User blog comment:Red Eyed Raven/just a quick thought/@comment-4829046-20131212101525/@comment-7418318-20131212172659

You the two timelines mixed up. F-Rogue's timeline only came into being because of F-Lucy traveling back in time.

Originally the Eclipse Gate was built to kill Zeref 400 years in the past, but the gate went haywire and 10.000 Dragons invaded the present, killing pretty much everyone and prompting F-Lucy to travel back.

Because F-Lucy traveled back, the gate was closed before any Dragons came through. In the absence of the Dragons Acnologia turned up, killed Frosch and took over the world. F-Rogue somehow survived, but went mad, invented DMM and because for some reason decided to travel back in time seven years rather than calling the Dragons into his own time (maybe lack on energy in the Eclipse gate, or he wanted to rule an intact world rather than a depopulated wasteland).