Gaius Septimus was the son of Gaius Sextus. He was killed in the First Battle of the Calderon Valley, fifteen years before the events of Furies Of Calderon. His death is the reason for the succession crisis in Alera because he was believed to be the only heir. In actuality Septimus married Isana in secret and they had a son, Tavi.
Septimus began furycrafting at the age of five. He studied at the Academy in his youth. During this time, he was close friends with Aquitainus Attis and later befriended Antillus Raucus after a year of fights and difficulties. This group also came to include Septimus's future singulares, most notably Araris Valerian.