Who is Catherine's Father from Many Lives, Many Masters and what is their importance?

Catherine's father appears in several of her past lives. He is never a pleasant character. In this life, he molests her while drunk when she is only three. Past lives and dreams reveal that Catherine's soul reincarnates often with her current father's soul. According to the premise of the book, their souls owe debts to one another and have lessons to learn together or from each other. Weiss' extrapolates that Catherine is meant to teach her father, who just doesn't want to learn. He is an alcoholic, who has little belief and treats people like objects.