Even Good Can Be a Weakness

Similar to how villains can be disgusted by the actions of other villains, some heroes can be good to the point that not only can it be used against them, but it can come off as appalling or pathetic by other heroes and/or villains (current or former). This usually refers to when a hero has a villain at their mercy or has a perfect chance to kill them and end the threat they pose, but out of the goodness of their heart, or some misguided respect, or even by being tricked by the villain themselves, let them go. As a consequence to heroes and their allies, following their good heart can, on rare occasions, trigger a series of events in which are either:


 * Their closest allies/friends ended up killed/heavily injured by their enemies that backstabbed them after being spared, in which either they ended up incapacitated or worse; dead before being resurrected later on or otherwise for the rest of the story, in which all cases are depended onto the story/fiction where it occured.
 * Suffer the huge loss on their side, ranging from having their supply destroyed or lost the very planet that they lived on.
 * Worst case, some of their allies ended up turned to the dark side out of fear, rage, or despair over the consequence of choice that hero made by spare their enemies (in some case overlaps with Despair Event Horizon as well), either the consequence was same with the previous case above or other causes that equally bad/worse.

Other examples of this could be either:


 * A hero openly expresses so much pride, or can be so naive in the good deed they've done that their allies or even witnesses can find it lame and obnoxious. Some cases of this also shown that the individual him/herself can potentially became the villain's pawn.
 * The hero overestimates/did not fully understanding unlikable traits of his allies/friends, in which when they reveal the said traits, it would became a serious trouble for the hero and his other allies.
 * The individual (either ther heroes themselves of others) overprotective with their relatives/subordinates/allies too much of something, which made their allies and even witnesses feels irritated. In some cases, their actions even too far to the point that he/she ended up ruin/hinders anything that their allies/friends dear most.
 * The hero attempt to do something with beneficial results for either themselves and their allies or everyone else, but they didn't fully took the necessary precaution for preventing the unwanted consequences.

While the heroes will do what it takes to correct the damage that is caused as a result of trusting their enemies, their mistakes often lead to irreversible consequences.

Since a person's sense of goodness differs from person to person, the members of audience often have differing opinions and both sides can get supporters.

Literature

 * Harry Potter:
 * In Prisoner of Azcaban, Harry Potter spares Wormtail by proxy, only to have him escape and help ensure Voldemort's return.
 * Rubeus Hagrid releases his pet giant spider Aragog into the Forbidden forest to prevent it from being killed and even finds it a mate. Unfortunately, Aragog, whom later grown into huge sized years later and having a thousand children, have little to no control his brethrens' hunger frenzy when Harry and Ron visited him for seeking for answer of mass-petrification that occured in Hogwarts, giving them troubles in the giant spiders chase. Then, Death Eaters easily recruit his brethren as Aragog no longer have any authority them due to his death due to natural age.
 * Albus Dumbledore has arranged for Doloris Umbridge to be released from Centaur captivity, only for her to persecute and sentence muggle-borns and half bloods to death during Voldemort's reign. This was fortunately undone by the time of Voldemort's death, where she was eventually confined in Azkaban for the rest of her life along with the rest of captured Death Eaters.
 * Things that may count as this was when Dumbledore enlisted the young Voldemort to enrolls in Hogwarts, only to the said future Dark Lord use the knowledge and secrets within the said school as well as founded what would be called Death Eaters against the whole world and mankind. However, Dumbledore managed to counteract most of the consequence of this mistakes from the beginning where he has ensured that Voldemort won't be allowed for working in Hogwarts by the time of his graduation and also researching every single bits of things that related with his backstory as seen in events in The Half-Blood Prince. Unfortunately however, Dumbledore never predicted that Voldemort managed to hid one of his Horcruxes in Hogwarts (Namely Ravenclaw's Diadem), though it was succesfully destroyed by Harry Potter.
 * Due to their past friendship, Annabeth couldn’t do her best to stop Luke and still believe that his betrayal simply out of being manipulated. Though in reality Luke himself also have his own reason of his betrayal(which made Annabeth’s belief was not accurate), Luke himself couldn’t bring himself to kill Annabeth as he still love her, and tries to persuade her to join him instead.

