User blog comment:B214/Volume 22 spoilers/@comment-73.46.6.122-20160818191943

New idea! Issei’s queen (Bina Lessthan) could be a member of the astaroth family (maybe even the daughter of Ajuka Beelzebub (I don’t say the former queen of diodora’s peerage because of the fact she was corrupted beyond repair along with the other peerage members and we have no idea how many survive the battle in volume 6 (of course we already know the knights are dead seeing how freed said he ate them), mainly caused were not certain if they were using the retiring system or not)). Let’s face facts, after the whole incident with that psycho diodora, which caused great damage to the astaroth family’s reputation (so much they’ve lost a lot of their privileges), they probably wanted to find some way to redeem themselves, and what better way than to give on issei (the hero of the underworld and an indirect victim of diodora’s schemes, asia was the real victim) a powerful queen. And most likely she could be like rias (didn’t want to be with someone who didn’t see her as a regular person), sona (doesn’t want to be with someone who wasn’t as smart as her), and/or maybe like seekvairia (a smart no nonsense type of girl as we’ve seen so far) in personality, as she did say that she wanted to test his caliber as a king, which means she probably doesn’t want to be subservient to anyone she perceives is weak.