One of the most important themes of The Hidden Oracle is Apollo’s growing acceptance of his mortality. Initially, Apollo is horrified to have his superhuman powers taken away. He frequently rails against Zeus for making him a mortal, despises his teenager’s body, and wonders how mortals survive their limited existence. When he is beaten up by thugs, he laments at seeing blood instead of “golden ichor” leak out of his wounds. Since Apollo was known for his power and beauty, his flawed human appearance offends his vanity. He even mocks humans for living in tiny apartments, wondering “Where is your pride? Your sense of style?” (27). However, as the plot progresses, Apollo undergoes a subtle transformation. Though his body and mind are limited, he finds his emotional capacity expanding and experiences feelings such as guilt, love, and empathy. Apollo admits that gods, who are surer of their actions, do not generally harbor such intense emotions. Thus, being mortal gives Apollo opportunities to grow in a different direction.

However, the plot of the novel is not just about Apollo accepting his mortal form. Instead, it delves into the powers that mortality itself confers. In Chapter 8, Apollo admits that all gods actually fear death because “as you’ve seen, immortality can be taken away” (60).