The narration returns to first person. Aza tells the reader that after she descended into "proper madness," she solved the mystery of Davis Pickett Sr.'s disappearance, using her obsessiveness and becoming a great detective in the process. She walks into the sunset with either Davis or Daisy and realizes she has control over her thoughts.
Aza challenges the idea that illness is only real when others can see it (like when she's compulsively drinking hand sanitizer). Of course, Aza knows this isn’t true—she was ill long before she started consuming hand sanitizer.
Aza says that that definitely didn't happen. She stayed in bed in the hospital for a week, and the hospital staff thought she was an alcoholic until they got in contact with Dr. Singh. When Dr. Singh arrives, she sits next to Aza and they talk about Aza's medication. Aza admits that she felt the medication was making her worse, and Dr. Singh explains that drinking hand sanitizer isn't a sign that Aza's mental health is improving, as hand sanitizer is extremely dangerous to ingest. She says they need to find a medication that Aza will tolerate and take regularly, and says they haven't found one that works yet.
Medications like those prescribed for anxiety differ from something like hand sanitizer in that they don't always "work" in the way that hand sanitizer does—they're not a one-size-fits-all solution. With Aza's intense fear of bacteria, this makes something like hand sanitizer seem far more reliable, as it's easier to attack the bacteria directly than it is to trust that the medication is calming her anxiety about the bacteria.
Dr. Singh comes every morning and a doctor checks on Aza's liver every afternoon. On Aza's last day, Dr. Singh asks Aza if she thinks she's a threat to herself. Aza admits that she's having intrusive thoughts, but is honest that she hasn't consumed hand sanitizer. Dr. Singh tells Aza that she doesn't have to be afraid of thinking about wanting to drink hand sanitizer, and tells her that only time and taking medication will help. Aza says it feels like a noose is tightening around her and struggling makes it worse. Dr. Singh tells Aza that she's going to survive.
Dr. Singh confirms one of the primary underlying messages of the novel: that mental illness isn't something that Aza will "recover" from in a conventional sense. She'll have to continue to take medication and attend therapy in order to manage her thoughts, but if she does, she'll learn to control some of the intrusive thoughts that threaten to split her identity in two or more parts.
Dr. Singh comes to Aza's house twice per week. Mom makes sure that Aza takes her medication, and Aza isn't allowed to get out of bed except to use the bathroom. This continues for two weeks. Aza doesn't allow Daisy or Davis to visit, and doesn't read or watch TV. She keeps her phone off until the end of the two weeks, at which point she turns it on and finds over 30 messages from Daisy, Davis, other friends, and teachers.
Aza takes this time to simply be with herself and her selves. Although Aza never states what medication she is on, it's likely a drug that takes several weeks to begin taking effect. By the end of these two weeks, during which she's taking the pills regularly, Aza is therefore likely beginning to benefit from the effects of the medication.
Aza returns to school in December. She says that she isn't wondering whether or not to take her medication, but isn't sure yet that it's working. Mom drives Aza to school since Aza is too scared to drive and Harold is totaled. Mom assures Aza that her friends and teachers will understand.
Aza's fear of driving shows that her anxiety certainly isn't gone now that she's taking her medication as prescribed. She'll still experience it, it just won't be as crippling or as destructive as it was in the hospital.
Daisy waits for Aza on the front steps. Aza notices that she got a haircut as Daisy asks if they can hug without hurting Aza's liver. Aza compliments the haircut, which Daisy deems a disaster. Aza and Daisy both apologize to each other, and Daisy says that Aza has to read her new fanfiction, which is an apology. She continues by saying that Aza is exhausting but endlessly fascinating, and is pizza, not mustard.
Aza is expanding her spiral by noticing and commenting on Daisy's haircut. She has room in her mind now to involve more people and think about them and how they feel. Daisy's language suggests that she's returning to situating her identity in relation to Aza, and possibly not to Mychal.
Aza tries to apologize again, but Daisy cuts her off. She insists that she wants to be buried next to Aza, and asks Aza if she should keep talking. Aza nods. Daisy explains that she and Mychal broke up, she sold her car, and Elena put gum in her hair, which necessitated the haircut. She says she plans to take Uber everywhere now and asks Aza if she should keep going. Aza nods again, and Daisy says that this is why they're destined to be friends forever. She says that after Elena put gum in her hair, she paid for the haircut out of the college fund her parents made her set up for Elena.
Even if Daisy finds Aza unbearable at times, the girls complement each other: Daisy talks, Aza listens. Essentially, the way they use language with each other matches up and allows them to both understand and appreciate each other. When Daisy's parents make her set up a college fund for Elena, they force her to see another's need and do something nice to help make the need easier to bear.
Daisy says that the breakup with Mychal made the lunch table awkward, so they're going to picnic outside today. She tells Aza that a lot has happened since Aza lost her mind. Aza corrects her that she can't lose her mind, since it's inescapable. Daisy responds that she feels that way about her virginity, which is the other reason she broke up with Mychal. Daisy walks Aza to Biology and tells her that she used to think she was in a romance movie, but realizes now she was in a buddy comedy.
