One of the defining characteristics of fictional responses to the Rwanda genocide is a concern with documenting and remembering the truth about what happened in 1994. The importance of accurately describing the horrors of the genocide is summarized in the quotation from German playwright Peter Weiss that Rurangwa chooses as the epigraph for his novel, Au sortir de l'enfer:

In order to convincingly tell a story that has been repeatedly described as unspeakable, untellable, incomprehensible, unknowable, authors rely on witness accounts from Rwandans who were present in 1994; real–life stories that have been passed on to them or those they have experienced first–hand. Bearing witness about the genocide requires remarkable courage, strength and determination. It is therefore not always easy to find primary witnesses who are willing to give testimony. Many witnesses are already dead, in exile or in prison. This explains the search for witnesses that runs through many of the genocide novels and is particularly strongly felt in Ndwaniye's La Promesse faite à ma soeur. Having returned to his Belgian home after searching for the truth about what happened in Rwanda, the narrator writes:

Most of the people who witnessed the horror are now dead.