Who is Hetty Sorrel from Adam Bede and what is their importance?

Hetty Sorrel is the pretty, vain and headstrong, young woman, who stays with her relatives the Poysers in Hayslope, Because of a somewhat deprived childhood, Hetty is vulnerable to the charms of Arthur Donnithorne, the callow aristocrat who breezes into town on a fishing expedition and stays long enough to play with her affections and get her pregnant without really caring about her. Hetty uses her attractiveness to get her way. She is a manipulator rather than an achiever and, because of her youth, a victim who is used by the older Arthur Donnithorne. Hetty is ruled by passion and self-interest, not unlike Arthur. Although the death of her infant is sad, the reader gets the impression she really cares more about losing Arthur than losing her child.