The "Get Out of Jail Free" Card for the Noble Demon. Heat source for the Defrosting Ice Queen.
Villains can become popular enough that the fandom becomes sympathetic to them. However, meshing them into the main cast can be dangerous and disappointing if Good Is Dumb. This can also be unrealistic since even those downgraded to protagonists tend to be skeptical of anyone trying to help them. Some heroes wouldn't exactly be quick to accept them, either.
One way to handle this is to present another character to befriend them. Ideally this should be someone who could pose no threat or even be demanding, and depending how the plot goes, the recovering villain becomes fond of this other character and may draw stability from their presence. The Morality Pet may even be somewhat pathetic (and will be told so) but has often gone through some anguish to which the recovering villain can relate secretly, or reminds the villain of someone he lost long ago. They're usually upbeat, though they might go a littleoverboard sometimes.
This also makes for a convenient excuse to help the heroes if needed; an ex-villain can simply claim to have his own 'selfish reasons' and save face. Anyone messing with the Morality Pet can expect a full-on Mama Bear or Papa Wolf response from the ex-villain or antihero in question.
At the very least, they are the living recurring incarnation of Pet the Dog. Something to placate the audience regarding the hero's tolerance of the amoral character, while focusing on the true villains. (Unless they Kick the Morality Pet, that is.)
This isn't just for villains, either. Despite sidekicks being less popular in comic books nowadays, some writers pair them with Anti Heroes in an effort to humanize them.
Not to be confused with a magic-user's familiar, the creature type of which often reveals the kind of person who owns it, though if the magic-user is fond of the familiar and treats it well, it could very well be a Morality Pet.
If the Morality Pet dies or disappears and this causes the villain/anti-hero to revert back to his or her old ways, the Morality Pet was acting more like a Morality Chain.
Examples:
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Anime and Manga
Reimei No Arcana: Nakaba is one for both Loki and Caesar. Vernas' younger sister Lemilia is one for Vernas.
Nabari No Ou: If it weren't for Gau, Raikou would basically be a villain.
Yachiru Kusajishi from Bleach is the uber-cute child vice-captain of Kenpachi Zaraki, one of the most violent and physically monstrous of the 13 Captains that rule Soul Society. Kenpachi may be a savage now, but before he took in Yachiru he was little more than an animal with a sword. All he did was kill; he didn't even care that he had no name. He may be on the bottom of the morality ladder now, but before meeting her, he wasn't even aware it existed.
Note that Yachiru enthusiastically encourages "Ken-chan!" to go wild when he gets a chance to fight. And is STILL a positive influence on him. Somehow.
Rangiku towards Gin. Especially evident when it's revealed the only reason why he joined Aizen was to get revenge because Aizen's underlings and he injured Rangiku in the past.
Lilinette seems to serve as this for Starrk. When the 9th Espada was killed, Starrk went right on sleeping, until Lilinette woke him up and asked him what he was going to do about it.
In Inu Yasha, Rin's humanizing (so to speak) effect on Sesshoumaru.
Kohaku became a bit like this for Kagura. Especially notable because later, she ends up dying for him.
Mokuba Kaiba from Yu-Gi-Oh! sometimes takes this role, making Seto Kaiba somewhat approachable.
Most Yu-Gi-Oh villains have something like this. Pegasus had his dead wife Cynthia/Cecilia, but more of a Dead Little Sister. Marik had his sister Isis and his adoptive older brother Rishid/Odion, Dartz as well. Bakura has 99 metaphorical dead little sisters, which prompted him to go on such a wild Roaring Rampage of Revenge that he made a Deal with the Devil.
In the Fullmetal Alchemist manga, the serial killer Scar obtains May Chang, an adorable little munchkin girl who is an active practitioner of a form of alchemy, the very art he despises.
Wormmon to his partner Ken Ichijouji from Digimon Adventure 02, after Ken's repentance. (Unlike the standard depiction of this trople, when Ken was evil, Wormmon was basically the dog, as in "kick the.")
Not to mention a cat with a Morality Pet wizard in the original.
