One of the big reveals in Fairy Tail was that not only was Natsu E.N.D., but he was also the brother of Zeref, the main antagonist of the series. The two had been tied together for much of the series and their battle always seemed like it was going to be the one that wrapped up Fairy Tail.
While it was a bit of a surprise at the time, looking back, there were many clues that the two were related. A few are minor, but others make the reveal pretty obvious.
10 He’s Wishing To See Natsu The First Time He’s Shown On Screen
While innocuous at the time, Zeref stating he wanted to see Natsu the first time he’s shown on screen is a major hint to how tied together they are. Why else would he want to see Natsu? It couldn’t be that he was a Dragon Slayer because Wendy and Gajeel were both on the island at the time as well. There was nothing else that could have bonded them together, not even the great feats that Natsu had managed to pull off up until that point.
9 Stating That Natsu Has Grown During Their First Skirmish
Even more than Zeref’s desire to see Natsu, his proclamation that Natsu had grown was another dead giveaway. Despite how long Zeref had been alive, there was no way he could have been following Natsu’s progress for years. At the time, it seemed like Zeref was talking about Natsu’s growth as a mage. Looking back, he was clearly talking about how much he’d grown both as a person and in the physical sense.
8 Zeref Never Intentionally Attacking Natsu Or Fairy Tail On Tenrou Island
Despite the attack that was absorbed by Natsu’s scarf, Zeref never intentionally tried to fight Natsu or any member of the Fairy Tail guild. His presence was mostly spent moping about how the world was rejecting him.
In reality, it seemed like he was on Tenrou Island for both Mavis and to see how far Natsu had come. That’s shown by his disappointment that Natsu was not yet prepared to kill him. If Zeref really wanted to, he could have killed almost everyone on that island.
7 The Anger Zeref Had Towards Hades Was More Than Distaste For His Actions
The brief monologue Zeref had with Hades seemed to be a way to show that Zeref hated those who destroyed indiscriminately, that he wasn’t the bad guy the series made him seem to be at first. While that’s true, it wasn’t the full story of why he confronted the former Fairy Tail Guild Master. Zeref blamed him for Acnologia’s arrival and the inevitable destruction of the island, and given that his brother would be among the casualties, it’s not much different than Itachi going to Konoha to put the fear of god into Danzo.
6 Zeref Shed A Tear At The Destruction Of Tenrou Island By Acnologia
The end of the Tenrou Island arc was shocking and could have had far more emotional weight than it ended up having. Acnologia’s arrival and complete decimation of not only Fairy Tail but Tenrou Island was an stunning moment. The whole arc helped establish the pecking order in-universe, putting Acnologia and Zeref on another level. It also showed the level of sadness Zeref had for the results, shedding a tear when he thought that was the end of Natsu. He never showed that same emotion for anyone aside from Mavis.
5 The Amount Of Times He Lingered Around Fairy Tail After The Tenrou Island Arc Was Always Suspicious
While Zeref and Mavis’ relationship was less of a mystery, it was still odd how often Zeref lingered in the background of events that involved the Fairy Tail guild. He always seemed to be around, keeping tabs on Natsu.
Part of it was always to see Natsu’s progress, making sure he would be strong enough to kill him, but the other half had to be watching his brother grow. He couldn’t take a role in Natsu’s life as he’d like to, supplementing it any way he could.
4 The Battle Between Natsu & Zeref Was Built Up As Destiny
The battle between Natsu and Zeref was hyped up from the very beginning. It’s all Zeref seemed to care about and nothing else mattered more, even Mavis. Almost every time he showed up, Zeref would make some passing reference to this fated conflict, be it internally or externally. It felt no different than Sasuke and Itachi’s destined battle between brothers in Naruto. To Fairy Tail‘s credit, the story held off on revealing their familiar bonds as long as it could, but it was always obvious why Zeref wanted Natsu to be the one to kill him.
3 The Fact Zeref Knew So Much About Natsu
Sure, Zeref had been around for ages, seeing the rise and fall of many empires. That doesn’t explain how he seemed to know so much about Natsu. He knew intimate details, such as E.N.D. and Igneel’s mission to destroy it. It’s a wonder why none of the characters put two and two together, or at the very least got curious about how Zeref knew so much. It was always obvious that the two were either related or that Natsu was a creation of Zeref’s.
2 Zeref’s Magic Grew Uncontrollable Around Natsu
The biggest caveat to Ankhseram Black Magic was that it could only be controlled by someone who’d grown apathetic to human life. It’s how Zeref was able to be the emperor of the Alvarez Empire. He didn’t care about any of them, seeing them all as pawns in his schemes of bringing a great war to the world. That wasn’t true when he saw Natsu. The magic would flare up, lashing out at random because no matter what Zeref told himself, he cared about his brother.
1 The Entire Monologue During The Avatar Arc Spelled It Out To The Audience
If there was ever any doubt about their ties together, the Avatar arc decided to make it clear as day. Rather than to build up to the reveal during the arc, it was practically spelled out for the audience in a monologue that Zeref delivered while talking to a book. He explained all of the important facts of his past, including his immortality and his struggles to find a way to bring his dead brother back to life. It was an odd decision, sapping much of the mystery away.