Ellia was a female Wraith who survived a crashed Wraith scout ship, and was found, then raised by Zaddik. Several years later, after some periodic culling on the village, Ellia claimed she did not do it, as Zaddik worked on a serum to halt her dependence on feeding on humans.
When her Wraith scout ship crashed on a planet, the villagers investigated the crash site and saw Wraith. Without taking any chances, the villagers slaughtered them. She and one other Wraith were the only survivors. Ellia, who was only an infant at the time, was found by Zaddik, who took her as his own child, his own wife and son having recently been lost to a fever. For a time, she ate food normally, and was able to survive, Zaddik teaching her about love and companionship as she grew, leaving her with human values, to the extent that she even called him "Father".
However, she soon began to crave the lifeforce of humans, unable to resist the biological need as much as she hated herself for it. Zaddik began to work on a serum to help Ellia, allowing her to feed on him for as long as it took. Eventually, unwilling to continue harming him as she was forced to drain his life, she just lied about the serum working, going out to feed when the male Wraith did, taking his 'leftovers' to avoid attracting suspicion. (SGA: "Instinct")
When Lt. Colonel John Sheppard's team arrived on the planet, and after talking to several of the locals, they were told of the Daimos, a creature that lives in the forest, and feeds on humans from time-to-time. Believing it was a Wraith, the members of the Atlantis team began to search the surrounding forest for what they deduced is a lone Wraith soldier that had survived the crash. While searching in the woods for the Wraith that had been terrorizing the village, the Atlantis team sees and chases Ellia, who inadvertently leads the team to Zaddik'zs home.
Zaddik tells them of Ellia and how he made a serum to suppress the Wraith's need to feed. Dr. Carson Beckett visits Zaddik and Ellia's home to study the serum, and Ellia overhears him mention the Iratus bug retrovirus he is developing to potentially turn Wraith into humans. Ellia hates being a Wraith, and takes the drug without Beckett's knowledge when they step outside for a moment, despite the fact that it isn't yet ready. The retrovirus has the exact opposite effect intended, and increases the effects of the Iratus bug on her DNA.
Acting on pure instinct, now violent and uncontrollable, Ellia mortally wounded Zaddik, killed the male Wraith by breaking his neck, and wounded Sheppard, who was forced to kill her with the aid of Ronon Dex; she took three shots from Ronon's Particle magnum and was still able to remain standing before Sheppard and Ronon managed to kill her. (SGA: "Instinct")