Who is Carol from The Silver Kiss and what is their importance?

Carol is Anne Sutcliff's friend through the course of the book, whom we understand has been a friend to the family for many years. She is understood to be a kindly woman who meets Zoe at the hospital when her mother is ill and comforts her when Zoe is frozen and unable to go to her mothers aid.

Carol is presented as another element of the family dynamic who is nevertheless removed from Zoe and Harry's feelings of grief and loss. She acts more in this story as a plot device to examine the on going effects of Zoe's dislocation from her family.