After his mothers death in 93 ALB, Brandon was quickly ushered in to take her position. This was a decision made by the clergy in private the evening after Evelyn's death. Brandon had been groomed since childhood by the clergy to take over for his mother, and though he did not enjoy the prospect of ruling the Theocracy he did as he was told and took up the mantle.
Brandon's time as the Holy See consisted of many changes and reforms that favored the Church and its rule. By the time he had reached his 40's the Theocracy was almost completely controlled by the upper clergy of the church and Brandon was more of a figurehead.
It was in 113 ALB that Brandon had decided that he would not be this hollow monarch any longer, and began making moves to cut out the upper clergy. This however would be his downfall, as the moment he started making moves against the church, he was assassinated in his sleep. Three days after his death, the church garnered charges against a peasant man by the name of Tyrell Gaja.