Before Zeref and Natsu were brothers and then some dragons came and killed Zeref's family. Zeref was an orphan and he went to an academy to learn about life and death. He made many creations like the R-system which resulted in him being banned from the academy and being cursed by a god. Now everything that came close to him dies and he was labeled as a dark wizard. He kept on killing people and all he wanted to do was die. then he created etherious in hopes for killing him which eventually led to him 'making' natsu as END.
