The Farmer and the Viper

"One winter a Farmer found a Viper frozen and numb with cold, and out of pity picked it up and placed it in his bosom. The Viper was no sooner revived by the warmth than it turned upon its benefactor and inflicted a fatal bite upon him; and as the poor man lay dying, he cried, "I have only got what I deserved, for taking compassion on so villainous a creature."

Kindness is thrown away upon the evil."

- Aesop's Fables, "The Farmer and the Viper"

What's this? An orphan has appeared near the Haunted Castle, or an addled drifter in need of help wanders into town, or perhaps an outright villain is shown Forgiveness and compassion once they've lost, and they are taken into a Good Samaritan's home and shown kindness. But in the middle of the night, their benefactor awakens to find the good silver stolen, the dog dead, and the house on fire -- all courtesy of the injured man they thought they could help.

They should have known better.

This Family-Unfriendly Aesop is much like Curiosity Is a Crapshoot: a display of friendship, trust, and love won't always bring about a redemption; sometimes evil will bite the hand extended to it.

Compare Morality Chain, where the Samaritan does somehow manage to restrain their ward's wickedness. Turn the Other Cheek is probably the Samaritan's mindset. The receiver may turn out to be a Bitch in Sheep's Clothing or a Jerk With a Heart of Jerk. When combined with Save the Villain, this is sometimes used to set up a Disney Villain Death. Compare Bad Samaritan, when it is the care-giver, not the care-receiver, who is evil.

Inverse of Good Samaritan and Androcles' Lion. See also Save the Villain, Taking You With Me, Take My Hand, Prisoner's Dilemma. See also They Were Holding You Back for a common justification for how the viper is really "helping."

Also called the Scorpion Dilemma, or The Frog and the Scorpion after a similar fable. (see Mythology, below) Not to be confused with "The Farmer and the Cowman."

Anime and Manga

 * In a later episode of Aria the NATURAL, Akari spots a woman who is dressed like she's just gotten back from a funeral. She is then told a ghost story about a woman in black who asks for transport, then spirits her gondolier away. That night, the woman in black asks Akari for a ride to a graveyard. Akari takes her (This is notably not the only example of Too Dumb to Live, because the anime consistently encourages naivety). Akari goes on her way, but the woman, in a weird subversion, grabs her hand and tries to spirit her away, specifically because she was impressed with Akari's kindness. The anime implies this to be a bad thing, but never makes it really clear.
 * In Dragonball Z, the last 5 minutes, and I do mean the actual 5 minutes, not the 5 minutes it takes for the planet to blow up, of Goku Vs. Frieza. After Frieza cuts himself in half with his own attack, Goku donates a small portion of his energy to him. As Frieza can breathe in space, he ought to be able to get off the exploding planet with the energy. Due to Frieza being too arrogant to live, he uses it to attack Goku instead. Having used up his already unreasonably merciful last chance, Goku blows him to bits. He somehow gets better eventually.
 * Only to be sliced in half AGAIN later on.
 * In Kino's Journey, Kino saves some stranded traders. It then turns out they trade human slaves and are looking to recuperate their losses.
 * Anyone who ever does anything remotely decent or nice for Monster's Johan Liebert ends up as the farmer.
 * In Vinland Saga, an English farmer and her daughter take pity on a young boy who stumble into their cottage, feeding and delousing him and sheltering him from the soldiers who are looking for a Viking spy and are killing all strangers on sight. In return, the boy burns down the village's dock, signaling the Vikings nearby to come take the village, which they do. Said boy is the protagonist.
 * In Fullmetal Alchemist, the disgraced and homeless Yoki is taken in by a group of Ishbalan refugees. He promptly betrays them by selling out the Serial Killer and fellow Ishbalan Scar to a bunch of bounty-hunters with the intent to split the bounty. The refugees don't take the idea of Yoki ratting out one of their own well and promptly give him a beat-down.
 * Also Scar himself, after he ...depending on the source material. In the first anime, it was Mustang being forced to do his job.
 * In the later chapters,, one of Edward's allies that Ed previously spared in battle, sneaks off and contacts to rat them out. It's all a
 * Subverted in Gundam 00. After defeating Ali Al-Saachez, destroying his Gundam Arche and cornering him in a hallway, Lockon Stratos gives the man who murdered his entire family one last chance at redemption. True to form, Ali whips out a gun while Lockon's back is turned...
 * In One Piece, Kaya's family takes in an apparently down-and-out man and makes him their butler. He is secretly the pirate Captain Kuro, with a long-term plan kill them, to steal their fortune, and retire on it.
 * Done likely by accident with Aokiji and Robin: Aokiji lets her live in spite of his order from the World Government, but, in spite of his warning to keep out of trouble, she's currently part of a crew who's leader declared war on the World Government.
 * In Okane ga Nai, Ayase saves Kanou, only to end up 4 years later as Kanou's love slave.
 * Rurouni Kenshin: The starving, lonesome little kid Enishi almost dies in the streets of a foreign country (China) until a rich Japanese family saves him, even going as far letting him stay for however long he needs, no questions asked about his obviously painful circumstances. He slaughters them and takes all their money.
 * But being cruel and evil is only half the reason: by his own accord, he killed them (as opposed to just stealing and running) because, having just lost his only beloved sister, it was "too painful to see a happy family".
 * A comic serial on the Tales of King Arthur had the Frog and Scorpion tale being told during an Enemy Mine situation...up to the point where the frog swims across the river with the scorpion on its back. Later on, he privately reveals the Downer Ending to his friend and jokes dryly that the story is a lot better without it.
 * Shinzo has this happening quite a lot; when Yakumo shows kindness towards a villain, you can bet they'll try to kill her anyway.
 * In Tsukigasa, a group of robbers save Kuroe's life and have him stay on as their doctor. Five years later he ends up stealing their special maps, running off, giving them to his former friend who is a Samurai so they can be tracked down, and personally killing the two that hunt him down. All because they were going to rob his Love Interest.
 * Not quite a straight example: in Code Geass, Lelouch uses his Geass to steal a Knightmare Frame from a Britannian soldier named Villeta Nu. He leaves her alive, the Geass clouding her memory but still leaving vague echos that lead to Villeta
 * Gundam Seed Destiny: poor, poor Shinn. The only way to save was to send her back to Neo, the only one who has the medical equipment to save her. He promised to keep her far from battlefields. What happens next?
 * Yzak and Deerka are a curious example. Chairman Durandal saved them during their trial for war crimes. But in the last episodes, they side with Lacus. So, here we have a Villain With Good Publicity saving some anti-heroes, and they bite him back by siding with the true good guys.

