User blog comment:B214/Volume 23 discussion blog/@comment-172.56.17.58-20170417051436/@comment-30924344-20170417235929

Well even when Rias gives up being the Head, Issei will retain his Duke title as a former Lord of the household. Well in issei's case he would still be called Lord Gremory even if he no longer leads the household with Rias. Now about Issei's status, he is already a huge celebrity in the Underworld thanks to his heroic triumphs and the Oppai Dragon show and being a High-Class Devil now who is engaged to Rias [the Underworld doesn't know he propsed to her and the gremory's say the Ruins of Connection trial as their own engagement between the two], but either way its been accepted he is engaged to her. Then his influence and fame will increase once he becomes Lord Gremory. I think Issei's parents will actually get their own castle in the Gremory territory as they will become Gremory's too.