Gandar was originally part of House Patrex, but he foreswore his House allegiance and became an interventionist. He had a father, an anti-interventionist whom Gandar and his consociate/girlfriend/partner-in-crime, Cavis, murdered. (PROSE: The Shadows of Avalon)
Two years before the War, (PROSE: Timeline) Gandar and Cavis were instructed by the War Queen to observe/facilitate the transformation of Compassion from Remote to timeship. They orchestrated a war between the humans of Avalon, allied with Britain, and the Fair Folk to the north. Margwyn, one of the disgruntled residents of Avalon, discovered their responsibility for the war and killed Gandar. Gandar hyptonised the avatar of King Constantine (the Red King who dreamt Avalon into existence), attempting to make him attack Compassion and trigger her metamorphosis. When this failed, he tried to trigger it directly by shooting her, but was run through with a sword by Margwyn again. Once the war was over, the sword was removed and he died. He stayed in Avalon instead of returning to his superiors. (PROSE: The Shadows of Avalon)
Gandar was casually sadistic; he nonchalantly caused chaos and carnage more out of fun than to achieve his set goals. He idolised the Master, copying his fashion sense and hypnosis techniques.
Gandar modelled his appearance on that of the Master, with a beard and black jacket and gloves.
After he was first stabbed and killed, Gandar had fair hair, light skin and freckled shoulders.