Who is Marie from Crank and what is their importance?

Marie is Scott's wife and mother to Leigh, Kristina and Jake. Although Kristina remembers being close to her mother as a young child, they no longer have this close relationship. Her mother has remarried, and has another child by this second marriage. Both of these people take her mother's attention away from Kristina. In addition, Kristina's mother is trying to write a book in order to win her some sort of late in life fame. This attempt to write a book also takes time away from Kristina. Kristina's mother does not want her to go visit her father. However, Kristina convinces her mother she can take care of herself. When Kristina returns from Albuquerque, her relationship with her mother is not the same. Kristina's mother begins to worry about her daughter when she first returns from her visit to her father, but is not able to determine for sure what is wrong.