Stella is introduced as someone committed to following the rules and maintaining control in order to stay healthy and eventually get a lung transplant. However, it is revealed that Stella’s motivation is not necessarily her own desire to live. Rather, after the death of her sister, Abby, Stella feels she must stay alive so that her parents, who have since divorced, won’t have to grieve the death of another child. Stella spends the novel trying to protect her parents by withholding any bad news from them. She still mourns the loss of her sister and blames herself for Abby’s death, as Stella was supposed to go on the trip during which Abby died while cliff diving but could not due to being sick. In spite of her illness, Stella is extremely independent, taking all of her medications and administering other treatments without help and even taking an Uber to the hospital instead of asking one of her parents to drive her. All of Stella’s actions show that she cares more about other people’s well-being than her own.

This controlled mindset is why Stella feels so outraged upon meeting Will Newman, who is her opposite in several ways. She can’t stand that Will is not following his regimen and wants to help him. As the two get to know each other, Stella’s world opens up. She begins to think about having a life that is more fulfilling than being in and out of the hospital. Poe’s death is a turning point for Stella, as she realizes that she will inevitably die one day and thinks she should embrace Will’s outlook and enjoy life while she can. Her determination to walk to see the holiday lights in the park and then her initial refusal of a new set of lungs show that she is nearly willing to throw away what she has worked so hard for. However, a vision of Abby telling her to live and Will’s insistence convince Stella to accept the lungs. While she misses Will, she is forever changed by her time with him, and by the end of the novel, she embraces the ability to take on new experiences in life.