And the cat's eventual partner replaced that wizard when the poor wizard kicked the bucket. A human being a morality pet to something normally considered a pet?
The girl reached morality pet status before that. The assigment was to kill the kid, but when the time came, she just couldn't.
In Magical Girl Lyrical Nanoha, Hayate acts as a morality pet to the Wolkenritter, especially Vita, who was rather hostile to everyone before Hayate appeared, and Signum, who was extremely serious and emotionless about her "job".
Lelouch doesn't really treat his "subordinates like water" - he doesn't care too much about their lives (other than Kallen's), but he is perfectly aware that his numbers are greatly overshadowed by Britannia's. He's simply not stupid enough to waste them. Of course, that doesn't stop anyone from thinking that it's the truth. And boy, does that bite everyone in the ass when Schneizel gets a hold of that.
Not only is she his Morality Pet, but also a large part of his raison d'etre. As in, quite literally, he's not sure whether it would be worth living if she has to live in this quite unkind world.
And she's not just Lelouch's morality pet: To a degree she's also Suzaku's once he gets far enough on the Knight Templar side...
Euphemia is also the Morality Pet of her older sister Cornelia; Cornelia's doting on her younger sister is her main point of humanization.
Speaking of C. C., one might say that Lelouch becomes a Morality Pet to her, in that she begins to feel human emotions once again while in his presence, even against her own admission sometimes.
Something of a subversion: Ralph in Soukou No Strain is kind to the living Emily and protects her from the rest of the Deague, but when he throws a coup on the ship and kills everyone but Emily and Medlock, it's clear that even that won't save him. He's insane, and if he's allowed to live, he'll turn on Emily just like his real little sister, Sara. He does find a glimmer of sanity near the end, though.
Dragon Ball 's straight application of this trope would have to be Piccolo and Gohan. While Goku's influence means Piccolo is no longer evil, essentially adopting and training Gohan made him proactively heroic.
Kazuma of Kaze no Stigma acts distinctly uninterested in helping people or saving the day unless he can extort a profit... but he cares a great deal about his little brother, Ren, and will not hesitate to save him...and he'll still charge you for it in order to keep up his image.
Alyssa Searrs is Miyu's Morality Pet in Mai-HiME. When Alyssa is introduced in episode 9, Miyu (who is the daughter/creation of Father Joseph, a priest at the school's chapel) is actually seen crying, genuinely moved by her young protectorate's singing abilities.
Of course, this is then subverted when you find out what Alyssa is a 'fake HiME' created by Searrs, who is a living remote control for an orbiting Kill Sat she is not afraid to use to hold the school hostage with. Oh, and she has a private army.
Garcia Lovelace is Roberta'sMorality Pet. Around him she acts like a nice Meido. When he's not around her, she tends to go crazy. Just look at the entry for Implacable Man...
This may have something to do with threatening Garcia being her Berserk Button as well, however.
Casca and Puck act as this for Guts from Berserk following the events of the Eclipse that shattered Casca's mind. Guts's concern for Casca's welfare in particular, and his need to protect her from the same demons that constantly hunt him due to her having the same Brand of Sacrifice that Guts has is about the only thing that keeps him from becoming completely consumed by his hatred for Griffith and the Godhand.
Another Apostle, the Count, had a daughter named Theresia, the only thing that remained of the family he had before he became an Apostle. While he still was very evil, his reactions to her show that he was quite more than a mere Complete Monster. When the Count lost against Guts, summoned the Godhand with his Behelit, and was told by Femto to sacrifice Theresia so he could be reborn or be condemned to Hell, he chose Hell over handing poor Theresia over.
In a tragic aversion Caska and the band of the hawk were almost this for Griffith/Femto. First, when Griffith is permanently crippled and right at the breaking point to use the behelit he stops and considers the peaceful life he could have with Caska and calms down, her being the one thing that could make him give up on his ambition, but then when he overhears Caska planning to run away with Gutts it pushes him right off the edge. And then after becoming Femto when he returns to the physical world, he visits the memorial for the band of hawks and sees Caska just to prove to himself that he doesn't have a morality pet.
