He is portrayed as a cynical, mentally unbalanced, Gonzo journalist[citation needed] whose daily life is a near-perpetual state of intoxication on whatever drugs happen to be available – ranging from cannabis to amyl nitrite to adrenochrome – in an attempt to keep the spirit of the 1960s, a time which he speaks of romantically in Fear and Loathing in Las Vegas, alive within himself even as the rest of the country forgets it and what it represented.

He usually obtains and consumes these substances in the company of his attorney, Dr. Gonzo, a "half-crazed 300 pound Samoan", whose drug-induced frenzies give even Duke pause.

[2] Duke is first mentioned by Thompson in his 1966 book Hell's Angels, where he is described as an outlaw who does not break the law in an offensive way to society, but a way that in fact makes him more acceptable.

[4][5] His name, according to Thompson in interviews, was inspired by Raúl Castro and John Wayne's nickname "The Duke"; however, David S. Wills, in High White Notes: The Rise and Fall of Gonzo Journalism, argues that he borrowed the name from a newspaper article during his research for Hell's Angels.

In the same section, Thompson calls journalistic objectivity "a pompous contradiction in terms", and warns the reader not to look for it under his byline.