Treated as a freakish, second-class citizen by many people in Megaton (particularly Colin Moriarty), Gob is skittish and nervous, always looking over his shoulder. He does his best to maintain a sense of humor and to be friendly with customers, but this is mostly out of his desire not to be beaten. Confessor Cromwell and Mother Maya treat Gob with respect and an air of reverence because of their spiritual beliefs.
Gob used to live in Underworld with his adoptive "mother", Carol, in Carol's Place. He set out into the Wasteland to find fortune and was caught by a group of slavers. Colin Moriarty then purchased him as his slave. He works for Colin Moriarty to repay the debt presumably incurred when Moriarty purchased Gob from the slavers. Gob has been working to repay his debt for 15 years, since Moriarty also charges Gob for rent and food.
Gob spends most of his time serving drinks and talking with the patrons in Moriarty's saloon. At night, he'll eventually go to sleep in the rentable room, sometimes resting for a few hours and then starting up the saloon in the early morning hours. During his working hours, he'll be cleaning glasses, communicating with people ("What, you never seen a ghoul before?"), tidying up the place with a dirty broom and checking the shelves behind the counter to see what's currently in stock. The first time the player enters the saloon, Gob will be hitting the radio, trying to fix it. Nova tries to explain to him it doesn't work, and Jericho (if he is present) cursing him to stop banging on it. After the player completes the Galaxy News Radio quest, the radio will function properly, though Gob will never comment on its improvement.
If you kill Moriarty, Gob will eventually take over the saloon and place his name over Moriarty's on the front sign. However, he gets no new speech options and in no other way acknowledges Moriarty's absence. Nova will begin running the hotel and quit prostituting once Gob is in charge.
When first meeting Gob, treating him kindly will provide a 10% discount at the saloon (and only from Gob, Moriarty will charge full price), gain the player some good Karma, and reveal some more of his personal past. The discount is especially useful as Gob remains a cheap source of stimpaks for the entire game. You lose the chance to obtain this discount if you first talk to Gob after Moriarty is killed.
If on first meeting the player says to Gob, "Stuff it, ghoul.", or, "Gah! What the fuck are you?" and is not kind for the rest of the conversation, he will refer to you as a "dick" every time you ask for a drink.
In non-player character to non-player character conversation, Nova can be heard telling Gob that she has "arranged time" for the two of them, though at another point she tells the player that there are "some places even I won't go".
In non-player character to non-player character conversation, Gob will tell Nova that he pulled aside a specific bottle of wine that makes her "uninhibited", to which she calls him "Gobbie", before he states he'd do anything for her.
If you kill anyone in Megaton, Gob will then say: "Dont shoot! Dont shoot! Just tell me what you want!" everytime you interact with him.
If Mr. Burke kills Lucas Simms in the Saloon, Gob will complain about it "taking forever to clean the blood stains from the floor".
If Lone Wanderer is not friendly with Gob (calling him a zombie first time he meets Gob), he won't tell you about Moriarty's terminal.
Gob will most likely be the first ghoul character you meet if you go straight to Megaton after leaving Vault 101.
If the player finishes the quest "Following in His Footsteps" without entering the saloon (i.e. going directly to GNR), after fixing the radio signal and entering Moriarty's Saloon, Gob will be found banging on the radio and complaining, despite the station coming in clearly.
There is a slight inconsistency regarding the origin of Gob's name. While yelling at Gob in random non-player character to non-player character conversation, Moriarty says, "Shut yer gob, Gob! Ain't that why I named you that to begin with, 'cause you talk too goddamn much?"; yet Carol knows exactly who the player means by "Gob," though she never met Moriarty or knew that he called him "Gob."