User blog comment:FairyRaven/Fairy Tail Chapter 435 & 436: The Cry of Victory & Memoirs, Review and Commentary/@comment-5303512-20150518115901

This is just a guess for what E.N.D.'s personality is like, when he was create he probably hated Zeref because he made from his little brother's body and is having Identity/Existential Issues and left Zeref to suffer his cursed immortal life. He loathes all things that are bound by the concept of "Life".