Cassie Newton the daughter of a divorced couple. Her mother obtained custody, while her father only obtained one weekend a month with his daughter. Cassie meets Buffy Summers, Sunnydale High's guidance counsillor and reveals she will die on the next Friday. Buffy, along with Xander, Dawn and Willow, manages to save her from a group of boys who try to sacrifice her to the demon Avilas. However, immediately after, Cassie dies of a heart failure caused by a congenital condition, fulfilling her own prophecy.
- Buffy: “See? You can make a difference.”
- Cassie: “And you will.”
- — Buffy and Cassie's final conversation[src]
Before dying, Cassie reveals a couple of prophecies that are fulfilled during the battle between the Slayers and the First's Turok-Han army. She reveals to Spike that "[Buffy]'ll tell [him]" she loved him and to Buffy that she would make a difference: transforming every potential Slayer in the world into real Slayers.
- “She asked that I come talk to you. It's important.”
- ―Cassie's "ghost"[src]
Cassie then appears to Willow in "Conversations with Dead People" and tells her that she had a message from Tara; that if she uses magic, she will kill all her friends. Willow believes her until Cassie tells her that she should kill herself to save everyone and be with Tara again. Willow then realizes that this "girl" is not Cassie. After being discovered, "Cassie" (who is actually a disguise of The First Evil) taunts Willow and dissappears.