Caroline
A homeless girl who was abducted from her childhood home, either by her father or by a man claiming to be her father. In either case, she is raised in isolation in a cave outside Portland, but they return to the city weekly for supplies. Eventually, they are discovered, launching Caroline into her own vagrancy.
Caroline's "Father"
Later in the novel, the reader learns how Caroline met her "father" and the situation is quite dubious. Caroline was a young child when this man showed up at her house in Boise, Idaho and told her that the family she was raised by was not her real family, that he was her real family, and that she should come with him. In other words, Caroline was abducted by this kidnapper who might be her father, but probably isn't.
Miss Jean Bauer
A helpful social worker who decides that Caroline should continue living with her 'father.' She reaches this conclusion partly because Caroline is incredibly well educated for her age, which is startling since she was literally raised in the wild.