When Felix muses that it’s “hard being an orphan if you haven’t got an imagination,” he implies that children use stories to escape pain, but he doesn’t yet realize that the stories he’s been telling himself about his parents may be similarly escapist. This passage also suggests that the stories children invent tend to be self-centered: though Felix names his story’s protagonist William after Richmal Crompton’s
Just William series, the detail about living in a mountain castle for “three years and eight months” indicates that “William” is a stand-in for Felix, who lived in a mountain orphanage for exactly that long. In the same vein, Zelda’s reminder that she’s a girl implies that she wants a story with a female protagonist based on her.