Bio: Once the lover of Jason Blood, Morgaine le Faye turned her
back on him in the ultimate betrayal: she led him into a painful death
and ultimately ruled in his place. It was for this that, centuries
later, Jason sought out revenge against for her, when she turned up
again with her son, Mordred. After she got a stone that gave the holder
whatever they desired, they began to take back what was once theirs--but
after J'onn read Morgaine's mind, he learned that, though she was giving
and showing him what he wanted with the stone, none of it was real. He
destroyed the stone and Morgaine and Mordred were defeated.
For more, refer to the Justice League Unlimited bio.