The character, a "rough but warmhearted" working-class man who hunts supernatural creatures, has evolved over time into a father figure for series protagonists Sam and Dean Winchester.
At times, Bobby defied John's wishes to teach the boys more mundane, normal activities, such as playing catch, so that they could have a break from the intensive training regimen.
While John eventually distanced himself from other hunters or fell out of contact with them, notably Ellen Harvelle and Daniel Elkins, he maintained a professional relationship with Bobby.
The Winchesters save Bobby's life when he is put into a coma by a teenager using dreamroot to enter the minds of others, but this results in Bela Talbot—a thief who takes supernatural artifacts that the brothers called for help finding the dreamroot—stealing the Colt while they are unconscious.
[8] When Dean mysteriously returns to life four months later in the fourth season premiere "Lazarus Rising", Bobby at first believes him to be a demon or some other type of supernatural creature.
While Sam later sneaks away to secretly hone his new-found demonic abilities, Bobby and Dean perform a ritual to summon whatever creature resurrected him.
When the brothers come across a poker-playing witch in "The Curious Case of Dean Winchester", he sees it as a chance to regain his mobility and wagers 25 years of his lifespan.
[15] In "Dead Men Don't Wear Plaid", Bobby's wife suddenly rises from her grave and appears to be completely normal, along with numerous other people buried at the local cemetery, all to their respective houses.
Still in need of Death's ring, Bobby sells his soul to Crowley—a powerful demon who also wants to stop Lucifer—in exchange for the knowledge of the final Horseman's location.
After a time-travel mission results in the brothers and Bobby acquiring the phoenix ash needed to kill Eve, they eliminate her in "Mommy Dearest".
They also realize that Castiel has been deceiving them and in "The Man Who Would Be King" deduce that he has collaborating with Crowley to open Purgatory in an attempt to acquire the power of the souls within it to use in the civil war in Heaven.
Despite their best efforts, Dean, Sam and Bobby fail to stop Castiel, who uses the Purgatory souls to elevate himself to a god-like level in the sixth season finale.
Although he initially helps the Winchesters in Season 7 in their struggle against the Leviathans—God's original creations, trapped for millennia in Purgatory until they were unintentionally released by Castiel—despite the destruction of his house, even determining their new foes' vulnerability to the chemical Borax, Bobby is eventually shot in the head by Dick Roman in "How to Win Friends and Influence Monsters".
Despite efforts to save him, Bobby flatlines from his injuries; his last word being "idjits" (sic, idiots) to Sam and Dean after passing on a sequence of numbers.
It's indicated that he stayed as a ghost to help the boys as there have been times since his death when the information they need inexplicably makes itself known to them, but they were initially unable to confirm or deny Bobby's possible presence.
At the end of the episode, Bobby's spirit can be seen in the brother's motel room, and he is annoyed when Dean comes in, looks right at him, and does not see him, instead grabbing his flask.
In "Of Grave Importance", the audience is fully aware of Bobby's ghostly existence and the episode revolves around his own parallel investigation with the Winchesters of a haunted house.
In the midst of his explanation, the brothers receive an email from a dead Frank Devereaux, who informs them that his hard drive, in Roman's possession at his headquarters, is currently being cybernetically attacked and will lead to their new aliases and safe houses being compromised.
While Bobby attempts to convince the Winchesters to send in his flask, the brothers are concerned his hatred for Roman will compromise the operation and leave him out.
While the operation is successful—wiping the hard drive, hacking Roman's email account and intercepting an important package—Charlene is unable to escape the building in time.
Bobby becomes increasingly frustrated in "There Will Be Blood", which only feeds his fast-growing rage and turns him more into a vengeful spirit, culminating in his possession of a maid, whom he uses to go seek vengeance on Dick.
However, the angel Naomi intervenes, drives Crowley off, and allows Bobby to ascend to his rightful place in Heaven, thus completing the second trial.
Bobby explains the history of Apocalypse World to the Winchesters and provides Dean with a machine gun loaded with angel-killing bullets to fight Lucifer with.
In season thirteen's "Good Intentions", Mary Winchester and the Nephilim Jack encounter the alternate reality Bobby after escaping from the custody of the archangel Michael.
Actor Jim Beaver described Bobby as a "rough but warmhearted" working-class man with the outlook that "sometimes there are things that need to be done and they're not fun to do, but they gotta be done anyway.
[21][29] However, the actor did "[take it] very seriously," and commented, "I can get out of the chair at the end of the day and go home and I recognize that, so many people can't and I have to be considerate to them and respect that.
[31] Likewise, Karla Peterson of The San Diego Union-Tribune suggested, "May his trucker cap get its own star on the Hollywood Walk of Fame.
"[35] IGN's Diana Steenbergen also praised Beaver, calling Bobby "a valuable member of the team" that "broadens [the Winchesters'] tight-knit unit, reminding them that there is more to family than just blood ties".
Not solely a surrogate father figure and keeper of random supernatural knowledge, this season Bobby has run the gamut of sacrifice, loss, anger, and determination to keep fighting.
Don Williams of BuddyTV, however, defended him—he believes Bobby to be the show's "most important recurring guest star"—and noted that "people will complain about anything".