Weiss was a hologram programmed by Hirogen engineer Donik. He was programmed to be a typical Starfleet officer, using information from computer data obtained from the USS Voyager in 2374. He had skills in some scientific pursuits, including anthropology and geology.
Like many holograms used by the Hirogen, Weiss was constantly targeted as prey by Hirogen hunters. His time with the Hirogen made him bitter and bloodthirsty; he killed forty-three Hirogen while escaping them in 2377. Soon thereafter, he was serving aboard Iden's ship, the Olarra, as tactical officer. He beamed down to Ha'Dara with several other Olarra crewmembers to take revenge upon Hirogen hunters, turning them into prey. Along with his colleagues, Weiss was transferred into his ship's database by B'Elanna Torres and Kejal. (VOY episode: "Flesh and Blood"; CCG set: Holodeck Adventures)