User blog comment:IamJakuhoRaikoben/Chapter 513: Flower Circle, Review./@comment-5672982-20161205171459

Interesting to know about Irene having been the former Queen of Dragons. While this could explain her extreme power and magic potential, she doesn't seem to have a connection with Acnologia, or better said, Acnologia doesn't seem to know her, or recognized her to be the former Queen of Dragons.

If so, maybe its because there was a legit King of Dragons way back before Acnologia rose up and slaughtered almost every dragon in the far past, including the former King, and took the King's title for himself. Irene on the other hand, was the wife/mate of this said King, and was one of the few rare Dragons that survived from the Dragon Civil War, eventually joining up with a still young Alvarez Empire back in the day.

Of course, this is just a theory, but if true, that would explain a lot.