Orem Vacker is Alvar, Fitz, and Biana's many-greats-grandfather and the son of Luzia Vacker. He is also a Flasher who puts on light shows when eclipses occur. In Book 1: Keeper of the Lost Cities, Elwin calls him one of the best Flashers in the Elvin world. Not much is known about him, since he is a minor character and is only mentioned in Book 1: Keeper of the Lost Cities, Book 2: Exile, and Book 7: Flashback.
Orem Vacker provided Luzia Vacker's DNA to open the door to the troll hive since he had already known that his mother, Luzia Vacker had been helping the trolls and their hives. Alvar Vacker gossiped to Keefe that Orem Vacker and his mother (Luzia Vacker) didn't get along.
Orem Vacker gives his light show on the annual solar eclipse festival before Sophie teleports in with Silveny. Sophie missed this show because she was the finale after Orem Vacker's amazing light show.
Orem is described as having neatly cropped hair and bronze skin.