In anime, there is a general expectation that doing the right or "moral" thing will often pay favorable dividends. For example, a hero's choice to show mercy against an evildoer will later see that same villain joining their side (whether temporarily or otherwise).

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However, there have been many instances where a character gravely regretted their actions regardless of how righteous the deed might have been. Through identifying them, we gain a better look into their psyches and understand what part of their charity went awry. Moreover, it becomes easier to comprehend the reason behind their chagrin.

10 Midoriya Was Right To Keep All Might's Secret But Later Told Bakugo Anyway (My Hero Academia)

Bakugo Bullying Midoriya

After being humiliated in their first training exercise against each other at U.A, Bakugo was livid. He thought that Midoriya was deliberately attempting to hide his quirk and had been messing with him for their entire childhood.

At first, Midoriya was responsibly inclined to keep All Might's secret as he had promised. However, it wasn't long before he cracked and told Bakugo that he was One For All's successor. Ironically, his rival didn't believe him when he first heard the truth.

9 Eren Regretted Turning Around To Fight Annie In The Forest (Attack On Titan)

annie vs eren aot

After Levi's squad had been all but wiped out, Eren's conscience weighed heavily on him. When the Female Titan manifested a second time, he refused to run and instead fought against her directly.

He would almost instantly regret this decision. Annie's superior combat skills in conjunction with her hardening abilities made the fight extremely swift and one-sided. Eren would later be reprimanded for his recklessness, especially since he got Levi's leg broken in order to save him.

8 Meliodas Regretted Killing Fraudrin (Seven Deadly Sins)

Meliodas 1 shots fraudrin

After being killed by Estarossa, Meliodas became more attuned with his demonic nature. During the battle for Liones against the Ten Commandments, he came across Fraudrin a second time - the same villain who'd been responsible for much of his heartache and suffering.

Even after he surrendered, the captain disintegrated him in a single punch. His comrades were horrified at this ruthless behavior, and even Ban posited that it was unlike the captain's usually hospitable nature. Meliodas would later express his own regret even though letting Fraudrin live would've been extremely risky to the heroes' endeavors.

7 Ace's Attempt To Stop Blackbeard Put Luffy In Even More Danger (One Piece)

ace in one piece

After an arduous search, Ace finally came upon Blackbeard. The traitor told his former companion that he was interested in capturing Monkey D. Luffy so that he could become an honorary Warlord.

Enraged at Blackbeard's intentions, Ace attacked him in an attempt to keep his brother safe. After being subdued, he would ironically place Luffy in even more danger, as his brother was forced to brave the rigors of both Impel Down and Marineford in order to save him.

6 L Gave Light The Presumption Of Innocence Even Though He Knew He Was Kira (Death Note)

Death Note Light And L Split Screen Saying "I Am Justice"

Ever since inviting him to the task force, L had a strong premonition that Light was the Kira killer they had been searching for. Over the months they spent together, he confirmed his hunch to be true.

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In spite of this, he never actually took any drastic or unscrupulous measures to put Light down for good. This was for two reasons; not only did he consider his rival as a friend, he understood that his current evidence was insufficient. In his final moments, L was validated about everything he had come to believe but failed to take action on.

5 Kirito Honored Heathcliff's Terms & Paid The Price For It Later (Sword Art Online)

Kirito versus Heathcliff in Sword Art Online.

Kirito fought Heathcliff for the right to take Asuma from his guild. Since he failed in their duel, he was under obligation to join his opponent's organization and did so willingly even though he suspected foul play.

Despite his upright comportment, Kirito would soon regret having ever agreed to serve him. It was later revealed that the guild master was actually the original architect behind Aincrad and the man who subjugated hundreds of thousands of players to his twisted game.

4 Sasuke Spared Naruto At The Valley Of The End (Naruto)

Naruto fights Sasuke

Although Naruto and Sasuke were evenly matched in the fight at the Valley of the End, the latter was ultimately able to gain the upper hand and defeat his rival regardless of Kurama's influence. He understood that killing him would cause the emotional turmoil necessary to evolve his sharigan.

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However, the rogue ninja refused to do so and instead walked away. Sasuke would later repeatedly state that he regretted his mercy, especially in subsequent encounters with Naruto himself.

3 Silva Zoldyck Was Disappointed About Killua's Actions After He Gave Him Freedom (Hunter X Hunter)

Hunter X Hunter's Silva Zoldyck and Killua Zoldyck Having A Conversation

After repeated displays of defiance, Killua faced his father directly and told him that he wasn't interested in the family vocation. Much to his surprise, Silva was understanding and allowed his son to choose his own path. He suspected that with a little time, Killua would come around and see his perspective.

However, he was almost immediately proven wrong. The young boy promptly stole Alluka from the family's possession, who had served as one of its greatest assets up until that point.

2 George Joestar Took Dio In As An Orphan But Was Ultimately Murdered By Him (JoJo's Bizarre Adventure)

Jonathan Joestar, Death of George from Jojo's Bizzare Adventure

After being saved by Dario, George vowed to repay the Brando family in any way he could. Once he became an orphan, Dio was escorted to the Joestar manor and meant to be raised there as a son.

In spite of the kindness George showed his mansion's newest guest, the boy would ultimately prove to be his undoing. Not only did he torment Jonathan throughout his childhood, he actively poisoned his adoptive parent when he was already gravely ill.

1 All For One Regretted Giving His Brother More Quirks (My Hero Academia)

All For One gives his brother a quirk

During his rise to prominence, All For One pitied his "quirkless" brother and thought that if he gave him power, he would be more sympathetic to his goals. As a result, he granted him one of his many abilities - a mistake that would inevitably be his undoing.

In actuality, All For One's brother had his own power called "One For All." It stockpiled and enhanced quirks as it was passed down between users. Over the years, it became increasingly difficult for the villain to defeat his sibling's successors before his downfall at Kamino.

NEXT: My Hero Academia: 10 Ways All For One Is The Most Terrifying Anime Villain Alive