User blog comment:FairyRaven/Fairy Tail Chapter 465: 400 Years, Review and Commentary/@comment-182.68.37.230-20151209114329

Zeref revived Natsu. Zeref waited for Natsu to become stronger so he can kill him. But if Zeref dies Natsu dies too.

So Zeref revived Natsu and wanted Natsu to kill him knowing that by doing so he will die again.

Zeref has issues.