Two months before Rafael went to the boarding school, they were going out with each other and when he thought she was flirting with another guy, they got into an argument in the car. Rafael had gotten angry and had taken the turn harder on the road while it was raining, and Cassie didn't survive.
In Death Keeps Knocking On My Door, she walks down the road in Mystic Falls to head to the Salvatore Boarding School for the Young & Gifted. She makes it up the stairs and sees Rafael, who goes to hug her. She then talks to both Alaric and Rafael, and she is told that she had died two months ago. She tries to call her mom, but Alaric advises her not to as it would hurt her. She then talks to Rafael again and reveals to him that she started to remember more of the accident and asked why he killed her. He gets angry with her and leaves her alone for a bit before checking on her again in the library. Outside by the lake, they both talk about his anger and the accident, and she tells him that she forgives him, telling him to leave her alone for a few minutes so she can stand out in the sun. It is also revealed that the Necromancer had been controlling her to find the knife and give it to a Bennett witch to unlock one of the three keys to Malivore, and then disappears, finding peace.
Cassie seemed to have the personality of a normal teenaged girl. Although she was fearful of the unknown around her when she first found out about the supernatural, Cassie remained calm given her situation. Cassie also tended to snoop around whenever she wanted to find information out. She also wanted those around her to be honest with her, particularly with her former boyfriend when she wanted to him to be honest with her about the reason she died.
She was young woman with a somewhat short stature and an athletic build. She had medium length black hair and dark brown eyes.