Comic Books
"Isis: How could you do this? We treated you like family. We loved you.
 * Occurs in a horrifying manner in the 52 miniseries set in the year after Infinite Crisis. Osiris, the brother-in-law of Black Adam, the (sort of) Evil Counterpart of Captain Marvel, takes in a lonely anthropomorphic crocodile as a pet/family member whom he names Sobek. For most of the series, Sobek is depicted as a cowardly yet friendly fellow with a huge appetite. . Sobek is a Big Eater because . When confronted with this by Isis, Osiris' sister and wife of Black Adam, what is the traitor's response?

My blood is cold!"


 * In a recent Batman Detective comics storyline, the Joker gets hit by a truck after trying to kill Robin. He gets taken in by a magician who came to Gotham to study its "fascinating" criminal element. The Joker repays his kindness by teaching him some tricks of the trade. Then the Joker garrotes him and . The Joker even refers to the "Farmer and the Viper" story while recapping his scheme to Batman.
 * Hell, Batman and Joker's entire relationship is this trope. Batman's refusal to kill Joker because If You Kill Him You Will Be Just Like Him is repaid by Joker's literally thousands of victims.
 * This is the Super-Hero Origin of Freddy Freeman aka Captain Marvel Junior, before he became Captain Marvel after Infinite Crisis. Freddy and his grandfather were fishing in a lake when Captain Nazi is thrown into it by Captain Marvel in the middle of their battle. Freddy and his grandfather help rescue Captain Nazi, who repays them by killing the grandfather and crippling Freddy. Captain Marvel shares the power of Shazam with Freddy to save him, turning him into Captain Marvel Junior.
 * A variation on the tale itself comes in the Academy Comics' Robotech II: The Sentinels Halloween special, where after going with an Away team against the wishes of his wife Lisa, Rick Hunter explains his actions with the story, basically telling her that he's always gonna be a little headstrong and willing to take risks. To which Lisa says: "So the moral of the story is you're a lying snake, huh?"
 * Played back in forth in a comic for Transformers Animated where Ratchet is shown helping a Decepticon suffering from "Cosmic Rust", a disease some Decepticons released in the middle of a battle. Ratchet does it on the grounds that while the commanders knew the score for doing such a thing, it's no reason to abandon a soldier..
 * Usagi Yojimbo also makes use of the "Farmer and the Viper" story when a hapless fisherman rescues Jei-san and fails to notice Jei's Milky White Eyes, ominous voice, and the mysterious chill that follows him. Jei even tells the story to the fisherman
 * The idea of The Power of Love failing to redeem is featured in Johnny the Homicidal Maniac, when Devi asks Johnny on a date. All seems to be going well at first, until Johnny realises that he's found someone who actually makes him feel happy. He then in order to "immortalise the moment." This goes to show how completely fucked up his mind is, as well as kill the idea of any more romance in the series.
 * In The Sandman, Loki's urge to punish Morpheus because Morpheus helped him escape his eternal torment. Odin even cites this Aesop when pointing out to Morpheus how it is in Loki's nature to repay kindness with malice and ingratitude.
 * The Question recites a version of this parable to himself after he is attacked by a biker who he just saved from a fire.
 * Deadshot references the frog and scorpion version in Secret Six after apparently betraying the team.

