One of the reasons we find ourselves attached to Mia so quickly is because she talks to us as if we were her friends. Take her opener, for example:
I'll never forget the first time I heard the word, that day at the blackboard. It was five years ago, when I was eight. (For those who are mathematically challenged, like me, that means I'm thirteen now.) (Pro.2)
We know she's talking about a traumatic experience (being called a freak), but she describes it in such a lighthearted way. She even throws a joke in there for those of us "who are mathematically challenged." We can tell that Mia is comfortable talking to us because of the carefree tone she uses even when she's spilling the beans on a big secret—like having synesthesia.
But there are also times when Mia offers up such heart wrenching sadness that we want to cry along with her. The best example of this is when (spoiler alert) Mango dies. She tells us:
I still have my seat belt on and am hunched over my knees, gagging. It feels like someone kicked me in the stomach, only a hundred times worse. (14.1)
Ouch. We can really feel her pain in this passage. We know it's rough for her to see Mango die, but not because she comes right out and says it—we can sense the emotions in her words. Mia allows us to feel what she's feeling simply by switching up her tone.