User blog comment:Wrath022/Chapter 516: The Truth About Enchantment, Review/@comment-5303512-20161227040743/@comment-5303512-20161228143315

WTF? Brain and Natsu are not the same person, it's not like they are like conjoined twins or anything.

With Laxus, Dragon Slayer magic had confirmed that it does alter one's personality to make them more aggressive and violent at times, just as Brain's personality can change to something more psychotic, but that does not make Zero any different than Brain since they are the same person, and like Natsu's personality changes to something instinctive and hateful.