Fan Fiction

 * In Light and Dark The Adventures of Dark Yagami, after a nuclear bomb goes off, Kyosuke Higuchi "Yotsuba" is killed in a nuclear bomb blast and asks Dark to save him with his Life Note. Dark does and Yotsuba immediately tries to kill him for his master L.
 * In A Cure for Love, after having  killed Light feels a bit uncomfortable later when he remembers how   saved his life.
 * Point of Succession: Unlike all the other doctors Light refused to be intimidated by B and would not give up on him and so B comes to transfer his obsession to Light...

Film

 * The aesop's actually told by a Native American who shelters the serial-killing couple in Natural Born Killers.
 * It was also told in The Crying Game; first by Jody towards the beginning of the movie, then Fergus tells it to  at the end of the film.
 * It's a subversion of sorts, in that it states that good people will do the right or at least honorable thing because it's in their nature to do so.
 * In the film Flesh and Bone, a starved and abused boy is discovered by a kind family. They take him into their home for the night to care for. When they go to sleep, the boy lets in his father (James Caan), who then proceeds to kill the whole family before robbing the house. This is a ploy the father and son had repeated many time before and since, till the boy was able to live on his own. I think there was a suggestion that the father threw the boy out when he was too old to be useful. The boy himself was not evil, but was in thrall to the truly heartless father.
 * The British humor film Keeping Mum has what might be considered a (on the whole) well-meaning (though definitely not good) snake. Grace (aka. Professor McGonagall), the new housekeeper (who happens to be an elderly released murderess) becomes genuinely grateful that the family she has moved in with is happy and grateful she's come, particularly Walter (aka. Mr. Bean). Compounded with her, she decides to help the family and goes about being a decidedly murderous Mary Poppins to the Goodfellow family. First killing a dog that kept Gloria up, then the owner when he snooped, and finally Gloria's peeping tom paramour because he was causing Gloria to destabilize the family. All in all, she did the family a world of good, however
 * In Toy Story 3, Buzz and Woody risk their lives to save  from the dump shredder, even though he had previously tried to kill them. Then, at the dump incinerator a few minutes later, it's   turn to repay the favor. Instead, he
 * In the backstory of Mirror Mask, the Queen of Light took in the Evil Princess, who repaid her kindness by stealing the charm that kept the Queen and the realm alive.
 * And let's not forget that after leaving the world of Mirrormask and trapping its creator inside, she was systematically destroying the paintings in the real world that were its anchor. All just to get away from smother dearest.
 * In the opening scene of Halloween 5: The Revenge of Michael Myers, Michael is nursed back to health by a hermit after falling down a mineshaft and nearly being shot by local authorities. Then, a year later, he wakes up from a coma and murders the hermit.
 * In the 2007 remake, when Michael escapes the institution, the only security guard who showed him compassion and kindness throughout his fifteen-year incarceration is given an extremely brutal and over the top murder: tossed around like a ragdoll, head dunked in sink four times, and finally head squashed by thrown TV. In contrast, the other guards, most of whom bullied and demeaned him, are typically stabbed or neck snapped.
 * In the Coen Brothers film Millers Crossing, Tom is supposed to take Bernie into the woods and kill him (Bernie grifted the wrong mobster), but when he is supposed to do so, Bernie's constant pleading and weeping convinces Tom to take pity on him, and he lets him go. Shortly thereafter, Bernie shows up at Tom's home and proceeds to blackmail him by threatening to walk around in public, even though that would probably get him killed by somebody with more the stomach for it than Tom. While pleading, Bernie even makes the argument that he shouldn't have to die for grifting, because "I see an angle, I take it," somewhat paraphrasing the Scorpion's excuse, "it's my nature."
 * In The Thief of Bagdad, Abu, while stranded on a deserted beach, discovers a bottle. Opening the bottle, he unleashes a huge genie, who because of his imprisonment grew to hate those who lived free and swore to kill his liberator. Abu tricked the genie into returning to his bottle and threatened to toss him into the sea. The genie was then able to regain his freedom by granting Abu three wishes.
 * This is pretty much lifted directly from the Tale of the Fisherman and the Genie in the Arabian Nights.

