What do Ricky's Hats represent?

Lily and Sam's father passed away in a car accident that happened during rainy weather. From that point on, Sam has always had a fear of cars, but particularly of driving in similar conditions. When the rain begins pouring at the end of the novel, just as Sam and Lily are about to drive off to the hospital to see Halmoni, it symbolizes fear because it is what Sam dreads the most and surrounds her, suffocating her and causing her to feel paralyzed behind the wheel. When Lily gets the tiger to 'guide' the girls through the rain, she is symbolically getting her sister to face her fear, to quite literally force her way through it, and to believe that everything will be alright despite all evidence to the contrary.