Claudia and Jamie complement each other, because Claudia is a rational planner, and Jamie is creative and impulsive. When deciding to run away, Claudia carefully lays out exactly what they will do, where they will go, which sibling to bring with her, etc. Jamie is a gambler, both literally and figuratively. He wins money from his friend Bruce—by cheating—which is one of the reasons why Claudia selects him as the sibling to bring. Jamie is also willing to take risks in real life. His impetuous behavior in the museum allows the children to find out vital information about identifying the statue. Near the end of the book, we see that the two have helped each other grow, as Claudia makes the impulsive choice to buy train tickets to see Mrs. Frankweiler. Prior to her journey with Jamie, it would have been quite unlike Claudia to do so, but she has learned from him. The result is that Claudia is able to "come home different," as she had said she wanted to do, with the knowledge of the statue that she could not otherwise have gained. So Jamie's presence on the journey was essential for even more reasons than Claudia initially realized.