In Spider Riders, Princess Sparkle plays this role to Grasshop, eventually leading him to switch sides. Also, to an extent, Aqune to Buguese.
In Mahou Sensei Negima! (the manga, at least), Chachazero serves as a reverse morality pet to Evangeline. She's generally harmless when encountered, but being basically a serial killer in the body of a puppet, and designed as such by Eva, her comments and reminiscing about the bad old days demonstrate how much her creator's softened since. At times, Chachamaru verges on the straight version of this trope, but tends to stay in Battle Butler territory.
While he isn't really evil, Kaze's concern for Takeshi in Gantz definitely reveals kindness beyond his Arrogant Kung-Fu Guy image.
More notable is the effect Tae Kojima had on main character Kei Kurono, practically single-handedly turning him from a Jerk Ass to an outright hero.
Goldie Musou, arguably the worst Big Bad in the entirety of Gunsmith Cats, had a literal morality pet. In a flashback to her past, we see her grandfather give her a dog. After her parents are assassinated by a rival mob and she takes over in their stead, the dog growls at her and runs away. It smelled the chemicals on her hands from her mixing the prototype version of the drug Kerasene that she'd later use to make her criminal empire a dominant power. She even gets An Aesop from her grandfather's echoed words. "The truest test is to let something go. If it doesn't come back on its own, it wasn't yours to begin with."
Kurita could be considered Hiruma's (enormous) morality pet in Eyeshield 21. Sure, Hiruma inflicts his over-the-top violence on Kurita just as much as anyone else, but the choices he made because of Kurita really show the "heroic" aspect of his heroic sociopathy. Interestingly, Hiruma's actual pet, Cerberus, is, um. Not a Morality Pet. In fact, he's about as far from it as you can get.
In To Aru Majutsu no IndexLast Order acts this way for Accelerator who up to this point seemed like a mass murdering psychopath. Fairly credible job deconstructing his motives too. Though he's still a huge asshole if he doesn't like you. Then there was that one time he rescued a woman through the most violent means he could think of (slaughtering her captors to the last man).
Askeladd has a rather unusual one - the country of Wales, hismother's homeland that he would apparently rather die than see come to harm. He actually killed King Sweyn in front of his vassals to prevent him from invading.
Gunslinger Girl: Given that Guiseppe treats his cyborg assassin Henrietta far better than any of the other handlers, it's easy to forget that he too is a ruthless anti-terrorist operative, seeking revenge for his Dead Little Sister Enrica. Lampshaded in a scene where a female politician crippled by a terrorist bomb comments on how cold and frightening Guiseppe seems. Henrietta, naturally, protests that he's "the kindest man in all of Italy!" The politician wisely lets the matter drop.
A strange inversion happens in Ranma 1/2. Akane adopts an adorable black piglet as her pet, which unbeknownst to her, is Ranma's exceedingly violent and hostile rival Ryoga in cursed animal form. As a result of her affectionate treatment, and because he's incredibly lonely due to his Walking the Earth lifestyle, being the pet causes Ryoga to fall hopelessly in love with her. This greatly softens his character and partially contributes to his eventual Heel Face Turn (as he'll nearly always prioritize Akane over his grudge against Ranma, which allows for numerous Enemy Mine team-ups). Of course, there's the questionable morality of disguising himself as her pet in the first place, but hey...
From Shaman King: Hao's androgynous companion, Opacho, who uses toddler-speak and turns into a sheep. D'aww.
From Slayers: Not quite to the same extent, but Zelgadis acts far less like a Jerk Ass and more like a casual, if not aloof young man when Amelia's around. Compared to the other members of the group, he has an easier time softening up around her. Even though there is far less Ship Tease from them in the novels, he still gravitates toward her there.
A straighter example is Luke's bounty hunting partner Millina. She convinced him to end his assassination job, and he winds up falling for her to the point of gushing over everything she says since then.
In Axis Powers Hetalia, Switzerland is a gun-toting Gunslinger Jerk Ass. But when he's with his adoptive sister, the local Token Loli Liechtenstein, a completely different side of him emerges.
