User blog comment:LastationLover5000/Fairy Tail 424 - In Which Gray Shops For Hair Gel (Avatar)/@comment-5497946-20150316200725

Betcha the mark turned him full on demon, Dragon slaying magic eventually turns ya into a dragon if you overbath yourself in their blood, Demon slaying magic turns ya into a demon which in turn is vulnerable to the will of zeref. Lesson of the day get your mark checked before you turn full on evil!