Live Action Films

 * Jedi Order has a code that makes them passive during wars, when they are needed, they don't execute Sith or other enemies, what later echoes on them.
 * Caesar trusts Koba as the advisor of Ape Colony as both of them believe that apes are better than humans and aware that Koba hate humans for their abuse and torture against him. However, Caesar is unaware how worse Koba's hatred against humans when he let humans to working on a dam that located near the Ape Colony; he had a tense agrument with Koba that angered with his kindness, even after Carver previously furiously tries to shoot Milo when Milo unintentionally found his hidden gun from his box supply. Unfortunately, Caesar's previous opinion about mankind and his kindness with them became catalyst for Koba to start the war against human race, which made him realize how blind he was with both fact where Koba's hatred against mankind was very immense and mankind and apes actually counterparting each other.
 * Tony Stark and Bruce Banner created Ultron as a peacekeeper program with help of one of the Infinity Stone within Loki's Sceptre, but unfortunately, the said program unable to cope with the negative traits of humanity and ended up chooses to rebel and decided to destroyed humanity. Worse, Ultron's first victim was J.A.R.V.I.S., which caused Thor and Steve Rogers berates Tony for this mess. Even though that this ultimately undone thanks to help of Vision (whom born from Ultron's latest new body which programmed with the remains of J.A.R.V.I.S.) and the redeemed Maximoff siblings, it was obvious that Steve eventually became distrustful on Tony since the accident, in which foreshadowing their future rivalries in Captain America: Civil War.
 * When Steve caught Tony tries to upload J.A.R.V.I.S. into Vision, he attacked them out of belief that he would repeat the same mistake, though Thor proved this wrong by help Tony and revealed that attempt to destroy Vision would be ended up far more disastrous than Ultron's own evil scheme due to the existence of Infinity Gem on Vision's forehead, in which Vision later help the Avengers to kill Ultron and stopped his evil plan.
 * This also not the first time Steve Rogers berate his ally whom tries to do good thing that ended up disastrous: He once diagree with Nick Fury's idea regarding Project Insight, which of course, backfires when some S.H.I.E.L.D members betrayed their allies and revealed themselves as HYDRA members and caused the project targets the innocent people alongside those whom potentially get in HYDRA's way.

Comics

 * Batman (comics): He has a principle of never killing, what gives most of his enemies a chance to escape prisons or asylums and start commiting crimes again. Anarky mentions in game Batman: Arkham Origins that Batman doesn't save Gotham people, but makes them dependant on him. In Arkham City he told Joker that no matter what evil he commited, he still wanted to save him, but he was to late. Tragically, in the comic series, it was also these principles that gave the Joker the chance to beat Jason Todd, who was Robin at the time, to death, who would later be resurrected and, feeling betrayed by Batman's morals, chose to become the second Red Hood.
 * Batman was once, thought about reasoning with his nemesis Joker about his evil deeds. Though this action had little to no damage unlike other examples that shown here, it was obvious that Batman realized that the evil clown, unlike his various enemies, are too insane for having redeeming qualities.

