Isayama created Eren with the idea of a character whose fears and dreams were relatable but often clashed with his own darkness, resulting into multiple changes to his characterization.

[2] Isayama has stated that part of the reason he chose the name "Eren" for the character is because it sounds feminine, which would make it easier to remember.

[3] Isayama has stated that he has struggled in the past to make Eren feel "alive" when writing and has called the character "a slave to the story".

Because Eren is an energetic character, Isayama chose to give him black hair so that it would be easier to draw speed lines around him when he is moving.

[6] Japanese actor Yūki Kaji commented on how it was important that he should voice Eren's Titan form because he believes it is an extension of the character.

[16] He was excited because Eren was different from his previous characters despite sharing a similar age and vocal range, he commented "It's a very raw sound.

[18] Isayama describes Eren's personality as that of a child who uses rage as his motivation as a result of his weakness and failure to save his mother from the Titans.

[20] In later chapters when confronting Annie, Isayama wanted to give Eren more responsibility by making him suffer the powerlessness of his allies being killed by the traitor.

[19] Talking more about Eren's rivalries, Isayama instead compared him with Luke Skywalker from Star Wars as he finds fitting how both characters have an inner conflict with their darker personas.

However, Isayama stated that starting this moment, Eren and his friends began to mature and fill positions left behind by military superiors.

Isayama said that viewing Eren as "dragged along by the story" had become the essence of his character, and that Mikasa and Armin had developed a habitual mindset of revolving around him and wishing to help him.

According to Isayama, at first their mindset was favoritism, comparing Eren's relationships with Mikasa and Armin to that of helping one's relatives or siblings who are encountering hardship, even if onlookers question it.

While Armin possessed a global-oriented curiosity and dreamed of the natural world outside the walls, Eren instead held only self-focused indignation towards the lack of freedom that mankind had to seeing it, causing an inner part of him to wonder if he was empty-headed.

[22] Eren Yeager is introduced as a ten-year-old residing in the town of Shiganshina who dreams of joining the Survey Corps in order to explore the outside world beyond the walls.

A year prior to the events of the story, accompanying his father Grisha to meet her parents, Eren saves Mikasa Ackerman from a group of kidnappers, which led to the development of his ideology at a young age.

Four years later, assumed to have been fending off Marleyan infiltrators with the new Colossal Titan Armin, Eren is leading the Survey Corps in an extraction of Zeke in Liberio following Marley having won its war with the Mid-East Allied Forces.

[33] Eren's actions result in his arrest but he escapes with a group of Survey Corps members loyal to him called "Yeagerists", and he resumes his search for Zeke.

Revived, Eren frees the Titans within the Walls and declares his intent to exterminate all life outside Paradis in order to protect his people, becoming the world's enemy.

Armin wakes up with a memory of Eren telling him in the Paths his true plan to make his friends heroes by killing him.

With Eren dead and 80% of the world's population exterminated, the Founder's power is lost and the Titan Shifters rejoice as they are permanently transformed back into humans.

By incorporating the unusual traits of Hallucigenia, Isayama designed a disturbing silhouette that seems to defy anatomical logic, amplifying the monstrous and inhuman aspects of this Titan.

This inspiration highlights Isayama’s ability to merge real and fictional elements to enrich the aesthetic of his work, thus adding a striking visual and symbolic depth to his universe.

[37] In the visual novel Attack on Titan: Lost Girls an alternative take of the character shows his relationship with Mikasa, who fears that, regardless of changes in history, Eren is fated to die.

In "Akuma no Ko", Eren's motives and characterization are depicted throughout, a mirror of the series' first ending song "Utsukushiki Zankoku na Sekai".

Jacob Hope Chapman of Anime News Network referred to Eren as "almost deliberately not a 'likable' protagonist, even by 15-year-old boy standards" due to reasons of being violent, impulsive, and not especially smart or strong.

[72][73] Kyle Charizanis of The Fandom Post found the anime portrayal of Eren's transformation to be amusing, starting from his "almost pitiful" look while declaring how he's going to kill all of the Titans.

Nicole MacLean of THEM Anime Reviews found him "a frustrating protagonist" based on how his angry fits and exclamations “can be seen as highly childish”.

[83] MangaTokyo acclaimed Eren's growth across the anime series' until the finale of its third season due to how he realizes the amount of enemies he has to face changing from having angry tantrums to a more collected mind seeking the freedom of his people.

[86] Another reviewer praised how the development of the characters and discovery of the truth behind Grisha also reflected on the childhood moments from Eren, Mikasa and Armin.

[87] For the final arc, Den of Geek and IGN noted that while Eren becomes a darker character due to his harsh interactions to Mikasa and Armin to the point he comes across as a fallen villain with Zeke being the apparent cause.