Literature

 * One version of the trope-naming story (Brer Possum and Brer Snake) ends with the line, "Well, you knowed I was a snake when you put me in your pocket!"
 * Death Gate uses this as a rather brutal subversion of Love Redeems.
 * An interesting inversion takes place in The Executioner. One-Man Army Mack Bolan sets off on a Roaring Rampage of Revenge when his family dies in a murder/suicide indirectly caused by Mafia loan sharks. A faction of the New York Mafia Commission, pointing out that their own organisation was created when former enemies made peace, suggest offering Bolan a deal in which he would now work for them. A rival faction is opposed, with one mob boss who's missing several fingers mentioning a pet alligator he tried to raise as an allegory. Although an undercover Fed urges Bolan to take the deal he rejects it, saying he can't let the Mafia even think that they've won.
 * Orson Scott Card used something similar in his story The Princess and the Bear. Having attempted to redeem the Evil Prince, the princess If this sounds like a Family-Unfriendly Aesop, it ought to be mentioned that the prince and the princess follow the standard cycle of an abusive relationship.
 * If any lesson is to be taken from Otherland, it's this: never date anyone whose last name is Dread. And who likes to be addressed as "More Dread." And whose idea of romancing you is setting a priest on fire for your amusement ...
 * The villain Achilles from Bean's side of the Ender's Game series has a pathological need to kill anyone who has ever seen him helpless -- including but not limited to a girl who lifted him from low-ranking thug to leader of a prosperous gang, a nun who got him off the streets entirely and enrolled in a good school, and a doctor who dared use anesthesia to help fix his bad leg.
 * Subverted in Les Misérables, as Jean Valjean is taken in by the priest when no one else will after being paroled following nineteen terrible years in prison. Valjean assaults the priest and steals his silver in the night, but while escaping, he is caught by the police as a suspicious character. The priest tells the police that he gave Valjean the silver, and lets him go. This act of kindness actually changes Valjeans nature, as he strives to be good in return for this second act of compassion. It's shown that being put in prison had thoroughly corrupted him in the first place. His crime was stealing bread to feed his sister's children, for which he got five years, with the sentence extended for every time he escaped.
 * Redwall's Veil Sixclaw repaid the Abbeydwellers for saving him by attempting to poison one of them. Then again, they may have saved his life but even before he attempted to kill them they always treated him as if he was going to anyway. His foster-mother Bryony, the only one who trusted him, considered this as a Freudian Excuse, but it didn't help.
 * Considering that they intentionally gave him a name that was an anagram of "vile" and "evil" it looks like they had him pegged as a Viper from day one; whether this is a Self-Fulfilling Prophecy or a case of Always Chaotic Evil is probably up for debate
 * Worse yet, even at the end of the book, he himself feels like he is evil or just born bad, even though he saved Bryony, sacrificing himself to do that. It's also notable for being one of the few books where Redwallians are portrayed in a less-than-sterling light. They're good in themselves here, but their actions toward Veil are ambiguous at best, just as he is ambiguously good or evil. Bryony also seems very uncertain about him even afterward, and both seem to think she should have let him go long before.
 * This trope also applies to Chickenhound of Redwall, who is kindly taken in by the Abbeydwellers after they find him lying muddy, bloody, and unconscious in the middle of the road. He repays the gesture by stealing a bunch of random trinkets and, although in his defense the latter was mostly an accident. About the only thing he does do that's him being nice to the Redwallers is tell them about  , which turns out to be incredibly useful, but wasn't entirely altruistic on his part.
 * Pretty much any vermin Redwallers ever take in or help fit this trope. Salamandastron has Dingeye and Thura, who eventually  and then flee the Abbey, stealing Martin the Warrior's sword and infecting the place with Dry Ditch Fever in the process.   was accidental and the Dry Ditch Fever was inadvertent, but the sword stealing was their decision, albeit while in a state of panic. The Bellmaker has the Redwallers take in two wandering corsairs, a captain and his Minion With an F In Evil. The captain ends up   and stealing a trophy cup, but the trope is inverted when the minion ends up
 * In The Riftwar Cycle, Tal asks Nakor how he can swear an oath to serve the evil Duke Kaspar, who wiped out his people, as part of a ploy by the good guys to spy on him. Nakor tells him the "scorpion and the frog" version of the story and explains that he won't have to break his oath to Kaspar, because it's in Kaspar's nature to betray him first, which would render Tal's oath void.
 * Aristophanes quotes Aeschylus in The Frogs as saying: "Best not to rear a lion's cub in the City, but if you do, its ways must then be served."
 * In The Eye In The Door, the "viper" character tells this fable to the "farmer" character in order to explain his actions.
 * In Wuthering Heights Nelly Dean comes close to invoking this when she says that Heathcliff was "harbored by a good man to his bane," implying that Mr. Earnshaw inadvertently ruined his family by taking pity on a homeless orphan.
 * In the Guardians of Ga'Hoole series, Simon saves Kludd from a death by drowning/having his face melt, only for Kludd to.
 * Invoked and eventually subverted in Battle Tech's Blood of Kerensky novels. Anastasius Focht, the commander of Com Star's military mentions a variation of the fable to the Primus, suspecting her of trying to politicize his upcoming battle with the Clans and attempting to warn her that her penchant for doubledealing could defeat the treaty he was negotiating with them. She promptly plans to betray the Clans and the Inner Sphere at the same time, even calling the operation Scorpion, but the plan fails due to a Mole in the First Circuit, and is assassinated for her betrayal.
 * Referenced in ''Mara Daughter of the Nile". "I plucked a lily from the gutter and it has turned into a viper in my hands." From Sheftu's perspective, he aided a fugitive slave girl and gave her a purpose and a future (and also fell in love with her)--only for her to turn around and betray him to the Queen. (Mara's side of the story is a little different).
 * Given an interesting twist in a chapter header in Agatha H and The Clockwork Princess.

