Cover of "Killer's Kiss"
Sarah Easton is a minor villainess from "Killer's Kiss", book #42 of R.L. Stine's original Fear Street series (published on February 1, 1997). She was the younger sister of protagonist (and later revealed main villainess) Delia Easton, who she often fought with. In her first appearance of the book, she interrupted Delia's date with her boyfriend Vincent Milano and screamed at Delia that she hated her when she insulted her during their argument. She was later seen smirking as Delia's violin performance for a scholarship competition was ruined by presumed sabotage from her rival Karina Frye (though it was later revealed she'd done it herself to frame Karina).
It was later revealed that Sarah herself was also dating Vincent, who was seeing both Delia and Karina, and had helped Vincent in turning Karina and Delia against each other when they began to form a truce. When Delia caught the two together, the evil Sarah expressed no remorse for her actions. Delia then had Sarah leave to confront Vincent on her own--but not before telling Sarah that she would never be anything special, even dressed in Delia's clothes and makeup. This upset Sarah and sent her out of the room in tears.