Sole survivor of a long-extinct civilization who were almost entirely wiped out by Thalan's people. She fought against her mortal enemy Thalan for years ... until they were the last two fighters left.
Phoebus survived in a stasis pod in the Kohal System long into old age, and was retrieved by John Sheppard's Puddle Jumper and taken back to Atlantis. Her consciousness, stored within the pod, downloaded itself into Elizabeth Weir (who happened to be in close proximity) and took control of her body.
Phoebus awoke in Atlantis's medical bay. Pretending to be benign, she told the team that she had a limited amount of time before her consciousness was erased from Weir, and that the other pod held her husband, Thalan. To drive her lie home Phoebus faked Dr. Weir's personality (using her memories). She convinced Colonel Sheppard to allow Thalan, who was as old as she, to migrate into his body so that she could properly say goodbye to him. Sheppard agreed, but unfortunately, once Thalan had gained control, it was obvious that the two were the coldest of enemies.
Phoebus and Thalan, now in Weir and Sheppard, went on a rampage through Atlantis in an attempt to annihilate each other for the vindication of their respective races. After a rampage threatening many lives the two were caught. Phoebus survived partially through the night before Weir's body convulsed, expelling the consciousness completely.
The Long Goodbye - Phoebus, a blood-thirsty soldier, is resurrected in the body of Dr. Wier, whom she uses as a pawn to kill her true target in the body of Colonel Sheppard.