Ea was an Ancient who lived during the latter years of the Lantean's reign in the Pegasus galaxy. She had a child with her mate Atlas and worked with him in the development of the Exogenesis device use in wide scaled terraforming on worlds in the galaxy but were denied testing by the Ancient Council.
Despite this, she along with Atlas, their son and a contingent of scientists travelled to a world to test the device but were unfortunately attacked by the Wraith. They fled in their ship to Lantea but their vessel was destroyed which killed several of the scientists as well as their son. Ea and Atlas escaped in a Puddle Jumper to the city of Atlantis but unfortunately discovered that Moros and the rest of their kind had fled back to the Milky Way galaxy. Ea was critically wounded in the Wraith attack and being unable to penetrate the sunken city's shield, Atlas decided that they were to go into stasis until their kind returned. They submerged the numerous Puddle Jumpers at the bottom of the ocean and slept for thousands of years.
They would be awakened by the Atlantis expedition, however, their inexperience combined with the many years of lack of maintenance had damaged the stasis pods. Atlas's pods memory module would be damaged and accidentally destroyed during the recovery while Ea's was the only one that functioned. When awakened, her mind possessed Doctor Carson Beckett and she became aware of everything that happened. Filled with grief over the death of her mate and the fact that the Ancients no longer existed; she went on a rampage and decided to end the legacy of her people and deny the 'primitive' Humans from using their once great technology. To accomplish this, she activated an Exogenesis device on Lantea in the hope that it would destroy everything on the world. Her mind would expire and end her suffering but not before she healed any injuries sustained by Dr Beckett. (SGA: "Exogenesis")