Orlin, played by Sean Patrick Flanery, is an outcast Ancient. He was forced to remain on the dead planet Velona for breaking the rules of the Ancients by giving advanced technology to the planet's people, who immediately abused it. When SG-1 research the weapon in "Ascension", Orlin is immediately taken with Major Carter and leaves the planet with SG-1, concealed in an invisible form. He shows himself to Carter the next morning at her house, but no-one at the SGC believes Carter's story. Orlin later informs Carter of his backstory, and returns to his former human state in the hope of spending the rest of his life with her, giving up his powers as an ascended. When the NID eventually moves in on Carter's house weeks later, Orlin escapes through a Stargate that he has built in Carter's basement. Back at Velona, Orlin attempts to stop the Tau'ri research of the weapon and is shot by a member of SG-16. The Ancients believe him redeemed and re-ascend him, allowing him to prevent another catastrophe.
Orlin returns in the form of a human child (played by Cameron Bright) in "The Fourth Horseman". He chose this form as it is able to retain a fraction of the knowledge of the Ancients. He tells the SGC of the feud between Ancients and Ori, false promises of ascension and Origin, and how the Ori gain power. He succeeds in developing a line of research into a cure for the Ori plague, but as his gambit with taking a child's form fails, he quickly loses his memory, suffers significant brain damage from holding on that long and is eventually interned in a mental institution on Earth.
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