E.N.D.

"Try to surpass me, Natsu. That is...Etherious...Natsu...Dragneel."

- Zeref revealing E.N.D true name.

E.N.D. (ＥＮＤ, in Japanese: イーエヌディー, Ī Enu Dī) (real name: Etherious Natsu Dragneel (エーテリアス・ナツ・ドラグニル Ēteriasu Natsu Doraguniru), is an Etherious created by the Black Wizard Zeref. Originally Zeref's younger brother who died 400 years ago, he was later revived as Zeref's most powerful Demon, thought to be strong enough to kill even the immortal wizard himself.

History
400 years ago, Natsu was born as the younger brother of Zeref, however, he died at a young age alongside their parents, courtesy of a Dragon attack. This caused Zeref to research Magic and its relation to life and death and, much later, with Zeref using his dead body, he was revived as the strongest Demon: E.N.D; whose purpose was to kill Zeref. As E.N.D., Natsu was a Demon specializing in fire, and purportedly discovered a different route that Magic could take when it was still developing and thus created Curses. During this time he also met Igneel, however the Dragon chose not to kill him because he loved him extremely so.

From that point on, Igneel, the mighty Fire Dragon King, taught Natsu how to talk, write, and perform his own signature form of Lost Magic: Fire Dragon Slayer Magic; Igneel ultimately chose, like four other Dragons of that time period, to seal his damaged soul inside Natsu's body and leap four hundred years into the future, recover his strength with the future's high Ethernano concentrations and kill Acnologia. While initially thought to have been abandoned by Igneel on July 7, X777, it was actually the day and year he awoke in the future, like the other four Dragon Slayers.

The departure of E.N.D. from the past also gave rise to many legends about the strongest Demon from Zeref's works, including his creation and leading of Tartaros (when in fact, Mard Geer happened upon E.N.D.'s tome and used it to unify the other Etherious under a single cause and was the one who created Tartaros), and the fact that he was the most vile creation in Zeref's library of works.

Powers and Abilities
E.N.D. is stated to be Zeref's most powerful creation and the only one capable of slaying the Black Wizard. Silver Fullbuster later reveals to Gray that E.N.D. is a Fire-type Demon. This monster is said to be so powerful that even the Dragon King, Acnologia has a fear of this Fire Demon.

Appearance
By what's been seen so far, E.N.D.'s appearance is the same as Natsu's but with Demonic traits such as giant claws. His entire body is covered in violent never ending flames that burn and scorch everything they touch.

Tartaros arc
Believing E.N.D. to be in a "dormant state", Tartaros planned to use a weapon called Face to wipe out all Magic from the continent so that they can gather Curse Power in order to revive their "Master". They would then with their Master return to their creator Zeref.

Mard Geer is seen on his throne holding E.N.D.'s tome as he talks about Zeref's Demons, the Etherious: beings superior to humans. Seemingly reassuring the Master, Mard Geer states that the darkness of Hell's gate will soon appear and eat up the world's light.

Following the destruction of Face, Kyôka reports to Mard Geer, urging him to consider reviving their Master to assist them. However, the Underworld King informs her that there is too much Magic Power present in the world for E.N.D. to properly resuscitate, and, though Kyôka reminds him that that was the entire point of using Face, he states that their plans will still come to fruition.

Some time later, Zeref reappears after Mard Geer's defeat to interrupt the argument between Natsu and Gray on who takes the book of E.N.D. He summons the very book to his hand, claiming that it is something very important that belongs to him. Zeref then praises Mard Geer for his attempts to revive E.N.D and when Mard states that he can realize what Zeref wishes for, the Dark Mage turns his Demon into a book, burning it subsequently. He then vanishes yet again, taking E.N.D. with him as well.

Later, at an unknown place, Zeref ominously remarks that Natsu has to try and overtake him, calling the Dragon Slayer "Etherious Natsu Dragneel".

Alvarez Empire arc
Natsu and Lucy are then captured by one of the Spriggin 12 and just when Lucy was about to be stabbed, The power of E.N.D. is then unleashed inside Natsu. After saving Lucy, Natsu/E.N.D. escapes and starts hunting Zeref only to be confronted by Gray. Gray and E.N.D. mercilessly attack each other without any hesitation. The Devil Slayer and The Fire Demon seemed evenly matched until they were stopped by Erza. Erza made the two come to their senses and Natsu's demonic transformation diminishes.

Gallery
File:E.N.D. vs. Gray.png|E.N.D. vs Gray Fullbuster File:Demon Natsu destroy's Gray's projectiles.png|E.N.D.'s Claws