Daisy realizes now, at the end of the novel, that she was moving through life as though it were a different kind of story than it actually is. Daisy's comment about being in a “buddy comedy” asks the reader to take the novel as more of an exploration of the girls' friendship than an exploration of Aza's relationship to Davis—though of course it can be both.
At lunch, Aza and Daisy sit outside eating leftover pizza. Daisy says she's been thinking a lot about how Mr. Pickett left his kids without saying goodbye, and feels bad for him. Aza thinks that she feels bad for Noah, who wonders if his father will call and then plays video games to distract himself from the fact that he didn't call. Aza thinks how horrible it must be to know that your father privileged a tuatara over you.
Daisy feels bad for someone behaving cruelly and selfishly, while Aza feels bad for someone who doesn't have knowledge or closure. Eating pizza here is a nod back to Daisy's assertion that Aza is like pizza. Notably, in this case, Aza isn't bothered by eating something that symbolizes her self—a sign that she may be getting better.
Aza asks what Daisy's parents do. Daisy laughs. Her dad works at the State Museum, and her mom works at a dry cleaners. Daisy explains that her parents weren't at all mad about the money from Davis, and made her set up the college fund for Elena. Aza feels her finger bleeding and knows she'll have to change her Band-Aid before class, but likes sitting next to Daisy for now.
Finally, Aza expands her spiral to include Daisy's family by asking these questions that Daisy insisted Aza didn't know about. Readers are given proof that Aza's anxiety is more controlled now when she doesn't feel the compulsion to go change her Band-Aid immediately.
Daisy asks about Davis, but Aza hasn't talked to him or anyone else. Daisy asks Aza if she thought about killing herself. Aza says she's only thought about not wanting to be the way she is. She says she feels non-navigable, like the White River. Daisy insists that the point of the story of how Indianapolis was built is that people managed to build a decent city around a useless river. She says that Aza is the city, not the river. Aza laughs. Both girls lie down and look up through the branches of the oak tree at the sky.
Aza suggests that she didn't want death specifically—she just wanted peace and escape. She finds her self to be unknowable and undiscoverable, since her "waterways" are difficult to get through. Daisy's comment that Aza is the city and not the river suggests that if Aza continues treatment, she will become something wonderful despite her difficult waterways.
Daisy says she wishes she understood how Aza feels. Aza explains that she doesn't hate herself, because she can't find a self to hate. She says that her mind is like nesting dolls, but she never finds the solid nesting doll that's her self in the middle. Daisy tells Aza the story of a scientist who gives a presentation about the history of the earth. At the end of the talk, a woman stands up and informs the scientist that the world is actually flat and resting on the back of a turtle. The scientist asks what the turtle is standing on. The woman says it's standing on another turtle, and that there's no end: it's turtles all the way down. Daisy suggests that Aza is trying to find the turtle at the bottom, but it doesn't work that way. Aza feels like this is a spiritual revelation.
Even now, Aza still sees herself as being made up of multiple identities, though not all of those identities are visible (as evidenced by the solid nesting doll metaphor). Daisy's story suggests that Aza is an uncountable number of identities, and further, that trying to count them is a futile exercise. For her, simply realizing that there maybe is no "clean self" or solid nesting doll allows her to become comfortable with the chaos inside her mind. This mirrors Malik's statement about science: it just makes more questions, which isn't a bad thing.
Aza stops at Mom's classroom after lunch and tells her about the money from Davis. She says she's saving it for college. Mom says that much money isn't a gift and that Aza should give it back. Aza says that the money didn't make her sick and that she doesn't feel indebted to Davis. Mom starts to say that she can't lose Aza, but Aza interrupts and asks Mom to stop saying that. She says it makes her feel like she's actively doing something to hurt Mom and it makes her feel worse. Mom says that she is losing Aza, but agrees that Aza should be able to make her own choices. Aza thinks of the way she loves Mom, in a mental refrain of "thank you I'm sorry."
Mom begins to understand that her desire to protect and hold onto Aza is somewhat responsible for exacerbating Aza's anxiety, as Aza feels pressure to behave and think in a way that will make Mom happy and comfortable. By conceding that Aza should be able to make her own decisions, she allows Aza to begin to solidify her identity and move ahead in the world. This symbolizes a split in the mother-child relationship, but a solidifying of Aza's identity.
Mychal catches Aza on her way to History and asks her to talk to Daisy about the breakup for him. Aza flags down Daisy and tells her and Mychal to talk to each other about their relationship. A few minutes later, Daisy texts Aza and says that she and Mychal are now friends who kiss. Aza texts Davis and apologizes for not texting him. They agree to meet that night at Applebee's.
When Daisy uses her own words, she gets what she wants out of her relationship with Mychal. This also shows Aza rejecting a role that Mychal would like to impose on her—that of a messenger. In turn, Aza is able to further solidify what she wants her own identity to be.