In DxD as a Lucifuge

Everyone knows that the Lucifuge Clan have two children, Grayfia and Euclid, but what if they have another son, who is the twin of Grayfia, Grey Lucifuge, whose power matched the Demon Kings, who is feared by the whole Underworld, along with all other factions because of his powers and how easily he kills...... But what if he also had a secret which no one knows, what if he is......