Who is Gillian Duncan from Salem Falls and what is their importance?

Gillian Duncan is the seventeen-year-old daughter of the richest man in town, Amos Duncan, who owns Duncan Pharmaceuticals. She is involved in Wicca with her friends Whitney O'Neill, Meg Saxton, and Chelsea Abrams. She frequently tries to call the spirit of her mother, who died when she was younger. Gillian and her friends spend a night in the woods celebrating Beltane. Gillian puts atropine, a hallucinogenic, in iced tea that the girls drink. Jack St. Bride stumbles onto the party. Gillian later accuses him of raping her to cover up the girl's involvement in witchcraft, although he did not do it. At the trial, Gillian's lies are uncovered and Jack is freed. Amos and Gillian are revealed as having an incestuous relationship at the end of the novel.