 Ned ( Sean Bean ) confronts Queen Cersei ( Lena Headey ) , telling her that he knows Prince Joffrey and his siblings are not King Robert 's ( Mark Addy ) children , but were incestuously fathered by her brother Jaime . Cersei defends her affair with Jaime , comparing it to the ancient Targaryen practice of wedding brothers to sisters and saying she tried to love Robert , but he refused to love her because he was still in love with Ned 's deceased sister , <unk> . Ned shows Cersei mercy and tells her to leave the capital with her children before he tells Robert the truth . 