Live Action TV

 * Anyone who talks to Sylar on Heroes. Ever.
 * With the caveat that most of the people that try to work with Sylar are decidedly evil themselves. So, it's basically a case of the Scorpion and the Viper.
 * In the two-part Star Trek Voyager episode "Scorpion", Captain Janeway plans a temporary alliance with the Borg in order to combat Species 8472. When she asks for Chakotay's personal opinion, he relates the parable of "The Scorpion and The Frog" mentioned in the page quotes, though with a fox in place of the frog. Oddly, the story as told is more tragic than the normal telling, with the scorpion apologizing for being unable to help its nature, when the Borg would have no such compunctions.
 * In the earlier series Star Trek the Next Generation Q actually uses this against the crew when he's turned mortal by the continuum, choosing a human form and going to them for help, assuming that their values and willingness to forgive "almost any offense" will mean they are willing to protect him from the variety of less-moral creatures he has tormented in the past, and who are willing to take advantage of his newfound humanity. He's not entirely right in this assumption, but right enough for subverting this trope in "Viper part" too, when.
 * Two episodes of Highlander the Series featured an 800-year-old immortal named Kenneth, who is trapped in the body of a 10-year-old boy (Immortals stop aging whenever they are "killed" for the first time). Kenneth's standard procedure is to pretend to be a helpless immortal child who only recently found out he was immortal, and when he's taken in he waits for an opportune time and kills his protector from behind, stealing their power.
 * In an episode of MacGyver, the female antagonist is hanging from a ledge. MacGyver is all Take My Hand, but the woman stabs him, causing him to drop her to her death. Pete tells MacGyver the tale of "The Scorpion and The Frog" to calm him when he questions why she would do that.
 * Invoked in the Chinese TV adaptation of The Prince of Tennis, where Hai Tang (whose nickname on the court is "Viper") recounts this story as the reason why his teammates shouldn't get too friendly with Long Ma.
 * In Being Human, after
 * The Bill. An elderly bank robber is caught in the act, and when asked why he'd risk the long prison sentence at his age relates the story. The episode ends with him saying "I'm a scorpion." (i.e. It's my nature).
 * In the first episode of Supernatural, a ghost is killing men who see her hitchhiking and pick her up. The trope is arguably averted because her victims have an ulterior motive--she is smoking hot and the drivers are hoping the pickup turns into a hookup.
 * In the Northern Exposure episode "Gotta Sing", Shelly performs a jazzy version of Al Wilson's "The Snake" while warning Maggie that you cannot and should not expect unpleasant, mean people to not be unpleasant and mean.
 * Lifetime Movie of the Week Bad to the Bone is an adolescent version of all those Film Noir capers featuring a (mostly) good man and an evil woman. A teenage girl wants her rich boyfriend dead so that she can get all his money, so she lies to her brother that the boyfriend is abusing her. The brother shoots the boyfriend dead in an alley, and soon afterward both brother and sister are arrested on suspicion of the murder. The brother makes clear early on that he is willing to take all the blame for the murder in order to save his sister from life imprisonment, or possibly even execution. The sister repays him by making bail and disappearing two weeks before the trial even begins, leaving her brother to stew in his jail cell while she's living the high life with various other gullible boy-toys. (Even then, the brother refuses to testify against his sister at his trial, and it takes him until almost the end of the movie before he realizes what a patsy he's been.) At one point we see the bad girl telling her "life story" to one of the rich male companions she's snagged (she's concocted a Multiple Choice Past to go with the false identity she's assumed), and she says that she had a brother once, but he died! What a class act.
 * In the backstory of Power Rangers Time Force, Big Bad Ransik was rescued and given life-saving medical attention by Dr. Ferricks. He responds to this kindness by setting the doctor's lab on fire and leaving him to die.
 * An episode of Scrubs has J.D. pull a splinter from the Janitor's toe, and even bring up the parallel to Androcles' Lion (with the Janitor saying the story ends with the lion killing and eating the mouse anyway). The Janitor makes a show of offering unwanted payback, and finishes off by pointing out that J.D. could have just asked for him to stop messing with him (and steals his stethoscope when he tries to).

