In my opinion, one of the first indications that the family is using isolation to cope manifests itself in their isolation from Susie's room:
Already my private territory had become a no man's land in the middle of our house. My mother had not touched it. My bed was still unmade from the hurried morning of my death. (44)
All three use isolation as a coping mechanism in slightly different ways. Let's explore the three characters in turn.
First, we'll begin with Lindsey, Susie's sister. Lindsey first deals with Susie's death by isolating herself from anyone who could help her at school, such as Principal Caden. After confronted with the compassion of his "I'm sorry to hear of your loss" statement, Lindsey hits him with "What exactly is my loss?" (31). Also, Lindsey seeks solace in private, small rooms of the house, like the bathroom shower.
She would be safe in the dark--the moist steam from the shower still rising off the tiles encased her. . . . She knew she would be undisturbed. (59)
Probably the best quote and best example of Lindsey's isolation is when she actually vocalizes her issue in a brief dialogue with her father:
"Lindsey, can I come in?"
"Go away," came her resolute answer.
"Come on now, honey," he pleaded.
"Go away!" . . . "Look, Dad," my sister said, making her one concession for him, "I'm handling this alone." (60-61)
Sebold clinches Lindsey's isolation by stating the obvious: "[Lindsey] was working hard keeping everyone out, everyone, but she found Samuel Heckler cute" (67). And, of course, it is Samuel who succeeds in bringing Lindsey out of her isolation.
Second, we must deal with Susie's parents who Sebold accurately describes this way: "In those first two months my mother and father moved in opposite directions from each other" (86). This gives us a perfect look at their isolation, even within the context of their marriage.
Jack plunges himself into isolation amid all of the ships-in-bottles that both he and Susie had made together: their special project that is now in ruins.
He christened the walls and wooden chair with the news of my death, and afterward he stood in the guest room/den surrounded by green glass. The bottles, all of them, lay broken on the floor, the sails and boat bodies strewn among them. He stood in the wreckage. (46)
A bit later, guilt seeps into Jack like "poison" and "at first he couldn't even get up" (58).
Abigail's progression into isolation gets worse as the novel wears on. It is interesting as a reader gets her first simple glimpses:
Before my father left for Mr. Harvey's, my mother had been sitting in the front hall next to the statue they'd bought of St. Francis. She was gone when he came back. (59)
First Abigail simply appears and disappears in different places, . . . or simply focuses on washing dishes in the sink instead of anything else. Later, her thoughts reveal the beginnings of her isolation from her other children, such as when Buckley simply calls to her:
"Momma?" Buckley repeated. His voice was sleepy.
She despised the word. (62)
Suddenly, Abigail's silent isolation ceases, and she becomes more aggressive:
My father watched as my mother froze, then burst, fleeing to their bedroom to wail behind the door. (86)
And, of course, Abigail's isolation only gets worse before it gets better.