Due to the father-son dynamics of the hunting world depicted in the series' first season with the Winchesters, the writers decided to explore a mother-daughter relationship, resulting in the introduction of Ellen and her daughter Jo. The name originated from the writers' decision to base her on the "tough yet emotionally-vulnerable" characters portrayed by actress Ellen Barkin. Ellen was meant to have a "true and honest platonic friendship" with John Winchester, and her backstory of her husband having been killed due to John's mistake was added to the storyline to explain why John never mentioned the Roadhouse to his sons. Ferris auditioned for the role, and feels that she was exactly what they had been looking for. She commented, "I have a certain kind of personality that works specifically with a role, and Ellen is just me on television. They were looking for a tough, strong, yet a little maternal actor, and I struck a chord." Series creator Eric Kripke agrees, feeling that Ferris "really brought the character to life," being "nuanced and complex and tough, yet beautiful and feminine."