Aeril fen Derngil served as the High King of Battania until his mysterious disappearance some time before the Battle of Pendraic. During his life, he took the young Caladog fen Gruffendoc under his wing and adopted him.
Aeril's clan members grew suspicious that Caladog could have played a role in the former High King's disappearance. It was Ergeon, Aeril's brother and clan chieftain, who convinced his kinfolk to support Caladog and the strong Battanian monarchy their family had always supported.
Her niece Taseil is implied to be a fen Derngil kinswoman.