User blog comment:Derax-Pagani/Chapter 507: Voice/@comment-4449950-20161028023156/@comment-2214433-20161028131056

Her loyalty to Zeref could be explained if he was the one to grant magic to her. Acnologia even said she was taught by Zeref.

Unable to live without magic, Knightwalker searched through Edolas and found some random reserve of magical power which wasn't sucked up by Anima and used it to travel to Earthland. Found by Zeref, he took her in and taught her.

Perhaps we could also look at the fact that Irene seems to be using her staff every time she performs any magic. Perhaps it was created by Zeref to grant power to those without magic.

Damn, I should write fanfics.