Who is Ruthie from Sybil and what is their importance?

Ruthie Dorsett is a little girl, only three years of age. Her appearance was a direct response to Willard and Hattie's sexual activity. Ruthie once tried to crawl between Hattie and Willard while they were making love, and she would tell them to go to sleep in an attempt to prevent them from having sex. Ruthie is not one of the more prominent selves.