Bobby became a hunter after he had to kill his wife Karen Singer when she was possessed by a demon. Rufus Turner is the hunter who exorcised the demon and helped cover up Karen's death. It was Rufus who introduced Bobby to the world of the supernatural, and they hunted together for many years until a hunt went wrong in Omaha around 1993. They become estranged after this although they had contact and some reconciliation from 2008 until Rufus' death in 2011.
Bobby's guilt over Karen's death causes her to inhabit his dreams. She is later resurrected by Death and turns into a zombie and he has to kill her again, which causes him more grief.
Bobby has known the Winchesters since at least 1991 - he gave an eight year old Sam an amulet as a Xmas present for his father, which he eventually gave to Dean. John Winchester and Bobby were not necessarily on good terms - Dean comments that the last time Bobby saw John he nearly "filled him with buckshot". It is to Bobby's place that Sam and Dean go to grieve after John's death. After this Bobby's relationship with the Winchesters grows even closer, and he becomes both father figure and friend.
When Sam and Dean try to go after Lilith without him, Bobby tells them "Family don't end with blood, boy." and more than once Dean tells Bobby he's like a father to him. Bobby has listed Dean as his official next of kin. In 2009, Bobby is paralyzed from the waist down after stabbing himself with Ruby's Knife to overcome his own demonic possession when Meg orders him to kill Dean.
Bobby sells his soul to Crowley in exchange for information on Death's location. Crowley also makes it possible for Bobby to walk again. He says that he will return Bobby's soul after Lucifer is defeated. It is later revealed that Bobby was given the standard ten years to live until his soul is dragged to hell. Bobby is able to trick Crowley and negotiate the return of his soul.
Sam visits Bobby on his release from Lucifer's Cage, and Bobby agrees to keep Sam's return a secret from Dean, who Bobby sees at having a chance at a normal life. Following his reunion with Sam, Dean (worried because of Sam's cold and relentless behavior) calls on Bobby for support.
A soulless Sam later turns their closeness against Bobby when Balthazar tells Sam that the spell to keep his soul from being returned requires the blood of his father but that needn't come from the "father of your blood", and he tries to kill Bobby. Following the return of Sam's soul, Bobby finds it initially difficult to be around Sam because of this assault.
Bobby continued to work with Sam and Dean hunting the Mother of Monsters - Eve. While possessed by a creature she created, he kills his old friend Rufus Turner.
Bobby is the first one to voice concerns about Castiel's activities, and is with Sam and dean when Godstiel appears.
Life and habits
Since the death of his wife Karen Singer, the only other romantic interest in Bobby's life that we've met is Eleanor Visyak. His neighbor Marcy Ward expresses an interest in him, but a messy incident with an Okami ends any possibility of a relationship.
Bobby has extensive knowledge of the supernatural, and is well-known and generally well-regarded by other Hunters such as Gordon Walker, Kubrick, Rufus Turner, Olivia Lowry, Isaac and Tamara among others. He also knows Ellen and Jo Harvelle. According to Jo's Journal, Bobby frequented the Roadhouse from around 1993.
Bobby's reputation around Sioux Falls is that of a troublesome old drunk, but following his role in quashing a zombie uprising, the local sheriff, Sheriff Mills, comes to develop a friendship with him.
Bobby reads and speaks Japanese and has visited Japan.
Bobby is often seen with a Colt Single Action Army revolver, presumably chambered in the .45 Colt caliber.
Favorite expletives are Idjit - usually in relation to Sam and Dean - and Balls! He is known to like pedicures and enjoy watching the reality show Tori & Dean.
Bobby owns Singer Salvage Yard (also seen written as Singer Auto Self Service Salvage Yard, on a sign in Everybody Loves a Clown), and lives in a house on the premises. It is located in South Dakota (as confirmed by Dean in 2.14 Born Under a Bad Sign), near the town of Sioux Falls.
Bobby has lived at Singer Salvage Yard since he was married to Karen. It is here the Impala is towed after she is wrecked, and where Dean repairs her.
Bobby's house contains many esoteric books on lore and religion. Bobby has a wall of at least five cordless phones in the kitchen, each labeled with a different government agency and alias. When a hunter is pretending to work for the FBI or other agency, they give a number to one of the phones and Bobby answers as their superior.
The basement is an unfinished storage space except for a large ghost and demon proof panic room, which Bobby built on “a weekend off.” Over time, Bobby has made other modifications to the house. Sometime after 5.15 Dead Men Don't Wear Plaid, Bobby placed a trap door in front of the hall closet that can be triggered by a lever inside the closet. The trap door opens into the basement, which he equipped with a steel core door and titanium kick plate.
He had a dog called Rumsfeld who was killed by Meg.
Bobby owns a blue Ford tow-truck with Lawrence County, South Dakota plates : 9NO3L1. This is probably a reference to Jim Beaver's role in the HBO Western drama Deadwood. Deadwood is the county seat of Lawrence County. In Season Three he also drives a 1971 Chevelle.
Bobby gets people to drink holy water to test whether they are possessed - he first does this to Dean when he and Sam are trying to find where Meg is holding their father. He gives Sam beer laced with it when Sam is possessed and Ellen has to drink a holy water shot after she escapes the demon attack on the Roadhouse. When Dean returns from the dead in 4.01 Lazarus Rising, Bobby throws holy water in his face, even though Dean has cut himself with a silver blade to show he is human.