Is your hero an [[DesignatedHero unsympathetic bastard]]? Does he need some good CharacterDevelopment to make him more likable, but you don't know how to express his change of heart?

Well, as it turns out, you can do exactly that: stick a new heart in your character's chest, and watch him suddenly improve! He'll care more about people, he'll act like less of an asshole, or maybe he'll even take on personality aspects of the person who gave him his heart.

Depending on the genre, this may involve actual heart transplants, but it also counts symbolic hearts (in the case of things that do not literally have the organ, or who want to make the transfer without the {{Squick}} involved with a literal heart transplant) or heart-like objects (such as the pneumatic "heart" of a robot). Note that the [[IncrediblyLamePun change of heart]] is not always [[HeelFaceTurn for the better]]. In some cases, the new heart makes you more... [[FaceHeelTurn well, heartless]].

This trope can also be played heroically, if one character nobly sacrifices his or her heart to another character who is not necessarily bad. In these cases, the emphasis may be on the sacrificial giving of the donor, rather than on any potential changes in the recipient's personality. The two versions of the trope aren't necessarily exclusive: if the noble character sacrifices his or her heart in order to rescue or convert an evil character, the "bad" nature of the recipient serves to highlight the generosity of the sacrifice.

For less literal changes of heart, see HeelFaceTurn or FaceHeelTurn. For other heart-related tropes, see HeartTrauma and CardiovascularLove.
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!!Examples

[[foldercontrol]]

[[folder: Anime And Manga ]]

* ''Anime/AngelBeats'' has the rare heroic example of [[spoiler: Otonashi donating his heart to Tenshi after dying]].
* In ''BlueSubmarineNumberSix,'' it turns out that [[spoiler: the doctor everyone blamed the world's problems on removed his own heart and used it to power the Earth's destabilizing magnetic field.]] So, in this case, the one who received his heart was [[spoiler: the planet]].
* This is the premise of ''Manga/AngelHeart'': receiving a heart transplant changes the life of an assassin.
* In ''BusouRenkin'', [[spoiler: the villain Victor's StartOfDarkness began when he had his heart replaced by the experimental Black Kakugane.]]
* In ''Anime/ScienceNinjaTeamGatchaman'' the Condor has to have his heart replaced.

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[[folder: Comics ]]

* In the ''{{Superman}}'' {{Verse}} Metallo has a Kryptonite heart. In various versions he may be a robot, cyborg, or just have an artificial heart.
* In ''CreatureTech'', an alien symbiont knocks Dr. Ong unconscious, rips his heart out of his chest, and attaches itself over the hole, serving as a replacement heart.

[[/folder]]

[[folder: Fan Fic ]]

* In ''FanFic/MegaManDefenderOfTheHumanRace'', to cement his character development, [[spoiler:[=ProtoMan=] offers his own internal regulator/heart to save Mega Man]].

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[[folder: Film ]]

* ''Film/{{Dragonheart}}'': Draco gave half his heart to the prince hoping it might redeem the prince from the ways of his wicked family. [[spoiler: It didn't work]].
* A sort of example, Tony Stark from ''Film/IronMan1''; though the heart didn't actually come from someone (or something) else, getting the arc generator put in his chest did symbolically represent his assumption of the role of Iron Man, thus fitting the trope.
* In the movie ''Heart Condition,'' a heart transplant patient ends up stuck with the ghost of the donor, a black man whom the recipient hated because he was racist, and because the recipient a cop and the other guy a lawyer. This of course brings about an emotional change of heart as the movie progresses.
* In ''Film/RepoMen,'' the main character only acts like a decent human being after losing his heart and having it replaced with a mechanical heart.
* In ''Film/ReturnToMe'', Grace receives a transplanted heart that previously belonged to Bob's late wife. Although the movie is mostly not supernatural, there is one brief moment which suggests a connection between Grace and Bob due to the transplanted heart.
* A heroic version occurs in ''Film/TerminatorSalvation''. [[spoiler: John Conner gets mortally wounded and Marcus makes a HeroicSacrifice giving him his own heart]].

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[[folder: Literature ]]

* In ''Clockwork'', by Creator/PhilipPullman, a character's mechanical heart is winding down, threatening his life.
* In ''Literature/HowlsMovingCastle'' (both the anime and the novel) [[spoiler:Calcifer]] had swallowed [[spoiler:Howl]]'s heart as part of an old contract between them. The ending involves the heart being returned to its original owner, with some improvement of said owner's character.
* In Meredith Ann Pierce's book ''[[Literature/TheDarkangelTrilogy The Darkangel]]'', two characters switch hearts in an attempt to save one of them at the expense of the other's life. [[spoiler: They both live, because as it turned out, there was a way to revive the vampyre's heart without Aeriel giving up hers.]]
* The titular warlock in the ''Literature/HarryPotter'' fairy tale ''The Warlock's Hairy Heart'' attempts this. It doesn't go well for anyone.
* One of the older print examples is the TinMan from ''Literature/TheWonderfulWizardOfOz''. Because of the curse on him and the EmergencyTransformation he underwent to survive it, he does not have a proper heart. He wants to ask the Wizard for a replacement so he can return to his girlfriend and become a proper husband for her. He succeeds in his task and gets a [[MagicFeather sawdust and silk one]]. [[spoiler: Too bad his girlfriend was seeing someone else on the side, and got married when he was rusted by the roadside.]]
* In ''Literature/HowTheGrinchStoleChristmas'', the Grinch has a change of heart about stealing the Christmas gifts from Who-Ville after he heard the Whos celebrate anyway and his heart grows three times as large as it was before.
* In ''Three Fat Man'' by Yuri Olesha, the titular villains demanded from a scientist to replace the heart of their future heir with a heart of iron in order for him to grow up the way they wanted. When the scientist tried to explain it cannot be done, they put him in a cage. A rumor eventually spread among the population that the Fat Men ''did'' replace the boy's heart (a completely false one - the boy was shown as kind, although rather misinformed).
* In the MagicTheGathering ''Scar of Mirrodin'' block novel, Venser gave his heart to Karn, whose original Heartstone was full of Phyrexian Glistening Oil. This allowed Karn to leave New Phyrexia and begin work in removing their evil once again.
* Creator/WilhelmHauff's story "The Marble Heart" is a about some giant (or perhaps a [[DealWithTheDevil devil]]) who offers people wealth, but in return, they must have their hearts replaced with marble.