Music
""I saved you," cried the woman, "and you bit me, but why?
 * Given a Perspective Flip in Nick Cave's song "Fable of the Brown Ape", where the snake is portrayed as a victim rather than a threat.
 * Al Wilson's "The Snake" is a variation of the trope-naming story set to music. A tender-hearted woman finds a half-frozen snake, and takes it home with her and warms it up, but is bitten in much the manner of the farmer.

You know your bite is poisonous and now I'm gonna die."

"Oh, shut up, silly woman," said the reptile with a grin,

"You knew damn well I was a snake before you took me in." "

- The Snake


 * Megadeth song "The Scorpion" alludes to "The Frog and the Scorpion" in the refrain. The lyrics are otherwise more about a figurative scorpion rather than a literal one.
 * The song "The Snake" by Mediaeval Baebes is sung in Old Spanish and matches this trope almost completely with the difference being that the snake starts growing dangerously big and when the farmer tries to kick it out of his house, it squeezes him to death instead of stinging him. The lyrics apparently come from a fable from El Libro de Buen Amor (The Good Book of Love) by Juan Ruiz, Archpriest of Hita from the 14th century AD/CE.

Mythology
" Scorpion: "Better we both should die than my enemy should live.""
 * The Scorpion and the Frog, an ancient African & European fable commonly misattributed to Aesop is equally if not more popular than the trope namer, but also deals in how evil is ultimately unconsciously self-destructive. Sometimes the moral is the slightly more digestible.

"Frog: Now we shall both die! Why on earth did you do that?
 * The CCG Legend of the Five Rings has a twist on this story.

Scorpion: Little frog, I can swim."


 * Why do the Scorpions wear masks? Because their founder wore a mask after hearing this. He didn't want anyone to see he COULD NOT STOP SMILING!
 * A variation involves the Lion and the Unicorn. The two were enemies, but the Unicorn agreed to let the Lion borrow its horn. The Lion then ambushed the Unicorn and stabbed it with the horn. When the Unicorn asked why the Lion did this, the Lion responded by asking why the Unicorn trusted its worst enemy in the first place.

Professional Wrestling

 * Happens again and again whenever the heel is a Dirty Coward. You can bet farthings to fritters that as soon as the face has overpowered the heel, he'll be on his knees crying: "Nooo! Noooooo!" Any face who is not Genre Savvy enough to just hit the guy anyway after that will be deservedly punished with a thumb to the eye or an even more painful indignity. (If Ric Flair is the heel, the odds of this not happening are pretty much nil.)
 * In Ring of Honor, CM Punk started as a heel, turned face, and was receiving massive cheers by the time he won the belt, at which point he made a promo referencing Aesop's story and declared "I'm still a snake, you idiots!", declaring that he was going to take the title belt with him to the WWE, and signing his WWE contract on the ROH title belt. Of course, as an indie darling and a good performer, he was Face for over a year (and not just with the smarks) since hitting the WWE...and then he assaulted fan favorite Jeff Hardy and stole his title after Jeff had been champion for about five minutes.
 * As part of a Continuity Nod, he did basically the same thing in WWE. This time, with a very interesting result.

