Sharon is a patient at the Rothman Rehabilitation Home for Feral Children. Although an adult now, she survived the Great Panic and subsequent zombie wars as only a wee child.
Sharon's story really serves two purposes for us. First, its World War Z's only story from the perspective of a child. Due to Sharon's fracture psyche, she tells her story from the point of view of her childhood self rather than that of an adult looking back on events.
The effect of naïveté and innocence relating such a horrific tale is truly stunning, and it helps us come to grips with how awful the experience must have been. Since most of the tales are told after the fact, the rationale of hindsight is put upon the telling. But with Sharon's story, you feel the terror of being in the thick of it.
Second, Sharon's story shows us just how psychologically traumatizing such a disaster can be on people—whether it is the fictional zombies or very real disasters like plague or war. Once again, Sharon tells her tale as if she were there, complete with sound effects that would make Michael Winslow proud.
The other characters have basically been able to come to terms with what happened (except Redeker, maybe). But Sharon has been forever psychologically scarred. Since the event happened while she was still a child, she can't process and rationalize the horrors like the others can. This is particularly evident when she explains her mother's death as: "Warm and wet, salty in my mouth, stinging my eyes" (4.3.17).