User blog comment:B214/Volume 23 discussion blog/@comment-185.112.105.215-20170419115644/@comment-31137559-20170421014730

What if Millicas marries a reincarnated devil then? People just assume that Rias is allowed to marry Issei because Zeoticus and Venelana thought that they had Millicas as a back-up. What's the whole point of Issei becoming a noble then? What's the whole point of him being engaged to Rias and becoming a Gremory in the future? What's the whole point of him being a high-class devil? What's the point of him basically being lord of the castle in the future? What's the point of him even being a devil in the first place? Just because of something that was said at the beginning of the series about how noble pureblood devils can only inherit the house which doesn't hold true much later in the series. Issei wouldn't even be allowed to marry Rias since high-class pureblood devils from noble families can only marry high-class pureblood devils from noble families to maintain good relations between the noble households.