User blog comment:FairyRaven/Fairy Tail Chapter 399: Wings of Despair, Review and Commentary/@comment-7418318-20140908160616/@comment-24546844-20140908173529

In truth if Acnologia is going to kill Frost for some reason guess we can expect an heroic sacrifice from Rogue, Sting or Natsu. That would make more sense as everyone sort of already expect Frost being killed soon, and that would also count as ultimate pain. A friend sacrificing his life for another friend to prevent another friend to fall into the darkness. And if it's Rogue the one to make the sacrifice we could see a change in the timeline as Sting would be the one to fall in the darkness.