Noticing how scared RiRi seems of a possible wildfire indicates again that Frenchie is beginning to come of age: he's starting to see RiRi as more of a full, multifaceted person in her own right, not just a little kid in need of his protection. Frenchie recognizes that her history is her own, and it's not something that he can necessarily protect her from. That Frenchie takes pride in being able to climb the tree illustrates how Frenchie's identity is becoming increasingly tied to his role as a protector.