NELSON MANDELA & F.W. DE KLERK

Two days before receiving his Nobel Peace Prize, African National Congress (A.N.C.) President Nelson Mandela entertains visitors and well-wishers at the Grand Hotel in Oslo, Norway. Tall, exquisitely tailored, he dispenses soft handshakes and his world-famous smile. The 27 years he spent in South African prisons seem somehow to have left him younger than his 75 years; he looks well + rested and benign. The mention of a newborn baby boy makes him beam. Because of his confinement, he did not get to see his own two youngest daughters grow up, and since his release he has kindled a love affair with his grandchildren. Gradually, as Mandela begins to talk of how his fellow Peace Prize winner, South African President F.W. de Klerk, has ''disappointed'' him during their long, tortuous negotiations toward a new, free, just South Africa, his sunny demeanor fades. Once started on this subject, he has trouble stopping. His voice rises; the smile becomes a scowl. Blacks have been killing other blacks in gruesome ways and growing numbers back in his country, and Mandela says he knows who is partly to blame: ''There is no doubt that the National Party is involved in violence; we have got very solid evidence.'' Two days after the Nobel ceremony, De Klerk, 57, sits in an ornate suite in another Grand Hotel, this one in Rome, Italy, where he awaits an audience the next day with Pope John Paul II. For someone who has just been heralded and laureled as a peacemaker, De Klerk falls into moods that border on the bellicose. He is irked at his co-recipient and dissatisfied with what he takes to be the world's misunderstanding of himself. Smaller, more delicately featured than he appears in photographs, the President nurses a Scotch and cannot resist complaining. He feels Mandela has upstaged him in Norway and maligned him in general. He, the son and grandson of National Party leaders who helped erect the artifice of apartheid, has traveled further from his heritage than anyone could have predicted. He has dismantled the past and prepared his nation for democracy. And what does he hear from Mandela, the A.N.C. and others? That he is a foot dragger, unconcerned with the injustices and violence suffered by blacks in his land, even, perhaps, secretly instigating such turmoil; that he is not an architect of progress but at times its impediment. ''If I start defending myself on that,'' De Klerk says, hunching forward in his chair and clenching his teeth, ''I would also have to go on the attack.'' The mutual bitterness and resentments between De Klerk and Mandela are palpable. How could these two have agreed on anything -- lunch, for instance, much less the remaking of a nation? In one sense, the answer is simple. Mandela and De Klerk perfectly meet the first precondition of peacemakers: they do not like each other very much. Harmony is only intermittently an issue between friends; the intractable messes of human coexistence are left for enemies to hammer out. In attempting to do this most difficult thing, Mandela and De Klerk have been forced into a fascinating pas de deux, coordinating their steps while not so secretly resenting the necessity of their partnership. ''Mandela and De Klerk,'' says A.N.C. spokesman Carl Niehaus, ''were delivered to each other by history.'' Neither one, in the season of their triumphs, seems grateful for the gift of the other. But those triumphs are immense. These unlikely allies created the conditions for an event the world could