User blog comment:Safaia Mukade/my questions/@comment-24016459-20131020102820

1- since Zeref created E.N.D. then it's probable.

2- Yes, actually it turns out that there are more than one book : one for each demon. And during the fight vs hades, when he removed his eyepatch he said that Demon Eye comes from the book of Zeref chapter x page x or something like that, if I'm not mistaken.

3-Someone already said the Zeref could have gave it to E.N.D, it looks like the most logical explanation.

4-Who knows :/

5-They thought that he died, they never knew that he was sleeping.