Attack On Titan's characters live their lives in constant danger, forced to make split-second, life-altering decisions in the heat of the moment, often bringing about someone's grisly demise. When mistakes have such an impact upon one's life and the lives of others, and one is faced with these impossible scenarios nearly every day of their life, it's inevitable that someday a mistake will be made.

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When the words spoken or actions taken at any moment could be the difference between life and death, the impact of a single, seemingly minuscule mistake could be devastating. So, when one inevitably makes a mistake, that one mistake can haunt them forever.

10 Erwin Smith: Never Fulfilling His Dream

Anime Attack On Titan Perfect Game Erwin Advances

As 13th Commander of the Survey Corps, Erwin devoted his life to discovering the origin of the Titans, leading droves of soldiers to their deaths to fulfill this ambition. Eventually, Erwin's mistake leads them into Zeke's trap, and he's forced to "give up on his dreams and die," for the sake of his goal. With his sacrifice, the Yeager basement was uncovered, and the answers unveiled.

Despite his efforts, it was his mistake, a single decision that prevented him from being present at the moment he devoted his life to and was therefore never privy to the knowledge he sought.  This inability to fulfill one's lifelong dream over a simple mistake would haunt someone, even in death.

9 Ymir: Not Marrying Historia

Ymri and Reiner while Ymir writes a note

From the beginning, Ymir devoted her life to Historia, enlisting solely to find the illegitimate royal. Despite a rocky start to their relationship, they grew close quickly. In Historia, Ymir found her purpose, and she did everything in her power to stay with her.  However, Ymir made the mistake of giving in to Reiner and Bertolt and returning with them to Marley, unwilling to face the potential persecution within the Walls.

After leaving, Ymir sent a letter for Historia, confessing her love and that her only regret was not being able to marry her. Ymir made the mistake of leaving Historia, and she came to regret her decision, tormented by her lost love until her end.

8 Gabi Braun: Her Hatred

Gabi realizes that there are no devils on Paradis Island - Attack on Titan

Raised in Marley, Gabi was taught to hate her Eldian heritage, force-fed propaganda that claimed she could only be "redeemed" by eliminating the "Island Devils" from Paradis. An impressionable child, she latched onto the idea, looking for someone to blame for her suffering. This hateful mindset led her to make horrible mistakes, committing crimes for a country that despised her and justifying her actions with the idea that people in Paradis were nothing more than devils.

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However, after Gabi is forced to spend time on Paradis, she realizes how wrong she'd been about the people of the island, that they're simply human. This realization allows her to grasp the magnitude of her mistakes, of the words and actions that she can't take back, and she comes to see that the true devils reside within herself.

7 Falco Grice: Drinking Zeke's Wine

Attack on Titan Falco

Falco was raised with Gabi as a Warrior and followed her to Paradis to keep her safe. Unfortunately, Falco was caught in Zeke's plan, mistakenly ingesting his spinal fluid when drinking wine intended for the military on Paradis. In an effort to save him, he's taken to Zeke by Colt and Gabi, who refused to stop his plan to save Falco's life.

Zeke screams, and Falco is transformed into a Pure Titan, killing his brother Colt, then attacks Reiner, and eventually eats Porco, inheriting the Jaw Titan. When he learns what his mistake caused, he is filled with grief, haunted by the blood of his brother and mentor that is on his hands.

6 Zeke Yeager: Trusting Eren

Zeke Discovers Eren's Betrayal - Attack on Titan Anime

When Zeke was first introduced, he appeared as devastating power in the form of the Beast Titan. He planned to "save" the Eldian race with his euthanization plan, manipulating Eren into using The Founder to achieve his goals, spurred on by hatred for a father that abandoned him.

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Unfortunately for Zeke, his mistake was assuming that Eren was a brainwashed child that needed saving, instead of the puppeteer manipulating the situation all along, controlling their father and the future. In believing that Eren had been raised as he'd been, he mistakenly placed his trust in Eren and lost his only chance of succeeding. When Zeke finally came to realize the truth, he was horrified, but it was too late, and it's clear that this mistake will haunt him forever.

5 Connie Springer: Taking Falco

Connie Springer Attack on Titan Season 4

Connie comes from a small village called Ragako, one of the first to be changed into Titans by Zeke. For years, Connie was forced to visit his transformed mother, trapped on the roof of his decimated home. When Falco falls unconscious after inheriting the Jaw Titan, he seizes what he believes is an opportunity to save his mother, taking Falco with the intention of feeding him to her.

However, when the time comes, he's forced to come to terms with the reality of the situation, and how much of a mistake it was.  He's horrified with his actions, attempting to murder an innocent child, and vows to spend the rest of his days saving lives to help him cope with his egregious mistake.

4 Levi Ackerman: His Absence

Levi Slaughters The Beast Titan in Attack on Titan

Levi is one of the most powerful characters, with nearly unmatched skill in battle. Despite his overwhelming power, it never seems to be enough, as he continues to lose everyone that he dares to care for. The pain of each loss is combined with guilt and regret, stemming from his absence in their final moments when they needed him most.

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He mistakenly chose to chase Erwin, leaving Furlan and Isabel behind, and returned to find their bodies. He left his squad in the forest and returned to find them struck down by the Female Titan. He always seems to make a mistake in choosing where to be, leaving anger and regret in knowing that if he had been there, he could have possibly saved them.

3 Armin Arlert: Being Saved Instead Of Erwin

Armin in Attack on Titan

When Levi chose to save Armin instead of Erwin, he thrust a role upon a child that he shouldn't have been tasked with, placing an unbearable burden on his shoulders, the need to prove that he was the right choice. It's clear that Armin believes it was a mistake to save him and is tormented by the fact that his revival came at the cost of Erwin's life.

While it's clear that Armin was the right choice, Armin will be haunted by that decision forever, forced to wonder whether his existence is a mistake, if the outcome would have been different had he not been the one revived.

2 Mikasa Ackerman: Eren's Death

Mikasa Ackermann is still heartbroken by Eren's betrayal in Attack on Titan

It's clear from the beginning of the story that Mikasa is devoted to Eren, protecting and caring for him even when he objected.  Her devotion drives her to stay by him, even as he heads down a path that she is reluctant to follow.

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So, despite the fact that it was her wielding the blade that sealed Eren's fate, she will be haunted by his death as long as she lives.  Left wondering about what could have been, the life they could have had together, and if there was some mistake she made in that final conversation, that if prevented, would have allowed him to be saved.

1 Eren Yeager: The Means To Save Paradis

Eren Yeager about to meet the original Ymir from Attack on Titan

Eren is perhaps the most complicated character in the series, his actions and motivations often being difficult to comprehend.  He's passionate and cares deeply, willing to do anything for those he cares about, including initiating The Rumbling, even if he's regretful of the extreme actions required to secure their freedom.

While it's debatable whether The Rumbling was a mistake or not, Eren certainly acknowledged how wrong his actions were and regretted the means he had to go about achieving his goals. His insistence upon his death is a clear expression of regret, his way of atoning for his mistakes, knowing that the world could never forgive him.

NEXT: Attack On Titan: 10 Times Nothing Went According To Plan