Jack is the first-person protagonist through whom readers experience the story. He never confirms his age, but his classroom descriptions and speech suggest that he’s a late elementary school student. In Jack’s first few journal entries, he demonstrates a stubborn exterior, which derives from insecurity. Jack seems to disregard Miss Stretchberry’s instructions based on the entries’ lack of content. But Jack reveals his deep-seated insecurities when relinquishing a poem to his teacher: “Do you promise / not to read it / out loud? / Do you promise / not to put it / on the board? / Okay, here it is, / but I don’t like it” (4). He fears his classmates’ opinions; the final line also suggests that Jack is either his own worst critic or he always prepares for the worst. The latter is consistent with his experiences; Jack loved Sky unconditionally, but the worst-case scenario still happened. Either way, Jack works to overcome these insecurities and step outside of his comfort zone.

After readers break through Jack’s stubborn exterior, they discover his innocent and sincere heart. He’s quick to uplift others’ writing, as he does for a classmate’s tree poem.