The Once and Future King Book 4, Chapter 10

Mordred has become the leader of the popular party, the Thrashers. Mordred continually pushes Gawaine to hate Lancelot by reminding him of Gareth and Gaheris. Mordred has become subtly stranger in the past few months. The Pope has brought peace, forcing Arthur to take Guenever back, and allowing Lancelot to bring her to Camelot and to leave safely. But after that, there are no orders concerning Lancelot, and Gawaine has determined to kill him. Lancelot and Guenever arrive during a ceremony watched over by a bishop, and Gawaine and Mordred sit with the King. Lancelot claims that Guenever is innocent, and he will prove it by fighting anyone but Arthur or Gawaine. He says that Guenever called him to her room that night and, before he knew why he had been called, Mordred and the others were beating on the door, calling him a traitor. Gawaine refuses to accept this, saying that he will never forgive Lancelot for what he did to his brothers and to the King. Lancelot tries to appeal to Arthur, but Arthur, trying to be just and not knowing what to do, allows Gawaine to take over. Gawaine banishes Lancelot to France, and tells him that he will pursue him there. Painfully, Lancelot says good bye to Guenever and tells them all that he will be there to serve Arthur if he is ever needed, as he has been for his entire life. It is the last time he, Arthur and Guenever are ever together. Everyone in the room is humbled, and frightened of what might come of Mordred's ambitions.