Simon was a villager in a pre-Chaucer Middle Ages Christian society on a planet ruled by the Goa'uld Sokar. He was introduced in the episode, 3.08 "Demons".
Simon watched as SG-1 removed Mary, a young woman left under his care, from her chains as she awaited the Unas who came through the Circle of Darkness (Stargate) regularly to retrieve human "sacrifices" for his lord, the Goa'uld System Lord Sokar, who was impersonating the Devil (Satan). Simon befriended SG-1 and the team decided to help free these people from the Unas "demon" by staging an ambush when the Unas returned to the planet the next morning. Unfortunately, SG-1 was considered evil and unclean by the village's leader, the Canon, who had them captured and chained. Simon tried to tell the Canon that SG-1 were there to help them, but he was unsuccessful and the Canon implied that he would be among the next to be sacrificed.
SG-1 and Mary were chained to posts in the courtyard to await the Unas the next morning. Simon followed them when the Unas started to take them on the long journey to the Stargate (11 kilometers from the village). Simon helped fight off the Unas to free Mary and SG-1 and was injured in the leg, but managed to kill the Unas with its staff weapon. The symbiote jumped into the Canon who had also followed them. Jack killed the Canon while he was seeing them off at the Stargate and Simon said a form of the Catholic prayer for Suffering Souls over the Canon's body.
Simon promised that he would bury the Stargate so that no more demons would come to his village again.
--DeeKayP 19:05, 24 Apr 2005 (PDT)