Tabletop Games

 * Subverted in the game Legend Of Five Rings. The classic story of the frog and the scorpion is told, but when the frog asks the scorpion why he doomed them both, the scorpion replies,

Video Games

 * A variation: Knights of the Old Republic, Jolee Bindo, having lived as a hermit on Kashyyyk for twenty years, helps the player character out and then follows you offworld. For a good while he claims that his reasoning is that he'd finally gotten sick of the planet, he wanted to see the stars again. But as he gets to know you he tells you a parable about a young man who one day finds a snake in his village. He follows the snake, helping it away from the village and into a great desert. Without food or water to be seen, the snake bites the young man. The snake then asked why the man followed him, and the man replies; "Did I follow you? I thought I was leading you away from everyone else!" Considering that the player character is, that parable might or might not apply to you. At any rate, this particular snake can choose whether or not to bite.
 * is the reason Ratchet is the last Lombax in the universe.
 * In Age of Wonders the Keepers attempt to raise some goblins to be good. The Cult of Storms has no trouble convincing the goblins to riot and help kill the Keepers' leader.
 * In Dragon Age: Origins was left for dead when the darkspawn massacred his squad. When he comes to, he is not happy with surviving and slaughters the villagers who picked him up and nursed him back to health in blind rage.
 * In that case, he doesn't fly into a rage at surviving, but at having lost his sword, which is very important to him as a Proud Warrior Race Guy. He follows the player as his own Redemption Quest because of this.
 * If the player opts to complete the quest "Run, Goodsprings, Run!" in Fallout New Vegas, this is the Doctor and the Courier, respectively.
 * In Batman Arkham City, Batman saves a Two Face thug from being lowered into a vat of molten steel by Joker Thugs. No sooner does Batman take his eyes off the thug does he try to knock you out.
 * Heavy Rain. Without spoiling anything, suffice it to say that during the ending showdown with the Origami Killer, it is entirely possible that the fight will end up on a tall structure, and properly dodged or countered attack will leave the killer hanging by his fingertips over a deadly drop. The killer will humbly ask for your aid, and you have the option of pulling him to safety or letting him fall. Should you choose the former, the killer will give you a sincere-sounding word of thanks before immediately resuming his attempts to kill you. Of course, even the most Genre Blind player would see this outcome a mile away, but the killer is so Evilly Affable that most players are tempted to at least take a chance on saving him. A testament to how well-written and -acted the game is.
 * If you killed the Rachni Queen in the first Mass Effect, the Reapers create a husk Queen in the third game to produce Ravagers. The Queen is understandably enraged at having been created as a monster to create more monsters, and wants to help fight the Reapers... supposedly. She ends up betraying you, not only taking away the Assets she provided but also decimating your Engineering Corps.
 * If you saved the queen...this trope is averted.

Webcomics

 * In Drow Tales, Ven'nedia accepts the highly demon tainted Creepy Child Kharla'ggen into their "clan" (at that point more a group of tainted drow seeking mutual protection and understanding) to try and help her adapt to her condition and live a normal life. She and her daughter treat her like family, and even normalize her enough that, while still incurable, she settles down. Then their clan is attacked and nearly destroyed, and she kills all the invaders singlehandedly. When rival Sene'kha proposes using Kharla'ggen as a figurehead leader she is opposed, and when voted down tries to run away with her daughter Kiel'ndia ... only to have Kharla'ggen turn her into a living puppet, put on display over their main entrance to scare enemies (and allies).
 * Of course, Kiel doesn't hold Kharla responsible for this. Sene'kha on the other hand...
 * Bob the Angry Flower tells it as it is.
 * The parable is used as the basis of a weapon's backstory in Keychain of Creation. This is Exalted, even the swords have cool histories and vendettas.
 * The Scorpion and the Frog parable, above, inspired Vriska Serket in Homestuck (or rather, she inspired it), as her motif is scorpions and has a self-destructively malicious nature. Appropriately enough, she
 * Freefall has this happen to Sam in this strip.