Cartoon and Animate Films

 * Marlin: Though Marlin tries to protect Nemo from diver's boat like every parent did to their child when Nemo and his friends dscovered one near the open sea, Marlin's foolishness and overprotective attitude over his son ultimately drove him insult Nemo, something that made Nemo ended up rebels out of the irritation and kidnapped by human divers.
 * Marlin also nearly repeat his mistakes again when he tries to pull Nemo for safety from the huge net that snares both Dory and unfortunate fishes until Nemo convince him that he know how to save Dory thanks to his experience along with other fish captives in Sherman's captive. Had Nemo's pleads to save Dory failed to snapped Marlin's foolishness during the said situation, Marlin would inevitably left Dory to die along with thousand fishes that snared by fishermen's ship.
 * The Queen of Ant Island: She believes that the only thing to keep her colony safe from Hopper and his army's wrath was by appease him, only to realized that Flick's solution for their troubles to rebel against them was the noble decision as Hopper only intended to turned the colony into slaves.
 * Against his father’s warnings, Hiccup was thought that he could reasoning with Drago for changing his mind from attacking Berk instead stoped him through violence means, which proved to be fatal mistake as Drago’s reason for turned to the dark side was revealed out of his twisted view of the world since the conflict with dragons. Worse, Drago responded to Hiccup’s said attempt by having his dragon brainwash every single adult dragon to turned against everyone in Berk, including Toothless, whom ended up became destructive slave of it’s former self that inevitably tried to blast Hiccup, but ended up hitting Stoick instead.
 * Avatar Series
 * Korra and his gang recruited Kai, a young boy with recently newfound airbending powers that turned out has kleptomaniac tendencies in spite of being a good guy. Though Bolin and Mako were tasked to ensure to keep Kai's kleptomaniac tendencies at bay, they not expecting him for easily outsmart them several times until the matter eventually settles down with the boy redeeming himself later on.
 * Roku: He didn't use any of chances to kill Sozin due to their old friendship, Sozin used it against him and left him to die, so he could no longer disturb his plans of world domination. Roku's spirit many times expressed his regret that he wasn't more decisive and didn't prevent a war that lasted a century.
 * Aang: He saved Zuko instead of leaving him to freeze to death, but later he turned against him in Ba Sing Se. He didn't finish his training to come back to Ba Sing Se to save Katara, but he was unprepared. Because he was educated that all life is sacred, he didn't want to kill Firelord Ozai, which nearly costed him his life and victory.
 * Zuko: He didn't want to young recruits to be sacrificed in battle, what was recognized as a disrespect to his father, who later challenged him to fight. Zuko refused to fight his father, what resulted him to burn a great scar on his son's face for the rest of his life, Zuko was humiliated and exiled. When he attempted to redeem himself, he almost lost his relationship with Mai. When he was already a Firelord, his patriotism and devotion to duty made him ultimately lose his beloved, severing his friendship with Avatar Aang, and risked a war he could not win (though he later undoes most of his mistake after realizing that most of his problems turned out due to his own fear of turning to the dark side as worse as Ozai ever did). Also, despite what Azula did to him, he didn't want to kill her, what resulted her escape.
 * Bubbles: Due to her love to animals, she tries to save them all, however she saved a cat that later was revelated to be a criminal mastermind, she was fooled by the cat's charm.
 * Optimus Prime: Referring to the Transformers: Prime series, during the war for Cybertron, according to his oldest friend, Ratchet, Optimus Prime had many chances to kill their worst enemy, Megatron, but let him go out of the respect he once held for the one he once considered a brother, as they both once worked together to rid Cybertron of corruption and inequality before the war started.
 * Gwen Tennyson successfully goes back in time and prevents Kevin's monstrous mutation ...only for her to find out that her meddling in time has caused a Bad Future were Hex rules the Earth, Kevin's Charmcaster's slave, Ben's chained in a dungeon as Hex's prisoner, and she's dead.
 * Scrooge McDuck becomes a vigilante to fight crime in "Masked Mallard", but a crooked TV reporter copies the identity to commit crimes and blame the hero in his REPORTS in order to boost ratings.
 * In Justice League: Doom, Batman prepered plans to stop Justice League members, if they turn villains, a team of villains decided to steal a bunch of data from his computer to use it against entire Justice League.
 * SpongeBob SquarePants: Though SpongeBob being a good guy, he can sometimes go crazy or easily manipulated by villains of SpongeBob franchise due to his jerkish nature (notably his idiocy, obnoxiousness, overly trusting, and very gullible personality). The worst instance was in A Pal for Gary, where he bought Puffy Fluffy as Gary's roommate (oblivious with the fact that the animal itself is one of the known apex predators in the ocean). And when the Fluffy reveals it's true apex predator form and nearly kills Gary, SpongeBob himself yells at Gary for attacking him (unaware that the situation was polar opposite of what he thinks) and was nearly killed had Gary not defeated it. Then SpongeBob later proves too ungrateful for Gary by robbed him his free time in his house, much to fans’ irritation and The Mysterious Mr. Enter's wrath.

