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|Out of universe information|
Chaya lived on Proculis when she was mortal and eventually ascended with the other Lanteans. Chaya was among those ascended who found it difficult to leave her mortal life behind, when the Wraith approached Proculis, she lashed out with her mind and destroyed the Wraith. She was punished for this and exiled, to protect Proculis, and only Proculis leaving other worlds to be destroyed by the Wraith. In 2005 some Wraith Darts came to Proculis and Chaya destroyed them, bringing attention to Major Sheppard's team who came to investigate, believing it to be a weapon that destroyed the Wraith ships. They met with Chaya and asked to allow other people to come to Proculis to be protected, however Chaya and the planets monks communed with "Athar", their god, and informed them that she would not be able to protect them.
They convinced Chaya to return to Atlantis, in an attempt to further convince her to allow refugees from other worlds to come and live on Proculis. Chaya was examined by Dr. Beckett who found her to be in prefect health. Major Sheppard gave her a tour of Atlantis and she activated a console, indicating that she had the ATA gene. McKay grew suspicious of her and ran some tests. Chaya discovered what she was doing and revealed herself as an ascended being. Chaya became aware of a Wraith attack on Proculis and returned through the Stargate and destroyed them. Sheppard followed her and she revealed that her punishment was to only protect the inhabitants of Proculis and no one else. After this they performed a "sharing". (ATL: "Sanctuary")