How did Zeref get cursed? Some people think it was Mard Geer. I'm so sorry to trample on that thesis, but Zeref created Mard Geer and it is said that E.N.D, I mean Natsu, is the strongest demon who so happens to be Zeref's brother.
I was thinking that maybe Natsu cursed Zeref, but Natsu was out searching the world for his foster parent Igneel, right? Then I thought maybe Mavis cursed him? Not true either, because in the little flashback, Zeref already had the Death curse when he met Mavis and Mavis is way too sweet! Yeah some of you may be thinking "Mavis is the Fairy Tatican and she has won many wars" but I'm a Zervis shipper, sorry!
Then that had me thinking: does anybody remember that crucial detail (it happened fast but not fast enough) that Zeref 'lived' with all the monks, so maybe they cursed him? So then I did my research and some monks are, umm I don't wanna type evil, umm BAD. Most of the monks back then worshipped god. I watched a lot of religous anime! So that was soon to be proven wrong.
Yep, I can't answer my own question. I wonder if Hiro Mashima wanted us to think this?