Jo Harvelle means in slang: Supernatural’s super-**** female hunter. She lived with Ellen, her mom at the Roadhouse until Ellen decided she would like to hunt on her own. Her dad, William Anthony Harvelle gave her a knife. John Winchester was Jo’s father and Jo was friends. John shot Bill because a demon had attacked him. Ellen believes that John is responsible and doesn’t want Ellen to hunt with Dean. Jo thought hunting was glamorous and she was a bit childish the first time we met her. He likes Jo and she likes Dean, but he doesn’t want her hurt. Sam is possessed by Dean and he visits Jo to save her. The demon knows Dean loves Jo, and it won’t be easy for him to make a choice between Sam and Jo. Dean rescues Jo, and Jo then saves Dean from drowning. Her hunting is not over. Because they share the same history, Jo is the only girl Dean could have a relationship. (in Slang Dictionary, added by Benjamín Crespo)