User blog comment:FairyRaven/Fairy Tail Chapter 426: Black Heart, Review and Commentary/@comment-25111584-20150401185614/@comment-24.90.189.198-20150402200755

Ok well second problem with your timelines, lucy comes back after everyone is killed in her timeline.

So it has to be more likely that the dragon invasion happens after Gray kills Frosch. Dragons kills everyone except now evil rogue. Evil Rogue then decides to go back even further than Lucy did to control how the Eclipse Gate is used since in his timeline he is the last one standing and thinks he can become emperor in this timeline if he wins before everyone is killed.