ok how's this.
Lelouche is Arthur, and Suzaku is Lancelot. Since they fight over her, Nunnaly is Guinevere. The Knights of the Round are just that.
Now, if Anya is standing in for Mordred, she will mortally wound Lelouche at the end of the series. Unless, of course, we are post myth and this is where Arthur comes back to take his rightful place as the leader of all humanity. In which case, even if Anya used to be Lelouche's Knight, she will be killed at the hands of who she once served. If this is to be achieved in the storyline, it will be established in the next 3 episodes.