User blog comment:B214/Question and Answers/@comment-23789372-20131023004504/@comment-1359322-20131023045815

Actually no, even if Issei becomes independant, Issei will still be Rias' Pawn. Much like how Tannin is still Mephisto's Queen even after he becomes an Ultimate-class Devil and gained his own peerage and territory. In fact, Issei becoming a High-class Devil and getting his own peerage will make it better for Rias, since her future husband isn't weak.