Cassidy's mother died when she was young. Her father Dan struggled to raise her by himself, eventually directing his anger over no one willing to help them toward the minorities, specifically the Jalalzai family, causing him to neglect her. This resulted in her disliking him, and eventually becoming promiscuous.
Cassidy was promiscuous, sleeping with many men, and enjoying it. She also disliked her father due to his emotional neglect of her.
Despite this, she appeared to have some of her father's beliefs, to the point of accusing Saadia's family of having killed Frank Dixon. However, it is unknown if she actually had her father's racist beliefs or if she hated Saadia because she knew that Saadia's family arriving was the reason her father began to neglect her.
Cassidy was killed by the Druid who used hydrochloric acid to heavily disfigure her, eventually she succumbed to the Druid's justice.