He showed the people of Velona how to construct an Orbital weapon to defend themselves against the Goa'uld. After the Goa'uld threat had been averted, the Velonan people began to plan the conquest of other worlds. The other ascended beings came and wiped them out to "correct" Orlin's mistake—sentencing him to live alone on the desolated planet as punishment.
Eventually, SG-1 came to the planet. Orlin attempted to connect with Major Samantha Carter, but his ascended form overwhelmed her. He followed her through the Stargate to her home, where he appeared to her. He eventually took human form in order to be with her. Upon learning that Stargate Command intended to test-fire the weapon on Velona, he built a miniature Stargate using various parts ordered online and from Carter's toaster. He was shot by Lt. Colonel Albert Reynolds while attempting to disable the naquadah generator powering the device, knowing that the device was set to overload to provide the necessary power. The others allowed him to ascend again and he used his powers to take the generator to a safe distance while destroying the weapon permanently. (SG1: "Ascension")
Five years later, Orlin returned to assist Stargate Command in their war against the Ori. He took human form once again, this time as a child to retain as much of the ascended knowledge as possible. After informing them of the true motives of the Ori which included the revelation that the Ori sapped power from those who worshiped them while also not granting their worshipers ascension, but simply a meaningless death, Orlin aided them in the creation of the Prior disruptor and a cure to the Ori plague. Unfortunately, the amount of knowledge Orlin had managed to retain was too much for his brain to handle, and large portions of his brain cells died from trying to retain the knowledge. Left with severe brain damage and unable to return to his Ascended brethren, Orlin was later put into a nursing home on Earth, unable to remember his past life with Sam later visiting him. Though he was unable to finish work on the cure, his work was instrumental in engineering a cure from the immunity Gerak granted to the SGC personnel through the use of his Prior powers. (SG1: "The Fourth Horseman, Part 2")
- British-born Canadian actor, David Hewlett was originally scheduled to play Orlin but couldn't accept the role due to a scheduling conflict which meant that the role went to Sean Patrick Flanery instead. Hewlett would later appear in the Stargate SG-1 series as Dr. Meredith Rodney McKay before becoming a series regular on the spin-off series, Stargate Atlantis and then having a guest appearance on Stargate Universe.