The next day, Mom finally gives in to Susannah's pleading and allows her to return to her apartment, as long as she agrees to spend a night with Dad. Susannah agrees and happily leaps into Dad and Giselle's car. At her apartment, Dad is repulsed by the smell. Susannah hadn't cleaned the apartment since his last visit. He and Giselle clean the apartment as Susannah watches.
The state of Susannah's apartment is clear evidence that she's unwell and unable to actually live up to the adulthood symbolized by the apartment itself. Her lack of shame or emotion about its state then reinforces this. Her illness is causing her to disregard all social customs.
When they're finished, Giselle heads downstairs and Susannah tries to talk Dad into letting her stay in the apartment alone. Dad finally convinces her to come with him. They chat pleasantly as they walk through the city, but Susannah soon becomes paranoid that Dad took her keys. In the middle of a busy street, Susannah stops and begins shouting. Dad pulls her out of the way of oncoming traffic and bundles her into a cab with Giselle. Susannah attempts to tell the driver that Dad and Giselle are kidnapping her, but Dad instructs the driver to drive. When Susannah threatens to call the police, Dad snaps at her but then softly asks why she's doing this. Susannah admits to the reader that she had no idea, but knew she wasn't safe.
Susannah's insistence on independence is one character trait that carries through both her "real" self and her ill self, which shows that though her illness is exacerbating and twisting it, the trait itself is strong enough to override the illness. Her paranoia about not having access to her apartment (and therefore, freedom and independence) reinforces how intensely important this is to her.
When they finally arrive in Brooklyn, Susannah is exhausted. Giselle and Dad cook while Susannah lounges on a couch. When Dad and Giselle call Susannah for dinner, she can only watch them eat because the colors of the food look unnatural. Afterwards, Susannah hears Giselle say, "you're a spoiled brat." Susannah calls Giselle out, but Giselle only seems surprised.
By making it clear that what Giselle "said" is a hallucination, Cahalan allows the reader to share Giselle's shock and alarm at Susannah's aggression. In doing so, Cahalan asks the reader to identify with these family members who are at the whim of a person they barely recognize.
Susannah asks Dad to spend the night with her in the den. They talk for a while, and Susannah admits that she's scared. Minutes later, she yells at Dad to leave. This goes on for hours. Susannah tells the reader that neither she nor Dad remember much of that night, but she said something horrible enough to make Dad cry.
By asserting her right to keep some things private, Cahalan insists that the particulars of what she said aren't necessarily important to understand her illness. The important part is that she said them, and they're out of character, and they deeply upset Dad.
After banishing Dad, Susannah hears a pounding from upstairs. She ignores it, but soon hears Giselle pleading with Dad to not hurt her. Susannah realizes that Dad is beating Giselle because he's upset with her. Frantically, Susannah wonders if Dad is going to kill her next. She screams for someone to let her out and locks herself in the bathroom. Just as Susannah prepares to jump out the window, she notices a Buddha figurine and realizes that everything is going to be fine.
Susannah's sudden shifts in mood show that the sick Susannah isn't at all logical, reasonable, or any adjective that could have described the "real" Susannah. Cahalan presents this hallucination as fact from the viewpoint of the sick Susannah to illustrate how her grip on reality is entirely gone as her brain fights her illness.