This has been a contentious subject more or less since the news of private conversations between them became public and remains contentious right into the present moment of de Klerk's death.

The complicated noise here from a historian's perspective is that the nature of these conversations has been politically important to both men from the outset, and has been legally or procedurally important to de Klerk once he ceded his political authority in the transition to majority rule.

De Klerk's own account, detailed in his rather unrevealing autobiography and various public statements over the years, is that he was a loyal National Party stalwart with deep roots in Afrikaner nationalism who pragmatically believed that the course of action taken by P.W. Botha during the 1980s was unsustainable and that the white minority would have to bend or be broken. Hence, when Botha was incapacitated by a stroke, de Klerk represents himself as stepping forward and seizing the reins to make some changes, most notably to open negotiations with Mandela. Still, it's hard not to note that in de Klerk's own accounts of the early meetings with Mandela, he's incredibly circumspect--he could "do business" with him, but there's no real warmth or personal depth of feeling in his recollections.

On the flip side, in his autobiography and in other biographical accounts, Mandela represents himself as deeply skeptical about approaches from the National Party leadership, which began under Botha's rule, but that he felt de Klerk "actually listened" when they had their first conversation, whereas the approaches from Botha felt like pro forma attempts to compromise him. Mandela is considerably more effusive and detailed in his appraisal of the few white prison guards that he came to like, for one point of comparison.

For both men, it appears that their conversations were business-like and goal-oriented. That in and of itself felt like progress in the moment, but considering the numerous odd-bedfellows friendships and alliances in the years before and after the end of apartheid, de Klerk and Mandela don't seem to have been more than guardedly pragmatic in most of their in-person conversations.

Both men were extremely anxious to not overpromise or to make agreements that their own supporters would undo, and Mandela was especially intent on having de Klerk acknowledge that Mandela was speaking *for* the ANC and must be allowed to freely consult with its leadership before any agreement and that the ANC was speaking *for* the majority of South Africans. The former proposition is something that de Klerk could allow (considering that it was obvious anyway); the latter was at the heart of future possible agreements.

In the end, both men in their post-facto memoirs and statements seem to agree that these early conversations were surprisingly frank, respectful and productive--which led to de Klerk's still-shocking and unexpected decision to release Mandela, to release the ANC's leadership. to decriminalize the ANC, and to open negotiations on a future constitution.

Where things get much more dicey in terms of competing representations of future conversations involve the move towards those negotiations. De Klerk insisted later that he made a move towards negotiations out of strength--a feeling that with the end of the Cold War, white South Africans needed to no longer fear Communist takeover--whereas Mandela and his associates insisted (I think accurately) that de Klerk was acknowledging the extent to which mass protests had rendered the country effectively ungovernable by the white regime and put the future security of the economy and the society in serious doubt.

Both men frequently accused each other of bad faith in quite personalized ways during the neogtiations over the constitution and Mandela in particular claimed that de Klerk often misrepresented either the state of his knowledge of covert activities by the apartheid state's remaining security forces and their allies or his actions in preparation for a future majority rule state. (Among them, the massive destruction of apartheid-era government records, which it is fairly certain now that de Klerk not only knew of, but personally approved.) In this era leading up to the election of 1993, finding moments of retrospective (or contemporaneous) agreement about who said what to whom and in what tone or spirit is much more difficult. What is certain that that by the time de Klerk left the unity government, neither man felt any warmth or appreciation for the other, though I think Mandela's bitterness towards de Klerk was more pronounced, and I don't think that was simply a case of Mandela playing towards his own party base.

The lingering feeling that de Klerk in particular shirked his agreed commitment to honest testimony before the TRC process added to those bitter feelings.

For primary readings, de Klerk's autobiography The Last Trek and Mandela's Long Walk to Freedom (both of them likely having significant amounts of ghostwriting in the mix) are somewhat useful in seeing how both men worked to represent what they said in their meetings with one another.

By the time of the Nobel Peace Prize awarding, Mandela's anger with de Klerk was unusually visible and fairly personal. De Klerk himself talked about it in this PBS interview (and talks about it some, in fairly limited ways, in The Last Trek): https://www.pbs.org/wgbh/pages/frontline/shows/mandela/interviews/deklerk.html.