User blog comment:Stone Roger/Natsu and Zeref have somekind of relation?/@comment-101.174.197.171-20140430072854/@comment-7418318-20140430082713

If Zeref had only known that whimp Dragion, he'd never have expected Natsu to be the one capable of defeating him in the first place.

Also if Zeref had gone to Edolas, he would have most likely stayed there. Without eating an X-Ball his magic doesn't work there and thus his powers can't go out of control to kill someone by accident. Edolas would have been like paradise Zeref in the period between 400 years ago and his "re-awakening" due to Grimoire Heart's actions.