Robert Chalmers doesn't like... Arianna Huffington

There is, Arianna Huffington wrote, in her book The Fourth Instinct, "a great deal that we share with the faithful St Bernard." It's hard to know what qualities she was alluding to: perseverance, perhaps; selfless courage, and, as the old joke goes, an irresistible compulsion to turn around three times before lying down.

Aspects of Huffington's own character invite comparisons with the canine world, though most – her ferocious instinct for self-advancement, appetite for celebrity and glacial hostility when confronted – are rarely associated with the amiable custodian of the brandy barrel. In terms of best of breed, Huffington has more in common with a status dog.

This woman has walked across hot coals, had intimate relations with John Selwyn Gummer ("I am drawn to thinking men") and reportedly been baptised in the Jordan by a former English teacher who woke from a botched kidney-stone operation believing he was bigger than Jesus. By contrast with these challenging experiences, The Fourth Instinct is a disappointingly orthodox piece of prose.

But whose pen could possibly do Arianna Huffington justice? Rendering her mutations credible in fiction would be a task that might have defeated Kafka. For years a keen defender of the right of the UK Conservative Party, and ally of staunch Republican Newt Gingrich, she has morphed into an icon of independent liberalism. In February she sold her website, The Huffington Post, to AOL for $315m. (None of which has been shared with the Post's 9,000 bloggers.)

I met her in 1995 in Washington DC when, having already perfected a demeanour reminiscent of The Stepford Wives, she argued for the dismantling of public services, including the NHS. She was thenArianna Stassinopoulos-Huffington, married to Republican Michael Huffington, who spent $28.3m of his own fortune unsuccessfully running for the Senate.

Is there an uglier sight in politics than a figure whose ruthlessness appears to dictate their principles? By 2003 Arianna (divorced from Huffington in 1997), sensing that the action was now on the left, would be running as an Independent for Governor of California, supported by libertarians including the comedian Doug Stanhope. By the following year, she was endorsing the Democrats.

Arianna Stassinopoulos, daughter of a Greek journalist, attended Girton College, Cambridge. A fellow student recalls the first foreign female president of the union as "pretty right-wing, even then. Arianna was driven by ambition rather than politics".

You don't get called "The Edmund Hillary of Social Climbing" for nothing. By the mid-Seventies, she was appearing on shows like Any Questions, despite an accent once described as "Zsa Zsa Gabor on Quaaludes."

Perhaps her most remarkable achievement has been to erase in the collective memory her once close association with Roger Hinkins, the LA schoolteacher who was unaware of his cosmic significance until that surgical intervention in 1963. When he awoke from a coma nine days later, he was John-Roger ("John the Beloved"), embodiment of the "mythical consciousness".

Former acolytes have testified how the corpulent mystic cultivated an inner circle of young male members. "Someone had to stay up all night and protect his body from demons while he did mystic travel," one ex-follower told me. "To the uninitiated, it looked like an old man snoring."

Stassinopoulos met him at a party in the early Seventies, and her past support of John-Roger's organisation MSIA is a matter of record, though by 1995 he was "no more than a friend. Everything I did with John Roger," she told me, "was a positive experience." In the late Seventies, when she was promoting the "Insight" self-awareness group, founded by John-Roger, she famously persuaded her then lover Bernard Levin to dress in a pink tutu.

But nothing touches her: not even repeated allegations of plagiarism (she settled out of court with regard to her book on Maria Callas; similar accusations were levelled at her work on Picasso – "a dog of a book", according to art critic Robert Hughes). The most contentious aspect of Huffington's history raised during one BBC radio interview last week was an allegedly excessive affection for homeopathy.

It may be hard to empathise with Huffington, I once suggested to the commentator Christopher Hitchens, but it's difficult not to envy her unshakeable self-belief. "I think of her rather like Nixon." Hitchens replied. "People who won't quit because they have no sense of shame or embarrassment ... generally get at least some of what they want. Arianna," he added, "Just keeps on coming."

And that last statement, in the malleable history of Arianna Huffington, is that rarest of things: a fixed and uncontentious truth.