User blog comment:Miskos3/Fairy Tail 536: The Flame of the Dragon's Roar, Review/@comment-130.105.140.184-20170522124332/@comment-24367018-20170523104047

Well, the movie was made and designed to flesh out story aspects that Hiro couldn't include in the manga. So I suspect that if the anime does return, then it hypothetically could cover some of the backgrounds of the 12.

Don't forget though, of the Seven Kin of Purgatory and the Nine Demon Gates, only Ultear and Meredy's backgrounds were given anything remotely akin to fleshed out backgrounds.