When the news broke on 7 October that the Peruvian novelist Mario Vargas Llosa had won this year's Nobel Prize for literature, a rumour began to skitter round the internet that the 1982 laureate, Gabriel García Márquez, had written one of the shortest recorded observations of his long literary career. "Cuentas iguales", his alleged message on Twitter read: "We're even."

It took the weight of Jaime Abello, director of García Márquez's Foundation for New Ibero-American Journalism, to kill the story. Gabo, he assured the disappointed press, did not tweet, had never tweeted and did not ever plan to tweet. And if Gabo should have some comment to offer about the new laureate, he would choose his moment and his medium. So far, he has maintained an eloquent silence. It takes more than a Nobel Prize, it seems, to call time on one of the world's best-known literary feuds.

At 74, Mario Vargas Llosa is still a prolific and justly celebrated writer, the author of more than 30 novels, plays and works of non-fiction. He was a member of a wave of Latin American writers, including García Márquez and the late Argentinian novelist Julio Cortázar, who had a transformative impact on the literature of Latin America in the 1960s and 1970s. Though individually very different, collectively they gave literary voice to a subcontinent in the throes of political struggle.

Vargas Llosa's career began with a bang. His first novel was The Time of the Hero, published in 1963. It was drawn from his miserable passage through a military academy in Lima to which he had been despatched by his authoritarian father, and won immediate attention and a literary prize. His second, The Green House, published three years later and set in a brothel, was received with even more enthusiasm and a clutch of awards, confirming his place among a group of writers with a growing international influence and reputation.

Like so many of his Latin American contemporaries, Vargas Llosa grew up in a country blighted by military rule. He interwove the personal and political narratives of the day in such novels as Conversation in the Cathedral, set in Peru under Manuel Odría's dictatorship. His was a cohort inspired by Cuba in 1959, when Fidel Castro's chic young revolutionaries drove the US-backed dictator Fulgencio Batista into exile. It seemed to promise a new future for the region, and the writers, Vargas Llosa among them, supported Cuba energetically.

By the 1970s, however, guerrilla movements across the subcontinent had sought to emulate the Cuban success and were being savagely repressed by US-trained Latin American security forces. Torture and disappearance became routine weapons to use against a generation that demanded change, sometimes, but not always, with the gun. For many the blood-soaked decade confirmed that US domination was the source of Latin America's evils and Marxism the remedy. Vargas Llosa moved in the other direction.

Disillusioned by the growing authoritarianism of Castro's revolution and outraged by its treatment of such writers as Heberto Padilla, he broke with the Cuban regime. His journey from leftist fellow-traveller to admirer of Margaret Thatcher had begun. A left-to-right move over a lifetime of engagement is hardly unusual, but in Latin America's polarised politics it marked Vargas Llosa out from his contemporaries. It also formed the backdrop to another defining feature of his career, a penchant for very public quarrels, starting with his literary senior Gabriel García Márquez.

In 1971, Vargas Llosa had published his doctoral thesis as the book García Márquez: Story of a Deicide, a warm tribute to the importance of hisfellow author - but in 1976, he gave García Márquez a black eye at a cinema in Mexico City. The two have not spoken since.

There was a personal backstory to the quarrel: though neither man will explain, Vargas Llosa was heard to say, "How dare you come and greet me after what you did to Patricia in Barcelona?" as he swung his fist. Patricia is Vargas Llosa's second wife (and first cousin); friends believe García Márquez had advised her to leave him during one of Vargas Llosa's passages of infidelity. They also suggest that he thought García Márquez had taken too close an interest in Patricia. Naturally, these explanations are not mutually exclusive.

Perhaps it also had an element of literary parricide. Any writer in Latin America at that time risked being defined against One Hundred Years of Solitude, the novel that catapulted García Márquez to global fame and is still a bestseller, and Vargas Llosa's punch may have liberated him from his ex-friend's shadow. He went on to attack García Márquez for remaining a privileged camp follower of the Cuban regime.

Vargas Llosa's public disagreements have been sharpened by politics. Each falling out marked a stage of his journey to the right, and by the late 1980s the writer's political engagement had moved on to the hustings. Despite his combative history, he does not, in person, seem like a bruiser. Tall, good-looking and with the social graces of the Latin American elite, he is driven by passions, which he pursues, in the moment, with absolute certainty. Even when they have turned out to be mistakes, there has usually been a book in it.

His personal passions included his elopement at the age of 19 with Julia Urquidi, an aunt by marriage. She was a divorcee, and 13 years his senior. The marriage generated both Vargas Llosa's popular, humorous novel Aunt Julia and the Scriptwriter (1977) and, some years later,
a riposte from Aunt Julia entitled What Little Vargas Didn't Say.

Vargas Llosa's quarrel in the 1980s with the president of Peru, Alan García, was entirely political. García, a charismatic but unstable character, was the last of Peru's avowedly left-wing leaders - today a reformer - and was first elected in a landslide in 1985. Peru was in crisis. A Maoist insurgency, Sendero Luminoso, led by Abimael Guzmán, was threatening apocalypse from the Andes and the economy was collapsing. García's presidency, marked by authoritarianism, human rights abuses and runaway inflation, nearly pushed it over the edge.

For Vargas Llosa, disenchanted by the dogmas of the left and by now an admirer of Thatcher, the last straw came in 1987. He was relaxing at his beach house on the outskirts of Lima when he heard the news on the radio: García planned to nationalise the banks, in an attempt to confiscate what remained of Peru's wealth for his failing project. Within a few days, Vargas Llosa and a group of friends had decided that he would contest the elections in 1990.

With his son Álvaro in charge of press relations, he launched a campaign that, despite victory in the first round, ended in rancour and defeat. His neoliberal project and frank account of his proposed economic remedies played badly with Peru's poor, who saw it as an elite venture. Vargas Llosa lost in the second round to one of the most unlikely, and catastrophic, politicians Peru has ever produced, Alberto Fujimori.

It would be foolish to argue that Vargas Llosa was as good a politician as he is a novelist, but he could hardly have proved worse than either García or Fujimori. Two years after his victory, Fujimori dissolved congress and suspended the constitution while, under cover of a state of emergency, the lawyer Vladimiro Montesinos, the sinister power behind the throne, enacted a reign of terror and corruption. After ten years in office, Fujimori fled to Japan when he became implicated in a corruption scandal; he was eventually extradited and convicted on charges ranging from kidnapping to embezzlement.

It is hard to lament Vargas Llosa's failure. From his self-imposed exile in Europe, he published A Fish in the Water, a memoir of his run for the presidency, in 1993. Several more works of non-fiction and six novels have followed, including the landmark Feast of the Goat, about the attempted assassination of Rafael Trujillo, dictator of the Dominican Republic from 1930-61. His journeys have ended where they began, not in an embrace of dogma, but exploring the individual's struggle for self-realisation against oppression from both left and right.

Isabel Hilton is editor of chinadialogue.net