When a Prior visited Tegalus and offered Rand a powerful satellite weapon capable of conquering their enemy, the Caledonian Federation, Pernaux recognized that the power of the Ori allowed no alternative but to accept Origin, and he supported Nadal's decision to use the weapon. He believed that Earth was largely responsible for the recent civil war and devastation on his world, and when Jared Kane attempted to disable the weapon with the help of SG-1, Pernaux was convinced that Kane and Dr. Daniel Jackson were Caledonian sympathizers and spies.
However, Pernaux had known Kane for many years, and he began to consider Kane's warnings, especially when Nadal's paranoia drove him to order the destruction of the Caledonian capital. Pernaux shot and killed President Nadal to shut down the weapon, though he was shot in the process. His actions prevented the return to global war, but only temporarily. Pernaux succeeded to the presidency and began negotiations with Caledonia, but soon afterward, the talks broke down, warfare resumed, and Rand and Caledonia supposedly destroyed each other. (SG1: "Ethon")