User blog comment:FairyRaven/Fairy Tail Chapter 371: Tartarus Arc, Part 2: Song Of The Heavenly Dragon, Review and Commentary/@comment-5303512-20140214102756/@comment-4829046-20140214162839

This just gave me the idea that its END is a not a literal book(lol) but rather a creature that is bookish(lol?) So it would be a creature/fusion thingie that can create demons or inject other species and convert them into demons.