Eren is the main character ofAttack on Titan, one of the mostpopular anime ever made. When he was first introduced, he was a child who wanted to join the Survey Corps, a branch of the military that fights humanity’s predators, the titans. After they broke into his home and one of them ate his mother, Eren joined the 104th Cadet Corps and trained alongside his new comrades.
Related:Attack On Titan: Levi’s Best Quotes, Ranked
After they graduated, Eren discovered that he could transform into a titan and became the Survey Corps' greatest weapon. Another soldier from the 104th Cadet Corps, Annie, also had this ability but used it to attack the Survey Corps, leaving Eren to have to fight her at the end of the first season. He’s changed a lot since then and here are some of the clearest things that prove it.
Updated July 20, 2025 by Ritwik Mitra:Attack on Titan is a series that has gone through several twists and turnssince its inception, with the plot revolving around man-eating monsters before spiraling into tales of political intrigue and the wasteful nature of war as a whole. The show itself is a dynamic spectacle that deals with several mature elements, executing them in a truly impressive manner and proving why the show deserves all its plaudits and more.
The most entertaining part of Attack of Titan without a shadow of a doubt has been the protagonist Eren Jaeger himself. The character has wasted no time in showing just how much of an enigma he really is transforming by leaps and bounds ever since the advent of the first season. Here are some of the most notable and impressive ways he’s changed from the young angry man viewers were familiar with in Season 1.
17He Acquired The Powers Of The Founding Titan
Eren acquired the powers of several Titans after devouring them, but the manner in which he got the powers of the Founding Titan was something else. After being brought over to the Paths, Eren decided to betray his brother Zeke and appealed to the individual within Ymir, removing her shackles to the royal family in the process.
He reasoned with her and commented on how lonely she must’ve been all these years, prompting an emotional reaction from Ymir who decided to help Eren out in his genocidal quest. It was a powerful moment with Eren turning into the nightmarish Founder Titan and unleashing a wave of Colossal Titans to destroy the entire world.
16Anger Stopped Being His Only Motivation
There was a time when Eren simply couldn’t control his anger, which is understandable given the trauma he went through as a child. The brutal loss of his mother unlocked a well of anger within him that he accessed to fuel his motivations, from joining the Survey Corps to using the powers of the Attack Titan to bolster humanity’s war against the titans that sought to eat them.
However, over time, Eren calmed down and realized how messed up the world really was. His anger at the world diminished after realizing just how fabricated and unnecessary these conflicts really were, causing him to develop some twisted ideologies thatultimately led to him becoming the series' main villain.
15He Gained An Understanding Of Both Sides Of The Conflict
After realizing that humanity was actually in a conflict against each other, with the Titans being nothing more than byproducts of this aggression, Eren’s mind was warped, and he had a lot of thinking to do. Thinking that everyone across the sea was his villain, Eren decided to live amongst the Marleyans in secrecy and figure out what drove this hatred.
This led to him realizing that there was nothing inherently bad or good about either the Marleyans or Eldians. Both groups had been pushed to the brink because of acts carried out in the past, even though they were essentially the same people. It’s this realization that led to Eren calming down… although it did lead to another warped thought entering his mind that ultimately led to Eren justifying the very act of destroying the entire world!
14He Killed A Titan Without Transforming Into One
Eren has killed more than anyone else in the franchise, but he has mostly used his titan abilities to fight his enemies. Because of that, it wasn’t until the second season that he would kill a titan the way he was trained to in the 104th Cadet Corps.
Related:Attack On Titan: Every Opening Song And Intro From The Anime, Ranked
When Historia, Ymir, Reiner, Bertholdt, and Connie were surrounded by a group of titans,the Survey Corpssaved them. Eren successfully stabbed one of the titans in the neck and was happy to get his first kill that way.
13He Learned To Accept Reality
Eren couldn’t believe it when Reiner and Bertholdtrevealed themselves to be the Armored and Colossal Titans. He didn’t want to think that someone he looked up to like a brother, as well as another close comrade, could be his enemies. However, once they transformed, Eren knew that he couldn’t deny it and fight back.
When Annie turned out to be the Female Titan, Eren hesitated to fight her even though the two weren’t close. Being able to fight against two of his close friends proved that Eren learned from his past mistake.
12He Activated The Coordinate
Atthe end of the second season, Eren found the titan that ate his mother. When he punched the titan, he activated the coordinate, causing her to be attacked by the other titans around them. At the time, Eren didn’t know what this ability was and everyone was surprised that he was able to do this.
It turned out that since Eren inherited the Founding Titan, he could control all the titans whenever he was made contact with someone from the Fritz family. The titan that ate Carla turned out to be Dina Fritz, a distant relative of Paradis' royal family.
11He Found Out How He Became A Titan
The method by which Eren obtained his powers remained a mystery for a long time. When he met Rod Reiss, the king of Paradis, he learned what happened. His father, Grisha, attacked the Fritz family in order to take Frieda Reiss' Founding Titan. He killed her and everyone around them, except for Rod.
Grisha then injected Eren with titan serum and had his son eat him, giving him both the Founding and Attack Titans that he inherited. Eren wasn’t able to remember this, and was shocked that he ate his own father without knowing it.
10He Learned About Grisha’s Past
When Eren remembered that his instructor, Keith, was friends with Grisha, he asked the former commander what he knew about his father. Keith had found Grisha outside the walls. Grisha told him that he couldn’t remember much about his past, so Keith brought him to Shiganshina, where he became the district’s doctor and met Carla.
Related:Attack On Titan: The Most Important Deaths In The Anime
However,Eren would learn later onthat Grisha’s amnesia was a lie. He pretended to forget everything because he was from Marley. With his first wife, Dina Fritz, he led the Eldian Restorationists. Once they were discovered, the group was turned into titans and sent to Paradis. A Marleyan officer that worked with them gave Grisha the Attack Titan and told him to start a new life within the walls.
9He Went Back Home
When the Survey Corps was ready to retake Wall Maria, Eren was finally able to go back to Shiganshina. It was the first time he, as well as Mikasa and Armin, had been there since they were children and saw the titans break into their home. Once they returned, they had to fight against the Colossal, Armored, and Beast Titans.
Luckily, Eren was able to fix the hole in the wall and was finally able to go into the basement of his childhood home, along withMikasa, Hange, and Levi. Here, Eren learned about Grisha’s life in Marley, along with other secrets about the world beyond the walls.
8He Defeated The Colossal Titan
Since the first episode, the Colossal Titan seemed to be the biggest threat in the series. Without Bertholdt kicking down the wall and letting the titans into Shiganshina, a lot of the events in the series wouldn’t have happened. During the Survey Corps fight against the Colossal, Beast, and Armored Titans, Eren and Armin teamed up to defeat Bertholdt.
They were able to trick him into letting his guard down and defeated him. However, as a result, Armin was almost burned to death. In order to save him, Levi injected Armin with titan serum and had him eat Bertholdt so he could inherit the Colossal Titan.
