Reflective and Honest
Mattie is a born writer. We know this from how she describes the natural world and from how she interacts with the world in which she lives. And like many writers, Mattie gravitates toward reflection. She pays attention to detail, and her contemplative nature helps her process these details and add to her knowledge of people and the world, even when she's realizing unpleasant truths about herself. Check out this passage as an example:
My mamma left us. My brother, too. And now my feckless, reckless uncle had as well. My pa stayed, though. My pa always stayed.
I looked at him. And saw the sweat stains on his shirt. And his big, scarred hands. And his dirty, weary face. I remembered how, lying in my bed a few nights before, I had looked forward to showing him my uncle's money. To telling him I was leaving.
And I was so ashamed. (17.sesquipedalian.50-52)
It's this reflection that really allows Mattie to mature as a character and person. She wouldn't be able to grow if she weren't frank and honest, though there's a big difference between being frank with others and honest with oneself. Luckily for both Mattie and us as readers, she tends to be honest in her thoughts. Check out this little confession:
Royal talked a mile a minute as we rode. I nodded and did my best to listen, but I was thinking how much better Ample make this bed is than Make this bed amply, which is what I would have written. (33.gravid.6)
Even though she has an easy time communicating her thoughts to readers, Mattie has a harder time voicing her thoughts. She doesn't always say what she thinks, either at the hotel or to people in her life, because she is too often shut down by people who don't care what she thinks. Royal Loomis and his bratty brothers are prime culprits of this behavior:
Jim and Will howled with laughter. Royal didn't actually laugh, but he grinned. And I was silent the rest of the way home. (14.monochromatic.105)
Mattie also bites her tongue because she knows how powerful words can be. Her assessment of the deep wound Lawton left in Pa really shows this:
That's why Pa never smiled anymore. Why he was so angry. Why he looked at us but never saw us. Oh, Lawton, I thought, some things should never, ever be said. Words are just words, Royal would say. But words are more powerful than anything. (35.aby.76)
So because of Mattie's belief that words are inherently powerful, when she does choose to speak her thoughts, she says them with care. And her thoughts are mostly honest because Mattie believes that she has a duty to communicate the reality of life:
"Why do writers make things sugary when life isn't that way?" I asked too loudly. "Why don't they tell the truth? Why don't they tell how a pigpen looks after the sow's eaten her children? Or how it is for a girl when her baby won't come out? Or that cancer has a smell to it? All those books, Miss Wilcox," I said, pointing at a pile of them, "and I bet not one of them will tell you what cancer smells like. I can, though. It stinks. Like meat gone bad and dirty clothes and bog water all mixed together. Why doesn't anyone tell you that?" (22.glean.77-79)
With beef like that with other writers, you'd best believe that Mattie is going to tell this story reflectively and honestly. She'd be a raging hypocrite otherwise, which would be completely out of character for our main girl.