He is first seen in Brock's flashback when he wants to show his son a secret that he kept to himself for years. The flashback is dated back to 2012.
Gary comes to Brock's store looking for Ash. He is seen wearing the ring of the order and he also has the lost and missing pages of the Necronomicon, or at least copies of it. Gary insists that he needs to Ash, as he believes that he is the only one who can protect everyone from the upcoming evil forces. Brock doesn't believe him and he also states that he hasn't contacted his son in over 30 years. The knight seems relentless, forcing the annoyed Brock to kick him in the groin. Unfortunately for Gary, he was standing next to the stairs leading to the basement of the store. He falls down, losing his consciousness in the process. Brock, in the heat of the moment and thinking he accidentally killed the man, barricades the door and leaves the store.
In the present, Ash and his father, now a ghost, opens up the passage to the basement. They locate the corpse of the ill fated Gary. Before his inevitable death, he painted marks and scratches to the wall with the guide of the pages of the Necronomicon. These writings turned out to be a way to open up a portal between dimensions.