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[[folder: Live Action TV ]]

* In the series finale of ''{{Smallville}}'', [[spoiler:Darkseid takes Lionel's heart out and plants it in the Lex clone's body]].
* Occurs in the "Brown Betty" episode of ''Series/{{Fringe}}''.
* In ''Series/StarTrekTheNextGeneration'', Captain Picard got in a fight with some surly Naussicans as a youth and got stabbed right through the chest. Now he's got an artificial heart. During a near-death experience in a later episode, he was asked by Q if he would like to change that part of his past that lead up to that (and the subsequent malfunction of the artificial heart years later); however, by doing so, he wound up becoming a person who never developed any guts or took any risks.
* Played with in an episode of ''TheRickyGervaisShow''. In the episode, Karl talks about a made-up TV show he came up with called "Look What We Can Do With Science" and has him explaining how he thinks human organs can just be either removed or replaced. He then states that they could replace a person's heart with a pacemaker, but Ricky is quick to point out that [[SubvertedTrope they don't really replace the heart with a pacemaker in real life.]]
* Occurs in ''KingdomHospital''. A shady, sleazy, overweight lawyer needs a heart transplant. Otto's dog finds a suitable heart, and Antubis transplants it.
--> '''Antubis''': Out with the old...and in with the new.
--> '''Lawyer''': AAAAAAAAAAAAAAAHHHHHHHHHHHHHHHH!

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[[folder: Mythology ]]

* This trope is in one origin story for Xuanwu (Genbu) of TheFourGods: as a mere mortal, he was a ruthlessly brutal butcher until he had a vision where he saw his horrifically disgusting insides being swapped out for much nicer ones. This resulted in him getting religion and becoming a saint, then going back to battle his old insides (which had become monstrous).

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[[folder: Tabletop Games ]]

* In ''DungeonsAndDragons'', ancient red dragon Ashardalon was already a arrogant monster of greed and violence when his heart was badly damaged in battle. But after he replaced it with a literal demon, Ammet the Eater of Souls, it got worse as Ashardalon basically became pure evil incarnate.

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[[folder: Video Games ]]

* In ''KingdomHearts,'' this is how a GrandTheftMe by BigBad Xehanort is preformed.
* In ''BrutalLegend'', Demon Emperor Doviculus keeps his defeated enemies' (including [[spoiler:Drowned Ophelia]]'s) hearts in his chest. It doesn't influence his NeutralEvil morality much.
* ''LegacyOfKain'' features the Heart of Darkness, which is heart of the last ancient vampire Janos Audron, ripped [[BeatStillMyHeart still-beating from his chest by Sarafan vampire hunters]] and christened as such. In the first game, the Heart simply acts as a healing item, but eventually it's revealed that the same heart was used by Mortanius the Necromancer to resurrect Kain, and it's also the only thing that can resurrect Janos himself.
* In ''VideoGame/TeamFortress2'''s "[[http://www.youtube.com/watch?v=36lSzUMBJnc Meet the Medic]]" video, the Medic accidentally destroys the Heavy's heart when trying to attach the Ubercharge device to it. He substitutes a larger heart from a "Mega Baboon" for it instead.
* ''VideoGame/TalesOfVesperia'': Raven's heart was replaced with a modified blastia after [[spoiler: he died during the Great War]], which took place 10 years prior to the events of the game itself. It not only sustains his life, it allows him to unleash the very same power as an offensive weapon; as seen during his Mystic Arte.
* During the ''Old World Blues'' DLC for ''VideoGame/FalloutNewVegas'', the player has his/her heart (and brain, and spine) removed and replaced by a synthetic one. Later on, you have the choice of keeping your powerful synthetic organs or putting your old ones back in. (Upgraded with a bit of tech, of course)
* In ''VideoGame/TheElderScrollsVSkyrim'', Forsworn Briarhearts are warriors who have had their hearts replaced with magical briar seeds. They are the mightiest warriors in the Forsworn's ranks, but the ritual deprives them of free will and makes them of little use as anything other than berserkers or battlemages.
* One mission in the Sega ''TabletopGame/{{Shadowrun}}'' game has you stealing a cybernetic heart in order to save the life of one of your brother's friends, because [[CyberneticsEatYourSoul he's installed so much cyberware on his body that his biological heart can't sustain him anymore.]]