User blog comment:FairyRaven/Fairy Tail Chapter 324: The One Who Closes The Door, Review and Commentary/@comment-1776824-20130322143738/@comment-84.113.52.218-20130322201611

That would be a nice plot twist I also thought about already.

Someone (maybe Zeref or the Grimoire Heart remnants?) notices future Lucy going back in time, but are unable to prevent it. Since they are worried that future Lucy might succeed in preventing their plans in the past, they manipulate future Rogue to think it was all Lucies fault. He then is allowed to travel back in time (with him believing he did it by himself) to eliminate Lucy, which would also eliminate the future Lucy (he didn't even know existed).