User blog comment:IamJakuhoRaikoben/Chapter 415: And It Shall Become Your Will To Live, Review./@comment-5288632-20150112160243/@comment-9595671-20150115011726

I think we're all wondered what the OS said to Jellal's proposition, since no member of Tartarus would ever ally with Fairy Tail due to what Mard Geer described about why they follow Zeref they're the only way we get former villains in this arc.

At the same time the Magic World has to deal with the Magical Council's death, the fact that the Balam Alliance has pretty much been shot apart, Magnolia's damage from Tartarus and Acnologia, Zeref having possession of END and how the reduced magic caused various problems and everyone most likely will be weakened for a bit.