Not much is known about No-bark Noonan's past. However, when asked about his nickname, he reveals that he suffered from multiple radscorpion stings that have pierced his skull. The event undoubtedly made him into the man he is. He also claims to be a scientist, which he may have been in the past before being stung by radscorpions.
He wanders the streets of Novac, looking into windows and spouting conspiracy theories and other ramblings that sometimes have nuggets of truth hidden in them. It's not exactly certain how he earned his nickname, although Alice McBride, a Novac resident, believes that his name comes from the phrase "not all of his dogs are barking." No-bark says otherwise; he claims that "they know I ain't just barking here. What I say's got bite, 'cause it's the truth."
Come Fly With Me: While No-bark has no clue what is going on at the REPCONN Facility, he states that he believes the plant is inhabited by "commie ghosts that don't know they're dead." He speculates that their plan is to hijack the nearby rockets, so they can travel to the moon, paint it pink and "draw a Lenin face on it."
Upon meeting No-bark, he threatens to stick the Courier with his "stickin' knife." No-bark is also extremely paranoid about communists and has many pro-American posters covering the walls of his shack. Some of the posters will be familiar to those who have played Fallout 3, as they are posters that are seen in various locations in the Capital Wasteland and in that game's loading screen slides.
After the Courier completes Come Fly With Me, Radio New Vegas takes an interview with him, where he correctly states that the rockets belong to "religious ghouls looking for a land to call their own." He further states "Don't you laugh at me! I know a spell that will make you show your true form! Cave rat taught it to me." He does this interview while speaking to a teddy bear near a microphone.
No-bark introduces himself to the Courier by threatening to stab them with a knife he calls Ol' Sticky, even though he isn't carrying one. While something like this might normally be disregarded as rambling, options in the Courier's dialogue imply that he really does have a knife, or at least that he should.
With a Strength of 6 or more, the Courier can threaten No-bark to tell them everything; this has no effect on what he says, other than a small amount of experience. There will be no Karma or reputation loss, however.
No-bark is the one character in New Vegas that seems to be able to play Caravan no matter how much money he has left. He is much wealthier than he seems, being able to bet 1,000 caps in a caravan game.
"I don't trust a man that doesn't have something strange going on about him, cause that means he's hiding it from you. If a man's wearing his pants on his head or if he says his words backwards from time to time, you know it's all laid out there for you. But if he's friendly to strangers and keeps his home spick-and-span, more often than not he's done something even his own ma couldn't forgive."
No-bark Noonan references Vladimir Lenin, the founder of the Communist Party of the Soviet Union.
The following is based on unverified behind the scenes information and has not been confirmed by canon sources.
"Commies" painting the moon is another reference to Robert A. Heinlein in "The Man Who Sold the Moon", D.D. Harriman convinces a US businessman that the Russians intended to get there first, to paint the Hammer and Sickle on the moon.
End of information based on unverified behind the scenes information.