In a letter at the end of Purple Heart, author Patricia McCormick states that the novel is “an attempt to portray how three children—two eighteen-year-old Americans and a 10-year-old Iraqi boy—have been affected by war” (207). While the 10-year-old, Ali, is obviously a child, 18-year-old Matt and Justin are ostensibly adults, given the responsibility of fighting and potentially dying for their country. However, McCormick adds details throughout to remind the reader of how young Matt, Justin, and many of their other squad members really are.

Matt, too young to drink, thinks that once he gets home “it would be a lot easier to find someone to buy him a six-pack now that he was a vet” (164). He’s also “never been a very good smoker” (79), unable to hit the right balance when inhaling, and Wolf always asks him “to show ID” (79) when he’s bumming a cigarette. Justin and Matt’s favorite pastime is playing Halo, and Justin loves to use his word-of-the-day calendar to make immature jokes. One of Matt’s best memories of the squad is the time Justin, Wolf, and all the others played with a can of Silly String, “playing war” (53) like children in the midst of the real one.