All sass and spirit, Moody makes a big impact on Ben. Unafraid to tell the world what she really thinks, even though she's not supposed to as a Black girl, Moody is defiant and proud. Importantly, this positions her as Abraham's opposite. As much as he's the model of wisdom and clarity, Moody represents the angry, emotional woman who emerges in response to a lifetime of racism and oppression. We might get a whiff of sexism here—Abraham responds reasonably, Moody responds emotionally—but either way, as much as Abraham's a type instead of complex character, so, too, is Moody.
The only crack in Moody's tough-girl façade happens when her brother dies. As Ben explains:
Moody looked into my eyes. For the first time since we'd met, she didn't look the least bit feisty or defiant. She looked downtrodden. Defeated. (65.13)
Moody's heartbroken, which makes perfect sense given that her brother's just been murdered. In terms of her character in the book, though, this is a rare moment in which Moody is presented as more complicated, as nuanced and fluctuating instead of a sort of feisty constant. This positions her anger and brazen attitude as defenses she uses to hide the fact that she's upset over the unfair treatment that governs her life. Since the rest of the time she pretty much just stomps around and serves as a lust object for Ben, we'd say this is a pretty significant moment.