So well watching the old Fairy Tail series, you get the vibe that Zeref is a god of destruction, summons demons and wants to rule the world then later on before they are all trapped on the island Zeref did not fight back and wanted to harm anyone.
Later after this I think around the Arena series Zeref states the world rejected him and how he now rejects the world.
Well watching Fairy Tail Zero, what I assume and what as been said, Zerefs power is strong because he does not want to harm anyone and its the curse. So far he seems to only want to protect people however I am only at epp 099 currently and was said something drastic is about to happen.
If you have seen Fairy Tail what do you think.