The Once and Future King Book 4, Chapter 4

Lancelot and Guenever talk like young lovers, complimenting and nagging each other. He asks her to come to live with him, but she refuses-she does not believe it could be as simple as he thinks. She knows Arthur would have to declare war on them. They argue about the unsolvable problem, then embrace. Arthur has been watching them for some time, and acts as if he has just arrived. The lovers try to cover their emotion and guilt. Arthur decides to make a point: he tells the story of his affair with Morgause. He adds that when Mordred was born, Arthur didn't know where he was, so he had all the babies born at that time killed. Mordred, by some chance, survived. Arthur still feels very guilty. Lancelot and Guenever are shocked he has not told them before. He tells them he has told the story because he is afraid that Mordred hates him, and will try to use anything he can against him and his kingdom. Lancelot suggests that Arthur kill Mordred, but Arthur says that if kings behave that way, so will their people, and then there will be chaos. He continues that, in order to have real justice, a king must be able to punish his friends as well as his enemies-anyone who does something wrong. He reminds them that Mordred may one day be King of England. Lancelot says he will kill Mordred if he tries to steal the throne, but Arthur, who still feels guilty about murdering all those babies, forbids it. With this subtle warning to be careful, he leaves Lancelot and Guenever alone.