User blog comment:Stone Roger/Natsu and Zeref have somekind of relation?/@comment-92.21.71.76-20130504112857

Read the manga; during the grand magic games it is revealed there is a portal to go 400 yrs back in the past, they said it was supposed to be used to stop Zeref from being immortal by going in the past and killing him or used to kill the 1000 dragons.