Mo is a supremely well-intentioned girl, but she's definitely got a mouth on her… and sometimes it gets her into trouble. She always says exactly what she's thinking and tells the honest-to-Bob truth, even if it makes other people uncomfortable. For example, she points out Mr. Jesse's mistress aloud at his funeral service and seems incapable of shutting up around Detective Starr—much to his annoyance.
Mo can't even stay calm and play along when Robert Slate calls and Detective Starr asks her to keep him on the line for as long as possible:
I shrugged, awash in misery. Why can't I ever keep my mouth shut. Why didn't I do what Starr told me? "I guess so. The line was too scratchy and far away. It sounded like… I don't know. Like something metal. Something creaking…" (21.76)
She immediately starts freaking out and demanding to know where the Colonel and Miss Lana are because she's so upset. So yeah, her intentions are good—she wants to help, after all—but her mouth gets away from her a bit.
Despite the fact that Mo often wears her heart on her sleeve, she is definitely a resilient kid who manages to get through a lot of hard times. First of all, she has a difficult beginning in life because she doesn't know her real parents. She was set afloat in the creek as a newborn to escape the hurricane. Plus she's been raised by the Colonel, a guy whose no-nonsense approach to parenting is pretty militaristic. He has her using military time, manning the café in his absence, and calling him "sir" when she talks to him. Talk about strict.
But all this military training comes in handy when Mo's guardians go missing. Instead of flailing about in her grief and fear, Mo bucks up like a brave little soldier and makes things happen. She starts her own detective agency with her best friend Dale, and together they launch their own investigation independent of the police.
They even gather up the courage to go into an abandoned house to search for Miss Lana:
I took a deep breath. The Colonel says sometimes all a leader can do is see which way everybody's going, and try to get in front. This looked like one of those times. "Okay," I said. "We'll both take the door. Follow me." I crouched low and sprinted across the yard to the pump house, Dale on my heels. (24.30)
Even though Mo is scared of the abandoned house—and even more scared of running into a deranged killer—she grits her teeth and walks straight into danger. What a brave trooper.
As brave and brash as Mo is, there is one sore spot in her life. Her name is Moses because she was fished from a creek as a baby, and because of this she doesn't know her real family or where she's from. Even though Mo is surrounded by plenty of love and community, she still longs to know her real family, especially her mother. She writes letters to her upstream mother constantly, placing them in bottles to float down the creek in the hopes of reaching her. She even has a map of all the places she's checked on her wall:
The sprawling map of North Carolina, which Miss Lana helped me tape up on the wall above my bed, pinpoints my search for my Upstream Mother. Using the process of elimination and a set of color-coded pushpins, I've marked all the places I know she's not. (3.4)
Mo never does get an answer to her letters, but in the end she decides this is okay. She has the Colonel, Miss Lana, and all of her friends in Tupelo Landing, after all, and they love her to pieces. Almost losing her guardians makes Mo realize that her real family has been right in front of her all along. She doesn't need to keep searching for a stranger to truly come home.