How is Salva's character changing throughout chapters 1-4

Salva is by all accounts an incredible figure, and one most people would deem heroic, but Park writes him in a very relatable, human way. He is a little stubborn, a little dreamy, a little weak. He doesn’t understand everything that is going on around him. He is a real child who desperately misses his family, wonders what will happen to himself, and spends time lost in the memories of the life he once had.