Zwei, the cold-blooded assassin in Phantom Of Inferno, adopts Cal, the kid sister of a dead hooker, in an attempt to protect her from his superiors. With a cute little kid tagging around behind him, he stops acting like the borderline villain he'd become and starts to ease back over into more standard Anti-Hero territory.
Cold, sociopathic gun-for-hire Katana from Gad Guard has the adorable little blonde girl Sayuri. Though he finds her annoying at first, after following him around for a while insisting she's his "fwend" and getting into danger a couple of times, she makes him see the error of his ways.
Double subverted in Yu-Gi-Oh! GX . Amon's little brother acted as one for him, but Yubel convinced him ditch his loyalty to the Garam group in order to fulfill his will and become king. After that, he sacrifices the woman who loved him and he loved back for power by unleashing Exodia. The double subversion comes in when he states that he will become king to make a perfect world so that no one suffers what he did nor can act on their deep, dark desires. This renders Yubel unable to feed off him, as he's not exactly 'evil.'
From Star Wars Manga, Darth Vader had a secret apprentice to soften him just a shade. No, not Starkiller. A Jedi child named Tao. Vader killed Tao's family, razed his planet from orbit, and spared Tao himself after being attacked by the child and sensing a lot of raw Force potential. Then he tried training the child, but since Defeat Means Friendship Tao refused to tap into his rage and hatred, endured Vader's frustration at this, and was eventually told that because of his weakness he was free to leave. ...Not something Sith say often.
And then the Emperor found out and had Vader mortally wound Tao, and for whatever reason Tao still didn't hate Vader, and was in fact glad that Vader was taking him to die on his homeworld. The homeworld that Vader razed. And when there, Tao saved him from a planet-hopping vengeful Tusken Raider, then told Vader that there was still good in him, before dying and making the Dark Lord feel remorse. This manga is quasicanon at best.
In Kenichi: The Mightiest Disciple, Kenichi's sister Honoka is pretty much the sole reason that Tanimoto doesn't act like a total jackass.
In Noein, cute little Miho serves as Jerk Ass villain Atori's Morality Pet. He was initially introduced as a Psycho for Hire villain but eventually gets bumped on the head and loses his memory as well as his Jerk Ass nature. He grew a fondness for her during this time, but after his memory (and true nature) returns and he starts being a jerk ass villain again, Miho is still able to bring back the dormant good and kindness in Atori, which eventually leads to his Heroic Sacrifice.
In Eureka Seven, Dominic is with the bad guys, sure. But his kindness to Anemone, who alternates between violently insane or just insane, makes it really hard not to feel for him, especially when they play up his Not so Different aspect with the hero of the story, who is also devoted to protecting Eureka, the girl he loves. And it ultimately works, as Anemone has a Heel Face Turn in the end.
Holland is a major Jerk Ass toward Renton for a good part of the series, but he has a major soft spot for Eureka, practically to the point of a Big Brother Complex. He has good reason to do so: she's part of the reason he came to his senses and abandoned the military death squads he served under.
The little kids seem to be this to Eureka. Flashbacks show her as having been cold, efficient, and mechanical, essentially a killing machine who only knew how to follow orders, when she was a part of the military. Then one day, she found three small kids that somehow survived the violent massacre that she just committed. Something about seeing them like that, vulnerable and utterly terrified, kick started something inside her, made her more human until she became the gentle, motherly girl she is when the series begins.
Inverted twice in Death Note, which has what could be called an 'immorality pet'. At first, Light (and the reader) believe that Ryuk, whose spare Death Note leads Light to become a Well-Intentioned ExtremistMagnificent Bastard, is his immorality pet. However, it's actually Light who is Ryuk's immorality pet, providing him with some interesting sick entertainment, and when Light no longer becomes interesting, Ryuk kills him.
Kind of played straight with Light's affection for his little sister Sayu and Mello's reaction to Matt's death, though.
Chief Kurama from Elfen Lied has Nana, a mutant girl who latched onto him as a father figure to provide some comfort in her life of horrific experiments. Eventually Kurama came to be just as attached to her, to the point where he's very much a Papa Wolf and might even be considered an Anti-Villain.
