Olaf was a Cimmerian warrior on the planet Cimmeria. As such Olaf was highly skilled in armed combat being capable of throwing an axe at a Jaffa from a distance with great accuracy. As a Cimmerian he is a firm believer in Thor and other Viking traditions, including Ragnarok and does not accept the Goa'uld's claims of divinity.
After the destruction of Thor's Hammer in 1997, Heru'ur arrived on the planet in 1998 with advance troops, and alerted to Cimmeria's vulnerability SG-1 arrived on the planet to render assistance to Olaf and others who'd survived Goa'uld attacks. Though reluctant, Olaf helped SG-1 defend the planet and his people from Heru'ur. While on a scout mission with SG-1, he was captured and tortured for information about the SG-1's arrival through the Stargate, where he unabashedly affirmed his allegiance to Thor while staring down Heru'ur himself, luckily he was soon saved by Colonel Jack O'Neill and Teal'c and the three escaped to the Cimmerian caves to regroup and plan a strategy. He joins O'Neill and Teal'c in an ambush, where he learns of ammunition, which he thinks of as thunder and lightening, in keeping with Norse mythology. A true believer, he says, "you do possess Thor's might. (SG1: "Thor's Chariot")