Jennifer Blake is the english teacher of Beacon Hills High School and is also the amor interest of Derek Hale she was revealed as the Darach who is a serial killer that kills virgins, healers, guardians and etc, as a manner known as the threefold death. and Lydia Martin who is the sometimes troubled best friend of Allison Argent who was revealed as a Banshee who has the ability to know when someone dies or is about to die. Jennifer was the one who killed the chemistry teacher Mr. Harris and Lydia was screaming out through out the series. Now you have it people Jennifer as the Darach and Lydia as the Banshee/ The Wailing Woman.