User blog comment:B214/Volume 23 discussion blog/@comment-77.188.250.151-20170426212117/@comment-30048084-20170427182430

Issei's Queen will not be a devil the queen is the strongest piece so she would have to surpass Ravel for it to seem realistic. I doubt there are many Devils that can surpass a Phoenix(Phenex) unless the Devil in question possessed multiple unique abilities for example Worthlessness(Belial), Hole(Abaddon) and another ability.

A Dragon King(queen) or another being that is off the charts is pretty much the only choice for Issei's queen.

Dragons are Prideful I agree it is not like they cry, need counsellors, obsess over Panties and complain about having to do anything. I think that the dragons of DxD's concept of pride is quite different from what we think of when we think of pride.

Tiamat becoming Issei's Queen is quite logical, she becomes the Queen of What I guess will eventually be considered the third God-Class Dragon. Plus a Queen is not a mere 'servant' they are the right-hand being of the King. The queen also gains the ability to use the traits of all the other pieces which would make her stronger.