Mayu appears to function as this for Bando- although he has no issue with hitting little girls, he still shows up to save her from a rapist, which is arguably one of the only nice things he ever does.
And of course, there's Kouta's relationship with Lucy...
Keith Anyan in Toward The Terra has two, Sam Houston and Jonah Matsuka. Sam's interaction with Keith, particularly as the series progresses, always serves as an outlet for Keith's otherwise mostly repressed humanity; at one point Suena observes to herself that Sam is the only person Keith opens his heart to. Matsuka's relationship with Keith is a bit more tangled, but also ultimately humanizing.
Kuroshitsuji: Sebastian has his cat friends (and possibly Ciel himself depending on character interpretation—whether he genuinely cares about Ciel or if he wants nothing more than to eat his soul), Ciel has his household staff and Elizabeth.
Subversion: Lua Klein from Baccano! is a quiet, gentle Woman in White who seems like a perfect foil for her extremely enthusiasticPsycho for Hire squeeze Ladd Russo. However, she's really a suicidal masochist who seems to privately thrill at the idea of being murdered by Ladd, and Ladd's calm, sincere promises to kill her someday only emphasize his craziness.
However, it's played more straight when Ladd's arguably only redeeming act in the entire show is to throw himself off a moving train to save Lua, sacrificing his arm in the process.
Yuusei, the protagonist from Luck Stealer, is an assassin who will only kill criminals. This is because he wants to be a good person for the sake of his daughter.
Then there's Mukuro whose Heel Face Turn is coupled with the introduction of Chrome, his Spirit Medium/Vessel, who he is shown to be rather fond of to the point that she is arguably his Berserk Button.
While Durarara!!'s Shizuo Heiwajima isn't evil so much as he just sucks at being a good guy, it's noted that there are a handful of individuals (such as Tom, Kasuka, Celty and later Akane) that motivate Shizuo to go the extra mile to keep his violent temper in check. This is what keeps him from lashing out at the Yakuza when they go after and corner him. He doesn't care what the Yakuza do to him, but he realizes that if he attacks them (and thus destroys any chance of convincing them that he didn't kill three of their men), they're likely to go after his brother or friends to get back at him. This thought is just enough to hold him back.
Shinra ends up fufilling this roll for Celty, his father Shingen and surprisingly Izaya. It's to be noted that Izaya leaves Shinra out of his plans more often then not, and DOES try to help him during the Valentine's Day special in the novel. Naturally, this might have to do with the two knowing each other since middle school and Izaya did something to him that makes him shut up immediately whenever Shinra brings it up. Turns out that Shinra protected him during middle school from someone that tried to kill Izaya with a knife by taking the wound for him; maturally, this is probably the only kind thing that has happened in Izaya's life.
Yubaba's son Buu plays this role in Spirited Away, being the only person she cares more for than money. In fact, when Haku implied that he had taken Buu away (when he didn't), she went full Mama Bear on him to find out where her baby was.
Chihiro is this herself, able to bring the best out of the grumpy Lin and Kamaji and the cold Haku and geniunely befriends No-Face.
Rana serves as one of these for the villainous servant Airi in Queen's Blade. She literally starves herself to death (but she gets better) due to the kid's influence.
Haou Airen. Kurumi Akino became this for Uo Hakuron after saving his life when he was wounded in the streets of Tokyo. Even more so after she learns his Dark and Troubled Past, since she actively aims to become this for him. Not very Genre Savvy in regards to what kind of guy he is, eh, Kurumi?
Alfred, Robin and the rest of the "Bat Family" function as Batman's ties to family and sanity. It's worth pointing that their ideas of sanity and/or morality doesn't necessarily fit with the rest of the world's, the Batfamily being what it is.
Wolverine has had a number of unofficial "sidekicks" used to balance out his ferocity and vaguely thuggish appearance. The tendency of them being young girls in most media — Jubilee, Kitty Pryde, a younger version of Rogue — is almost a cliche, possibly lampshaded in his humorous short alliance with Power Pack's five-year-old Katie Power. And when Molly Hayes visited X-Men Headquarters, guess who ended up babysitting her?
