User blog comment:Maxx-DxD/Issei's becoming a King./@comment-65.48.242.237-20140828221656/@comment-220.233.78.134-20140829063604

he would still be classified as part of Rias's peerage even if he becomes independant like the former dragon king he become a king but was also a part of a peerage so you can have a lot of peerage linked back to one of the major families by this method and because he wants a huge harem he will need his own peerage but because he is under Rais comand she can use his peerage as well.