"Avatar: The Last Airbender" explores themes of destiny and fate through the character of Aang, who is the Avatar and has a significant role in bringing balance to the world. Throughout the series, Aang struggles with accepting his destiny and the responsibilities that come with it. The show also delves into the idea of destiny versus free will, as Aang must make choices that ultimately shape his own path. Additionally, other characters such as Zuko and Katara also grapple with their own destinies and the choices they must make to fulfill them. Overall, the show presents a nuanced exploration of destiny and fate, showcasing how characters navigate their predetermined paths while still retaining agency in their decisions.