User blog comment:Miskos3/Fairy Tail 522 & 523: Gray's Trump Card & Is Destiny Burning, Review/@comment-130.105.140.184-20170218075015/@comment-1359322-20170219042029

If your dog shit on your girlfriend's shoe, it means you're the one who shit on her shoe then.

That's why i don't see Zeref as the one who caused the killings. Zeref never said that the Etherious must kill humans nor did he implant an instinct to kill humans in them. The Etherious themselves did that on their own free will. If there is any fault with Zeref, it's that he let the Etherious do what they want uncontrolled.