In the final segment of this book, it parallels by rewinding back to Davids childhood in the form of a dream. He is afraid of the outside world and in the dream he is the only resident in his home. I feel this is a reflection on the feeling of loneliness he felt as a child due to the distance between him and his family members along with the lack of healthy communication between the members of his family.
In his dream, he sees his mother sweeping a path for him to the insane asylum where his grandmother is. This is intended to be his fate in the way he feels others see it but he makes the choice not to follow this path. This brings up the whole concept of fate vs. free will. David has been thrown enough obstacles to the point where if he were to go down this path it would not be surprising or inappropriate in many peoples eyes. His mother doesn't love him, he was like a lab rat during his childhood, he had cancer, he lost his ability to speak and he had a dysfunctional relationship with the members of his family. But much like Oedipus, he choses the path he wants to go down, and in this case it means not letting his environment and circumstances he grew up with define him as a person.