User blog comment:B214/Question and Answers/@comment-37.231.49.206-20140110200545/@comment-24098614-20140111013043

I think that is highly unlikely to happen, and Rias wouldn't be very happy about this at all because the other girls she can accept but your best friend going after the one you love could create a hostile relationship, and Sona and Rias are rivals in terms of who is the better Clan. My favorite one would be Serafall if I were to pair up with Issei but Sona creates hostility between the two Peerages.