Anime and Manga

 * Dragon Ball Villains
 * Goku: When his evil brother, Raditz came to Earth, kidnapped his son, Gohan, and threatened to kill every life form on the planet, Goku had to team up with his former enemy, Piccolo, to have the best chance of defeating him. Goku, not wanting to tip Raditz off about his knowledge of his tail being his weakness, waited until the right moment to grab Raditz' tail, rendering him immobile and defenseless against Piccolo's lethal Special Beam Cannon technique. Raditz begged Goku to spare him and promised to leave Earth and never returned. Initially, Goku refused to believe him, but soon gave in once Raditz sounded sincere enough to keep his word, despite Piccolo warning him twice not to fall for it. Raditz immediately beat Goku down the moment he let him go. Piccolo angrily chasticed Goku for his naive nature.
 * Gohan: In the anime-exclusive episodes of Dragonball Z, Gohan assumed an alter-ego by the name of "Great Saiyaman" to keep his identity a secret from the public whenever he fought crime. When he saved an airline jet from crashing in a highly populated city, he declared his success with an obnoxious speech and striking several over-the-top victory poses. A little girl who watched denounced him as a "geek". Something like this happened again in the 13th movie, when he stopped two bank robbers from escaping in their getaway car. Once he disarmed them and disabled their vehicle, he made another long-winded speech and struck another pose. One of the bank-robbers questioned the length of the speech and even Videl, Gohan's girlfriend, who had also assumed a similar alter-ego and aided him in foiling the robbery, agreed, even telling him "See, Gohan? Even the low-lives agree.".
 * Naruto
 * Naruto Uzumaki: because of his bond with Sasuke Uchiha (only he cared about from those two) he didn't do his best to stop Sasuke from defecting; he refused to kill Sasuke, when he had perfect opportunity, in which allowed Sasuke to become an international criminal and preserve his alliance with Akatsuki thanks to Sasuke's own vulnerability to Obito's manipulations. Despite this, Naruto himself still giving Sasuke chance to return for the good side by his own way, albeit in far more serious way than before after seeing how severe the damage that he caused after turned to the dark side further.
 * It was reasonable that Naruto was critized by his friends and also by A The Raikage, whom yelled at him because Sasuke seemingly killed Killer Bee that left him in vengeful rage until Tobi revealed that the said person escaped, but use this as ruse for have fun on the outside of the village.
 * Sai, whom aware with this matter convince Naruto's friends that Sasuke can only be stopped by Konoha alone and nothing else, as had other village did so instead like A (which fortunately not happened), some of Konoha shinobi would sought revenge and there's a chance that the said individuals accidently killed wrong person from other village, resulting all villages wage war against each other and would only driven by hatred. Unfortunately, this backfires as Sakura turned against them so she could taking out Sasuke by himself, which turned out a suicide attempt had Naruto not interfere. Even with Sai himself tries to undo the unwanted consequences of this, it's turned out that Naruto was undo this instead.
 * Itachi Uchiha: ordered to kill his entire clan to prevent a bloody coup that would kill all of Konoha, couldn't bring himself to kill his younger brother, Sasuke. As a result, he spared said person, and tried to enact a plan that would end with that person a hero beloved by Konoha, and capable of defending himself and it against the Madara. Instead, it ended with him as Obito to Madara, swearing to destroy Konoha. He later fix this out though once revived by Kabuto later on.
 * Out of concern with another possible rebellion from Uchiha clan, Tobirama Senju gave the Uchiha control of the Konoha Military Police Force as a sign of trust as well as means to keeping the Uchiha's emotions in check so the village would not end up with another Madara. Though this actually meant for Uchiha clan and inhabitants of Konoha to coexist in better way, this ultimately intensifies the chance for Uchiha clan to consumed by hatred.
 * Ichigo Kurosaki and his friends went to Hueco Mundo to save Orihime defying Soul Society's orders. Yamamoto, who had hoped to be able to send a captain-class invasion force in three months time was forced to speed up his plans to get the captains into Hueco Mundo to follow after the kids. Then it's revealed this was Aizen's plan all along, knowing Orihime's unique powers would force the shinigami to act to prevent her power being used by Aizen. Aizen successfully split the Gotei 13 forces in half, enabling him to have to only fight half the Gotei 13 at Karakura Town.
 * Orihime Inoue: she healed Menoly despite she abused her, then she returned to abuse her more sadistically.

