Fire symbolizes the relationships within the Fitzgerald family, evidenced in part by Picoult’s choice of Carl Sandburg’s poem “Kin” as the epigraph for the opening chapters. The poem describes fire’s ability to warm as well as to consume, just as the relationships we see in the family, particularly that of Anna and Kate, can both nourish and destroy. Anna and Kate emotionally sustain each other, for instance, even as Anna undergoes painful medical procedures in order for Kate to survive. At the same time, Kate feels increasingly wasted and consumed by her struggle to remain alive, and to a great degree no longer wants to be sustained. Moreover, Anna compares her decision to file the lawsuit for medical emancipation with giving fuel to a fire. Another of the epigraphs Picoult chooses, the poem “First Fig” by Edna St. Vincent Millay, talks about a candle burning at both ends. The family, like that candle, is metaphorically burning itself out.
More than any of the other characters, Jesse and Brian display particular preoccupations with fire. Jesse turns out to be the arsonist setting fires all over the city, while Brian, a career firefighter, earns his living putting fires out. Although Jesse and Brian approach fire in different ways, fire means essentially the same thing to both of them. They view it as a destructive and essentially uncontrollable force, and in that sense fire to them serves as a symbol of Kate’s cancer and the effect that cancer is having on their family, which is figuratively burning out. Just as Brian puts out actual fires at work, he tries at home to put out figurative fires, such as the emotional problems Anna has in response to Kate’s health and Jesse’s negative behavior in reaction to Kate. Jesse’s destructive acts, notably his setting fire to several buildings, stem from his overwhelming sense of guilt over his inability to save Kate. His feeling of powerlessness regarding Kate’s cancer turns into rage, which he releases by burning down buildings. For Jesse, fire also serves as a way to gain his father’s attention, albeit indirectly. Jesse feels neglected because his parents focus so much on Kate, but by setting fires he can literally call his father’s attention any time he chooses.
Stars and dark matter function as separate, but related, symbols in the novel. Because stars emit light, we can see where they are and how they move. But dark matter, as Brian explains to Julia, can’t be seen. We only know it exists because we can measure the gravitational effect it has on the visible objects, including stars, around it. Similarly, the references to stars in the novel, which come predominantly from Brian, relate to the general situations characters find themselves in. When Brian talks about twin stars, for instance, and how the light from one star can be so bright that it obscures the light of the other star, the metaphor clearly points to the relationship between Anna and Kate. Because her illness draws so much of their parents’ attention, Kate figuratively obscures Anna’s presence. In another example, we learn that Brian and Sara named Anna after the constellation (and galaxy) Andromeda, said to be located in the sky between her mother and father. Anna, similarly, has one parent on either side of her in her court battle, with one supporting her decision and one fighting it. Furthermore, in Greek mythology, Andromeda’s parents sacrificed her to save their country, much as Anna’s parents force Anna to make sacrifices to save Kate, and to a large degree, their family.
Dark matter, on the other hand, refers to the hidden motivations influencing the behavior of the characters. For Anna, that motivation is her desire to fulfill Kate’s wish to die, which prompts Anna to file the lawsuit at the center of the novel. For Jesse, the metaphor pertains to his feelings of guilt over not being able to save Kate and his desire for more attention from his parents, both of which lead him to start setting fires. For Campbell, the wish to hide his epilepsy motivates him, causing him to lie about his need for a service dog and providing the reason he ended his relationship with Julia when they were younger. In each case, the characters try to keep their motivations hidden, but those motivations still show themselves in the behavior of the characters, just as an observer can detect the presence of dark matter by its effects on its surroundings.
More than her baldness or the scarring on her skin, Kate’s central line, meaning the catheter protruding from her chest that serves as the main port into Kate’s body for her treatments, symbolizes her cancer. Repeatedly in the novel, characters note the presence of Kate’s central line. For instance, when Kate receives her first dose of cord blood, harvested from Anna’s umbilical cord just moments after her birth, Sara watches the doctors connect the bag to the central line. The most notable episode involving Kate’s central line occurs when Kate, Anna, and Sara shop for Kate’s prom dress. Kate becomes frustrated because the dresses are cut too low. When the saleswoman, thinking Kate’s concern is that she doesn’t want to show too much skin, suggests a dress that will cover what she calls “a fair amount of cleavage,” Kate becomes angry. Kate opens the top of her blouse revealing the catheter sticking out from her chest and asks the saleswoman if the dress will cover it.