Gabriel was once one of God's mighty angels in heaven. He was known as the "Left Hand of God" and served as a messenger of God. He appeared to the prophet Daniel, revealing secrets about his future. He also appeared to Zacharias and to the Virgin Mary, foretelling the births of John the Baptist and Jesus. He was also one of the four archangels whom God sent to deliver his messages to his prophets. Gabriel was also the angel sent to destroy Jerusalem.

At some point, Gabriel descended to earth and took on living flesh, becoming human. During his time on earth, Gabriel fought many great battles. At some point near the 1460s, he was under the service of the Knights of the Holy Order when he met Count Vladislaus Dracula, with whom he became close friends. However, during a great battle, and for reasons unknown, Gabriel murdered Dracula in 1462. For this crime, God erased Gabriel's memory (though the video game claims that Dracula had broken the oath of celibacy of the Knights of the Holy Order and when the woman he loved was banished and killed he tried to bring her back to life with dark magic which forced Gabriel to kill him and unable to deal with the guilt, Gabriel asked God to erase his memories which God did).

Gabriel spent the next 400 years wandering the earth until one day after a battle, again with no memory, he was found half-dead crawling up the steps of the Vatican.