Western Animation
"Eddie Deacon (the flipper boy): Why'd you do it, Croc?
 * Avatar: The Last Airbender. While Aang, Sifu Thou Shalt Not Kill, consistently saves Zuko, Sokka, who's spent his whole life in a war, asks why they should help him in the first season finale, given that all the previous times they've saved him or shown mercy he's tried to capture Aang.
 * In the third season
 * In a less extreme example, during Zuko's exile in the Earth Kingdom, a woman and her mother take him and Iroh in for dinner. As they leave, Zuko steals their Ostrich Horse.
 * Also, in "Imprisoned", Haru uses his Earthbending to save an old man from a cave-in. Later that night, the old man rats him out to the Fire Nation and gets him arrested.
 * Batman the Animated Series: Killer Croc escapes while escorted by train to a prison, Batman in hot pursuit. They fall off a cliff and are knocked out. Croc wakes up in a secluded home owned by former circus performers. It's Croc's perfect chance to start a new life. Naturally Croc claims Batman is evil to get their help in capturing him. Then Croc captures everyone and plans to kill them and run off with their retirement money. When he's eventually foiled, he does seem a little regretful as he's taken away.

Killer Croc: Something you said, kid. I was just being myself."


 * The Simpsons
 * Lisa makes it her goal to help Burns rebuild his lost fortune in a socially responsible way. He takes to her teachings with zeal, but in his efforts to follow her instructions he creates a recycling plant that strip mines ocean life into an all purpose slurry. It ends with the memorable scene of Lisa running house to house begging people not to recycle!
 * It then happens again, many seasons down the road, when Burns is brain-damaged and has lost his memory. Most of the Springfieldians take advantage of this to get revenge on him for everything he did to them. Lisa takes pity on him, and ends up restoring him to his former, evil self, with the added lesson that hatred is the only thing keeping him alive.
 * An earlier episode had Marge take an interest in reforming Jack Crowley, a prisoner convicted of armed robbery (voiced by Michael Keaton) by encouraging his casual interest in art. The warden agrees to let Marge take Jack into her home and help him find a job as a mural painter. When Marge hears that Principal Skinner wants a mural painted for Springfield Elementary, she suggests Jack for the task. But Skinner forces him to paint a treacly, cutesy scene instead of what he actually wanted to paint - and then, to add insult to injury, Skinner has Jack take all the blame when the mural proves unpopular. Jack has to be restrained from physically assaulting the principal, and soon afterward a plot to burn down the school is uncovered. Marge finds Jack hiding in the playground and accuses him of going back to a life of crime; Jack lies that he's innocent, prompting Marge to believe him and to help him escape. Marge's reward for this is seeing Jack pour gasoline on Skinner's car and light that on fire in full view of everyone, laughing diabolically. Jack is quickly arrested and finally confesses to indeed starting the school fire, but not the car fire, leaving Marge disgusted.
 * The episode "Action Figures" of Superman the Animated Series featured a couple of kids sheltering an amnesiac Metallo, who they think is a good robot who can be like Superman. In the beginning, he does do good and helps save the kids and trucker, but as more of his memories return he reverts to his evil persona. In 'gratitude' for helping him, he tries to kidnap the kids and leave the volcanic island their parents are researching. When one of the children tries to appeal to goodness, he replies "Steel Man? Steel Man is dead! And so are you Superman!" Lois Lane later consoles the children with "He was good, when he was with you. Now all the goodness in him is buried, along with the rest of him".
 * An episode of Mickey Mouse Works involved Mickey rescuing Pete from the cold and warming him up inside the mouse's cabin. Being the greedy prick he is, Pete reveals he only pretended to be freezing to death as he and his cousin take over Mickey's cabin. Of course, being a cartoon about Disney's beloved mascot, Mickey not only managed to turn the two against each other, but, in the end, tricked the criminal dimwits into turning themselves into the police.
 * On Jimmy Two-Shoes, Jimmy agrees to care for a weavil he believes to have injured, despite Beezy's warnings that weavils are Always Chaotic Evil. Indeed, the weavils take full advantage of him, slowly transforming him into one of them.
 * In the oft-disputed third season of Gargoyles, a common tactic the villains used was having someone pretend to be in danger in order to lure the heroes into a trap.
 * In an episode of Family Guy, Lois finds out she has a brother (voiced by Robert Downey Jr) who was put in a sanitarium by her parents after a traumatic event and kept a family secret. Lois, assuming her awful parents were just being awful again, brings her brother home to live with her. It turns out he's a dangerous psychotic. He goes on a killing spree that ends with him trying to kill Peter.

Other

 * Parodied in Richard Bartle's children's book parody, the SO Book of Spoons, in the story about The Farmer And The Fox.
 * The story of Yallery Brown.
 * This is the reason people are told never to pick up hitchhikers.