When General Fernando Matthei steps out to vote in Chile's presidential election on Sunday, three names will echo back at him through 40 years of history. First, there is his daughter Evelyn, just turned 60, standard bearer of the beleaguered right. Then there is Michelle Bachelet, daughter of his erstwhile childhood friend Alberto, another air force general who found himself on the receiving end of the coup that tore Chile apart 40 years ago. Finally, there is Marco Enríquez-Ominami, son of the revolutionary leader executed by the post-coup regime that Matthei supported through the prime of his career.

Three candidates, three fathers, one election. And an awful lot of history.

Evelyn Matthei, representing the rightwing Alliance that governs the country, is in dire need of her father's vote. She not only trails former president Bachelet by at least 20 points, but also could even be knocked into third place, a result that would be ignominious for Chilean conservatives that managed, only four years ago, to elect Sebastián Piñera as head of state.

But to General Matthei, the Bachelet name means far more than a candidate on a ballot slip. Alberto was his close friend, a man whom his daughter called Tio [Uncle] Beto, who died in March 1974 of a heart attack brought on by the torture he was subjected to during the six months that followedfollowing the September coup that ousted democratically elected president Salvador Allende.

Fernando Matthei was a military attache at the London embassy when the coup led by Augusto Pinochet destroyed Chilean democracy. He could do nothing to help the friend with whom he used to exchange classical records and talk into the night about sports, politics and literature. But his failure to act could no longer be justified, however, when he returned to Santiago at the end of 1973 and was named director of the aviation's War Academy – the very building in which Alberto Bachelet was to die two months later. Though several judicial reviews and trials found that then Colonel Matthei had no penal culpability in the death of General Alberto Bachelet – the cellars where his comrade-in-arms were being tormented were off limits to anyone not working as an interrogator – the guilt still haunts him. In his 2009 book, he admitted: "Prudence outweighed courage."

Not even the most delirious novelist could have imagined a more unusual history of differing destinies. One dies because he had the courage, though perhaps not the prudence, of accepting to head the distribution and food centre of Allende's government, a post that had ministerial status. The other lives a life of excessive prudence and no courage and is ultimately named to the ruling junta. General Matthei also served as health minister in Pinochet's cabinet – a portfolio that Michelle Bachelet held a generation later. As for Evelyn Matthei, she was a senator and then labour minister in Piñera's government. A study in contrasts: the socialist who became Chile's president and the conservative who aspires to that presidency.

But there's another twist. In the polling booth, General Matthei will not fail to recognise the name of another candidate whose father will not be able to vote because he was killed by the dictatorship. Marco Enríquez-Ominami is the son of Miguel Enríquez, the legendary leader of the Movimiento de Izquierda Revolucionaria (Movement of the Revolutionary Left) who was riddled with bullets on a Santiago street in October 1974. Marco was 18 months old at the time. Forty years later, he is catching Evelyn Matthei in the polls. If he eclipses her, he will face Bachelet in a runoff, allowing the people of Chile to choose between two progressive candidates and their vision of the future. It is an improbable scenario but not impossible if we let imagination run wild.

Of all the protagonists of this story, Miguel is the one I knew best. My wife Angélica and I were his friends to the point that, though we did not agree with his theory of armed struggle as the path to freedom, we risked our lives in order to give him and other MIR militants refuge in our small house in Santiago in 1970 when they went underground during the administration of Christian Democrat Eduardo Frei Montalva proclaiming the need for a Cuban-style assault on power.

What would Miguel say if he could see his son upholding the need to transform and modernise Chile using peaceful means, if he could watch his son refusing the violence he himself feverishly believed in? So many other Latin American revolutionaries who survived the dictatorships of the past came to understand that democracy, rather than the straitjacket of the poor seeking liberation, is the essential precondition for any deep change, any permanent justice. Perhaps then, Miguel would have matured in a similar way, Miguel who was so imprudent in ideas and actions but at the same time showed such exemplary courage in his life, so animated by a thirst for a better world that still moves me when I think of him. I would have liked to have discussed these and other matters, as we did such a long time ago when he slept at our house in Santiago.It is a conversation we will never have.

Presidential hopeful Marco Enríquez-Ominami was 18 months old when his father was killed. Photograph: Felipe Trueba/EPA

The regime that Fernando Matthei served with such blind allegiance executed Miguel Enríquez in cold blood, killed him as it killed and disappeared thousands of other compatriots.

If the son of one of the victims would beat the daughter of one of the accomplices, would that not suggest that Chile has definitely turned its back on the legacy of Augusto Pinochet and his dictatorship?

But there is in this implausible story of ghosts and fathers, children and guilt, yet one more turn of the historical screw. It was the same craven General Matthei who ultimately helped Chile on to the road of the free elections it now takes for granted. Matthei's redeeming moment came the night of the 1988 plebiscite, which would decide whether Pinochet retained power indefinitely. When Pinochet tried to deny his defeat at the ballot box and launch another coup, it was General Matthei who blocked that manoeuvre, publicly recognising the victory of the No option, and thus opening the way for Chile to return to democracy.

I would like to believe that Fernando Matthei, that night of the plebiscite, was paying a debt he owed to his old friend Alberto, confronting Pinochet with the valour he had not shown 14 years earlier when he had not even dared to visit, let alone console, the comrade who was being tortured a fewyards away from his office at the War Academy.

It is a debt, however, that has not yet been entirely settled. General Matthei, now 88 years old, still has another gesture of redemption with which he would be able to silently signal his real repentance, dispel, perhaps for ever, the phantoms that will not leave him alone. It would be a simple gesture, though not without risk. All it would take is for the general, when he enters the polling station on Sunday and looks at the list of candidates for president, to decide clearly and categorically to mark the name of Michelle Bachelet. Perhaps he knows it would mean the world to her that her Tío Fernando cast that vote, cast it because her father Alberto unfortunately cannot do so.

Ariel Dorfman's latest book is Feeding on Dreams: Confessions of an Unrepentant Exile. He lives with his wife, Angélica, in Durham, North Carolina and, when time permits, in their native Chile