Cornelius, the protagonist
Cornelius is a person in mourning who has to face the truth of the Rwandan Genocide from the perspective of a person whose family was slaughtered. Cornelius wants to understand the narrative of the genocide, so he tries to write a fictional account of what happened. He is half Hutu and half Tutsi, so eventually, he has to reconcile himself to the fact that his own family betrayed itself.
Diop, the author
The author writes himself into the story. Whereas Cornelius is interested in writing fiction, this character wants to write non-fiction. He learns about the issues in Rwanda as a reporter would, and the character's inclusion in the story helps the reader to learn the technical details of the genocide, its true effectiveness, the horror of how it happened, and then also why no one intervened while ethnic genocide was being committed.
Cornelius's father
During a conversation with a local family man, the reader learns the truth about Cornelius's father. During Cornelius's time abroad, he believed that his father was eventually killed by the genocide. He talks about his father like he was one of the tragic deaths, but eventually that conversation reveals the truth that actually, the father was one of the most active participants in the genocide, betraying his wife and kids to incite a murderous riot in Cornelius's hometown that ended up killing almost 60,000 people.