Prologue

In order to become an S-Class Mage, Elfman and his partner, Evergreen, continue to participate in the second trial. However, they find it difficult due to the island's strange and aggressive creatures. As they are being chased by a wild beast, Elfman and Evergreen fall down a hill and finds a strange guy. Elfman and Evergreen are confused with the guy's appearance since only members of the guild are allowed in the island.

Elfman charges towards the guy who tells him to stop and promises to leave the island if they don't come near him. Suddenly, the guy feels something coming and calls it the Death Preying. He is then engulfed by a black wave that begins to expand, killing everything that it touches.
Natsu arrivesNatsu suddenly arrives and pulls Evergreen and Elfman away from the orb. The guy notices Natsu and his eyes begins to be filled with tears while Natsu demands to know who he is.

While Elfman and Evergreen expresses their surprise with Natsu's arrival, Happy suddenly arrives and notices that the surrounding trees have withered. Seeing the effects of the mysterious guy's Magic, the group concludes that he is not an...

At some point in history Zeref witnessed many people dying in war. He also became cursed and helplessly started to take the souls of others without his own intention.
He is known to be from ancient times and presumably wields nearly unimaginable power, as even the strongest Mages shiver upon hearing his name. Ultear mentions that he alighted on an ancient land, mastered black Magic, gave birth to tens of thousands of demons, and threw the world into chaos.

Because of this, Zeref was sealed away for centuries. However, one day he apparently managed to set himself free despite the fact that Grimoire Heart did not collect all the keys to his prison, although the darkness inside him remains sealed. Apparently, the slumber made him a very kind person as he cares for others' safety now and wishes to be destroyed once and for all. At some time in the past, he apparently learned about Natsu and realized he could kill him someday. It can be presumed that he later wandered by himself, eventually finding Tenrou Island and deciding to stay there in seclusion, completely unaware that the island falls under the jurisdiction of the Fairy Tail Guild (and that no one else was...

Zeref was said to have been the darkest, most evil Mage in the history of the Magic World. He lived up to this reputation by mastering the Black Arts of Magic and creating demons, which continue to wreak havoc.
In the modern age Zeref isolated himself and seems to have a gentler, melancholic personality. He is often seen behaving calmly in extreme situations. He apparently wishes to die to atone for all the sins he has committed and may commit in the future, and when he realizes that Natsu isn't ready to kill him yet, he breaks down in tears. He commits incidents without his own knowledge or out of his own control, as seen when he kills Zancrow.

However, he is still shown to be extremely intimidating when angry, and will not hesitate to punish those he believes to be evil, such as Grimoire Heart.


source: http://fairytail.wikia.com/wiki/Zeref