared from under Scout's bed. He had run away from home and hoped to hide out in Scout's room for a while. But Jem knew that Dill's parents would be worried, so he decided to break "the remaining code of our childhood": He ratted Dill out to Atticus. But it was all for the best, as Jem knew it would be. Atticus broke the news gently to Dill's Aunt Rachel, and Dill got to spend the rest of the night in the Finches' house--and what must have been an interesting night sharing the bed with Scout!
In Chapter 14, Dill runs away from his home in Meridian to Maycomb, where he hides underneath Scout's bed. When Jem and Scout are heading to bed, Scout accidentally steps on Dill. Scout initially thinks that she stepped on a snake and calls Jem to inspect underneath her bed. Much to Jem and Scout's surprise, Dill crawls out from underneath the bed. Dill then explains to Jem and Scout how he managed to run away. After Jem hears Dill's story, Jem tells Dill, "You oughta let your mother know where you are" (Lee 86). When Jem gets up and leaves the room to tell Atticus that Dill ran away from home, Scout writes, "Then he rose and broke the remaining code of our childhood" (Lee 86). The remaining "code" of their childhood refers to Scout's sibling trust. Scout feels betrayed by Jem, who decides to tell their father that Dill ran away. Fortunately, Atticus handles the situation and allows Dill to spend the night at their home.
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