Explain how Jem’s allusion to the fairy tale when he calls Scout “Three Eyes” relates to the theme of this story.

In chapter 6 of To Kill a Mockingbird, Scout is having difficulty sleeping because every sound she hears is attributed to Boo Radley. Jem asks her, "Sleep, Little Three-Eyes?" This is an allusion to a Grimm fairly tale about three sisters. In the fairy tale, the oldest sister has one eye, the middle sister has two eyes, and the youngest has three eyes. The oldest and youngest are unkind to the middle sister because she is ordinary with just two eyes. It is the sister with three eyes that pretends to be asleep while she is actually using her third eye to watch the middle sister. Jem calls Scout "Little Three-Eyes" because he knows she's awake when she should be sleeping. He informs her that he'll be going to the Radley place to retrieve his pants, and he doesn't want her to tell Atticus.
It is possible to see a connection between the theme of the fairy tale and one of the themes of To Kill a Mockingbird. In the fairy tale, two of the sisters are mean to the other sister because she is seen as less important. In their minds, she is only worthy of eating their leftovers at mealtime. Consider how the citizens of Maycomb County view Tom Robinson and the other black citizens. They are seen as inferior because of the color of their skin in much the same way that the middle sister is seen as inferior because she only has two eyes.