Only it wasn't Pixie who ended up Wolverine's new sidekick, it was Armor, also a young girl.
Inverted in the case of X-23, whom he least tries to edge away from utter sociopathy and hoped to secure a more-or-less ordinary life for before Summers decided she would be a good addition to the covert wetwork squad he was putting together.
Oddly enough, X-23 often acts as a Morality Pet for Emma Frost. And has a Morality Pet of her own in the form of Hellion. And now she's acting as a morality pet for Gambit.
Subverted: Harley Quinn, the Joker's sidekick, is just as insane as he is.
Harley has her Hyenas too.
Of course, the easiest way of making the Joker look like a complete and utter bastard is for him to betray Harley. And of course, Harley does have a stopping point when the Joker gets too out of control. Her betrayal of him is much more forgiven than his betrayals of her (which tend to be very violent).
She has also acted as one to Poison Ivy. Whether or not Harley is around often determines whether Ivy is a Well-Intentioned Extremist serial killer (with occasional bouts of Complete Monster like the Harvest storyline), or merely Harley's snarky and more level-headed Cool Big Sis. No Man's Land also gave Ivy over a dozen morality pets in the form of a group of orphans she takes in and cares for in the quake ravaged city. When she surrenders to the police rather than let one of them die, even Batman admits that despite her claims to the contrary, Ivy is still a human being at heart.
In James Robinson's Starman, The Shade (already ret-conned from villain to just plain Anti-Hero) has a certain respect for Jack "Starman" Knight and falls in love with police officer Hope O'Dare. His true Morality Pet, though, is his home, Opal City; it is mainly because of his vow never to commit crimes in Opal City that he is able to make friends with the local law enforcement.
In the IDW Transformers comic, Sixshot is a war machine who doesn't think twice when instructed to wipe out entire civilizations, and was a prime candidate for membership with the planet-euthanizing Reapers. But there's nothing in this universe that would make him hurt his buddies/fan club the Terrorcons.
On a similar note Runamuck and Runabout are two thugs, basically only in the Decepticon army because they get to carry a gun and cause some damage. But if you hurt one in front of the other you're gonna be in trouble.
J. Jonah Jameson from Spider-Man is more of a cranky, cigar-chomping foil than a villain (these days), but Robbie Robertson acts pretty well as his conscience, and you can count on seeing his softer side whenever his astronaut son John shows up.
Todd "Squee" Casil is the involuntary morality pet of Johnny the Homicidal Maniac, who sneaks into his house for medical supplies and once saved Squee from a pedophile. While Squee is scared shitless of Johnny (calling him the "scary neighbor man"), Johnny tends to see himself as something of father figure to Squee, dispensing aesops because he doesn't want Squee to end up like he did.
In the Ranma, and other thingsFan FicHybrid Theory. Akane is a subversion of this. She and Chris think that his promise to her is keeping him from descending into true villain-hood, but it doesn't end up meaning much at all.
Adamska's love for Otacon and his alternate-future self's love for Big Boss in Stray.
Chewbacca is pretty much Han Solo's Morality Pet. If he weren't so good at guilting his buddy, the Star Wars trilogy would have been over after one movie.
In Repo! The Genetic Opera, Marni acted as this for Nathan. When she died, the role was fortunately taken over by Shilo, who in turn became Nathan's Morality Chain.
Mass murderer Riddick managed to find a few morality pets in Pitch Black, Fry, Jack, and Imam. Of course, Fry died at the end of Pitch Black, and Jack (Kyra) and Imam died at the end of The Chronicles of Riddick, leaving Riddick with no more morality pets, and a whole empire of necromongers at his command! Be afraid. Be very afraid.