Live Action T
Merrick Baliton used the cursed wolf mask to summon Predazord to defeat the first Master Org, only to possessed by Zen-Aku, the evil Org whom used this opportunity to possessed him and turned him into the said Org and later, is forced to be sealed within a coffin for thousand years. Though the 20th century generation of Power Rangers Wild Force learned about this and exorcizing Merrick from Zen-Aku's influence, their action not entirely beneficial for Merrick: By exorcizing the silver Ranger, they also caused the destruction of the wolf mask that sealed Zen-Aku's Org Essence, which allowed the said Org to finally free so he could after Merrick and rejoin him. Merrick's problem with Zen-Aku whom returned to after him was not entirely his and the Rangers' fault, as at that time, they mistaken Zen-Aku as Merrick's evil self, not the true Org and therefore, how Merrick became Zen-Aku was obviously possession.
 * Kilgharrah the Great Dragon|Kilgharrah]] told Merlin that his attempt to see other people’s kindness can be his undoing. This was proved where Morgana and Mordred, those whom he attempt to see their kindness proved to be vulnearable to turned to the dark side. Though Merlin tries to undo this once heard about propechy where Morgana and Mordred would became evil, both of them already one step past to the dark side: Mordred callously killed two Camelot Knights instead simply immobilize them by his sonic scream spell, while Morgana start her move by mentally tortured Uther with a magically specialized mandrake Root.

Video Games

 * In Star Wars 'The Force Unleashed, Rahm Kota implores Galen Marek not to kill Emperor Palpatine despite Marek wanting to do so anyway. Marek eventually listens to Kota when the Jedi Master tells Marek that if he DOES strike down Palpatine, he'll likely become evil again. This allows Palpatine to attack Marek and the rebel leaders again. Marek shields Kota and the rebel leaders at the cost of his own life. Ultimatly Marek's sacrifice allowed the birth of the Rebel Alliance, on the negative side his refusal to kill Palpatine began the long Galactic Civil War. Even though the war ended with the fall of the Galactic Empire and Palpatine's death, it still resulted in the death's of billions, including the destruction of Alderaan.
 * Commander Shepard can choose to spare Rana Thanoptis and Elnora, but later the former becomes a brainwashed agent of Reapers and the latter is revelated to be a murderer of a volus businessman. Shepard can also choose to destroy the Collector Base over preserving it, what gives less military power in the next game.
 * Geralt of Rivia can believe those, who look like obvious victims, but looks are deceiving. An elven girl Malena is an ungrateful backstabber and three sisters are wraiths, who were lying from the start and manipulated the witcher.
 * Mega Man and several of his other counterparts are known for having naivete, which their enemies would often point out may be their fatal flaws. For example, when he and Bass meet in battle, Mega Man would often state his refusal to fight him out of belief that they are not enemies. Another example is found in Mega Man X, who shows a lot of qualms about having to fight due to being a pacifist at heart.
 * Spiritia Rosenberg has her own naivete similarly to Mega Man above. Interestingly, her naiveness mainly comes from trusting Iris Sepperin, who eventually reveals herself to be the one responsible for having been orchestrating RKS's rebellion against the Orthodox Church all along.
 * Sash Lilac and Carol Tea are forced to turn the system for Lord Brevon's spaceship back on and give him the disk they were using to do so by him when he threatens to kill Milla Basset following their attempt to shut it down. Little do they know, that Brevon has tricked them into doing so so that he could mutate Milla into a monster and force the two to fight her.
 * Protagonist of the first Fallout game was forced to sent himself into exile from the Vault because his/her heroic action in saving the Vault from army of mutants has inspired the children inhabitants to do heroic actions that similar with what he did, an influence that threaten to bring the unwanted consequences.