Tracy Bell is a hunter whose parents were killed by a demon.
When Lucifer was released from his cage, a demon killed Tracy's family to celebrate. Tracy later developed a hatred for Sam when she heard it was him killing Lilith that released him. Tracy became a hunter and one time teamed up with Irv Franklin to kill a shapeshifter in Sacramento.
She was first seen killing a vampire in a truck and getting kidnapped by Abaddon's demons. She and Irv were rescued by Sam and Dean Winchester. Sam and Dean split up and she went with Dean who convinced her of Sam's good nature despite his mistakes. They encountered Abaddon and Tracy shoots Abaddon full of Devil's trap bullets, but they were rendered useless as Abaddon was wearing a bullet proof vest. Dean splashed holy water on the demon and told Tracy to go get his car. She then drove the car and fetched the Winchesters to escape after Abaddon had disappeared. Before getting into the car at the end, she asked Sam if he was alright and when he responded affirmatively, she replied good, signifying to him that she has forgiven him.
Later in the Bunker, Sam reveals that he is apologetic and guilty for what happened to her family.