On Monday, the rebel former seminarian known as Ivan Marquez and government representative Humberto de la Calle, a sage veteran of Colombian politics, will sit down in Havana to negotiate in earnest.
The two have little in common other than eyeglasses, a slight paunch and a previous failed attempt to talk peace.
"The men sitting down at this table are enemies. They are trying to become friends," said Horacio Serpa, who was Colombia's interior minister during the mid-1990s when De la Calle was vice president.
Marquez and De la Calle offered very different views of reality in Oslo that made many wonder whether this fourth attempt at peace since the 1980s can succeed.
The No. 2 commander in the Revolutionary Armed Forces of Colombia, or FARC, insisted on radical change: Take control of the nation's oil and mineral wealth from multinationals and give it to the people.
De la Calle reiterated on Sunday, as the government delegation departed for Havana, what he said in Oslo: Colombia's economic model is not subject to negotiation.
"But we also aren't asking the FARC to abandon its ideas," he said in brief comments at the airport.
The government he represents, led by President Juan Manuel Santos, seeks greater foreign
Neither side has illusions about the difficulties. But there is an agenda, reached in seven months of secret talks, also in Havana. First up is land reform, the heart of the conflict.
The FARC is insisting on the public's participation in the talks, and De la Calle said both sides have been "working on tools to facilitate citizen participation" that include "a website and other mechanisms that will become known in coming days."
The 66-year-old De la Calle is best known for quitting as vice president in 1996 after his boss, President Ernesto Samper, was accused of winning the presidency with $6 million in contributions from the Cali cocaine cartel. De la Calle is from Manazares, a coffee-growing town in Caldas state.
Marquez, 57, hails from Florencia, the capital of the southern state of Caqueta that has long been a rebel bastion.
Born Luciano Marin Arango, Marquez took his nom de guerre from a labor leader assassinated in the 1980s. He studied to be a priest in Garzon, in the central state of Huila, but dropped out after two years. He later studied philosophy in Bogota but didn't finish that either, and after two years as a biology teacher in Florencia joined the Communist Youth in 1977.
De la Calle was a law school dean at the time. In 1982, he was named head of Colombia's national elections commission and held the job when Marquez ran in 1986 as an alternate for Congress on the ticket of the Patriotic Union, the political wing that the FARC created after reaching a truce with the government.
It was a dangerous time to be a Patriotic Union activist. At least 3,000 members were systematically slaughtered by right-wing death squads, and Marquez was among many who joined the armed rebels. A movement that barely surpassed 1,000 fighters at the beginning of the 1980s began growing quickly.
Carlos Romero, the Patriotic Union's president in 1989, remembers Marquez as quiet and industrious, organizing meetings and documents in a subsidiary role to Alfonso Cano, who would later become the FARC's top commander and was tracked down and killed last year by the military.
De la Calle became a Supreme Court justice, then entered politics. After losing the Liberal Party presidential nomination to Samper, he became Samper's running mate, but quit in the heat of a drug-related finance scandal.
It was a time of disintegrating government control of the countryside, of historic FARC victories over a dispirited military, when private far-right militias known as paramilitaries massacred suspected rebel sympathizers.
De la Calle, who is married with three children, took refuge from his agitated public life by being "in love with literature, with poetry ... a lover of good music, both classical and Colombian," said Carlos Holmes, a friend and former education minister.
Little is known of Marquez's private life except that he has eight siblings and three children from a marriage that pre-dated his life as a fugitive, according to government intelligence officials who spoke on condition of anonymity because they were not authorized to discuss the matter. They said Marquez operated as a rebel commander in the Caribbean banana-growing region of Uraba, where the FARC took a beating from paramilitaries and murders of union organizers by right-wing death squads were rampant.
In 1991, Marquez was named to the FARC delegation for peace talks in the Venezuelan capital of Caracas after being promoted to the rebels' seven-man ruling Secretariat.
It was in Caracas that he and De la Calle met for the first time.
The two "carefully measured their words in public and in private. They committed no imprudences," said Hector Riveros, a government negotiator at the time.
He remembers Marquez as being opposed to the negotiations.
Ironically, so apparently was De la Calle. Or so he was ordered.
De la Calle only showed up for the talks' inauguration, and was ordered home by then-President Cesar Gaviria because the latter wasn't interested in serious talks, said Alvaro Leyva, a Colombian politician from the Conservative Party trusted by the rebels who would later help arrange 1999-2002 peace talks.
Gaviria thought the FARC could be beaten on the battlefield, Leyva said.
At any rate, conditions were not good for peace. A coup attempt led by Hugo Chavez convulsed Venezuela in 1992, and Gaviria's government was battling cocaine kingpin Pablo Escobar, who was killing civilians indiscriminately and would be tracked down and killed in December 1993 with U.S. help. The talks moved to Tlaxcala, Mexico, where they died.
Marquez and De la Calle didn't meet again until Oslo.
Because he is viewed as having no presidential ambitions, De la Calle was a good choice to lead Santos' negotiating team to the current talks, even though he didn't participate in the secret talks leading up to them, Riveros said.
The role of chief FARC negotiator fell to Marquez pretty much by default.
The rebels have lost their four most senior commanders since 2008 as a U.S.-supported military buildup depleted their ranks, triggering record desertions. Three members of the ruling Secretariat were killed in military attacks, including Alfonso Cano, with whom it had kick-started the current peace process. A fourth, founding leader Manuel Marulanda, died in a jungle camp, apparently from a heart attack.
During much of that time, Marquez is believed to have been living in Venezuela.
Associated Press writers Cesar Garcia and Libardo Cardona in Bogota and Frank Bajak in Lima, Peru, contributed to this report.