The Vampire Diaries, Season 4

Bonnie:
These symbols must have been left for the Hunters so they could find the cure. And this must be the story of Qetsiyah and Silas. According to Shane, Silas asked Qetsiyah for help making a spell for immortality. She helped make him immortal, only to learn he planned to use the same spell on another woman, not her. When she found out, she freaked.

Jeremy:
So, Qetsiyah kiled the other woman?

Bonnie:
Yeah. Silas was immortal. She couldn't kill him. So, she tapped him in a cave and buried him alive instead.

Jeremy:
Does it say anything about the Hunters purpose in all this?

Shane:
I was wondering when you'd ask. Qetsiyah created a cure for immortality and then she buried it with Silas, hoping that he'd take it and die. End up on the other side with her for all eternity. But he wouldn't give her the satisfaction. So, many centuries later, her descendants created the Hunters to find him, cure him, and kill him.