Averted in Sweeney Todd: The Demon Barber of Fleet Street. Mrs. Lovett seems to have a soft spot for Toby and treats him as a son, while trying to keep him sheltered from her and the title character's business of murdering people and baking them into pies. Despite this, when he catches on to Sweeney's murdering ways (through his discovery of a purse belonging to Pirelli, his last master and Sweeney's very first victim, in Mrs. Lovett's possession), Mrs. Lovett's first instinct is to lock the poor kid into the basement where the pies are made preparatory to having Sweeney murder him. To top it all off she's also been feeding him human meat without him ever realizing it.
In Care BearsMovie II,Dark Heartmanipulates a girl named Christy into helping him, but develops affection for her after she saves him from drowning. After accidentally harming her, his remorse is enough to not only help save her, but also turn him human.
Literature
Inverted in Duumvirate. Luke is Paul's Immorality Pet, there to let him know that brutality, murder, and full-scale genocide are perfectly all right.
In the Dragonlance novels, the ambitious young wizard Raistlin Majere (who goes from Tall, Dark, and Snarky party member and Ensemble Darkhorse to full-on A God Am IBig Bad between series...) has an early Pet the Dog moment with the downtrodden gully-dwarf Bupu, whom he unfailingly treats with kindness despite the cruelty and ridicule her race is treated with on general principle. She becomes symbolic of his last ties to humanity and shows up several more times in his life, including a heartbreaking postmortem appearance in Raistlin's doomed, ash-choked future world.
In the Discworld novels by Terry Pratchett, Captain Carrot's first appearance (in Guards! Guards!) would almost count as being a Morality Pet for the Night Watch—he is everything they are not and, in many ways, are supposed to be. Even his naivete serves him well, in Ankh-Morpork of all cities.
Similarly, Lord Vetinari might be said to have a group of Morality Pets in the forms of his favorite catspaws: Vimes, von Lipwig, etc. A more literal Morality Pet might be the Patrician's since Making Money, late wire-hair terrier Wuffles, rumored to be the only living thing he cares for, and whose grave he still visits regularly. A more metaphorical Morality Pet might be the city itself, which he treats with care and even affection, striving to improve it, to expand its influence and power, to modernize it—but always, and most importantly, to keep it running.
However, note that neither the Night Watch nor Vetinari are "villains" per se. (Though Vetinari thinks he is a villian. But that's because, as we learn from his Hannibal Lecture in Guards! Guards!, he thinks everyone is a villain. In Vetinari's world, there are only evil people, but some of them are on different sides. And he's on the side of Ankh-Morpork.)
A version is Death's adopted daughter Ysabell which humanizes him, but subverted in that, while Death is shown as reasonable, in her first appearance in The Light Fantasic Ysabell is literally Ax Crazy.
Reversed with Death's granddaughter Susan. She was portrayed as rather cold in her first appearance, and it was arguably interacting with Death that humanized her (at the end she even allows herself to cry over her parents' death, something she had refused to do for years). Her subsequent appearances have had her working with children (as a governess and later a teacher), and these jobs seem to have increased her humanity further.
One of Forgotten Realms' old villains, the Zulkir of Enchantment Lauzoril was a Magnificent Bastard leading the Imperialist (pro-conquest) party of Thay. In The Simbul's Gift he turns out to be caring for his wife and particularly daughter, up to the point of taking an oath that his magic will never touch her, ever. 1
Dubious idea, but understandable considering what was done to his wife "for her own good" by her father. Lauzoril killed him, but could not undo damage.
On behalf of his daughter he eagerly breaks not only Thayan law, but rules he set for himself. And risks his life.
Artemis Entreri and Jarlaxle Baenre act as each other's morality pet, in a sense, as their friendship shows that they are capable of such. (It's especially intriguing when one considers Jarlaxle seems to be trying to reform Artemis.) Artemis also has a halfling friend in his home city, whom he respects and, to some degree, trusts. Note that Jarlaxle isn't actually evil: Artemis is less his Morality Pet and more his 'Look, he's capable of forming actual positive emotions right there in front of us' Pet.
The humble scholarship boy Redwing to the unscrupulous millionaire's son Vernon-Smith in the Greyfriars series. A slight variation in that while Redwing's steadying influence generally helps Smithy stay on the straight-and-narrow (well, roughly), when Smithy flat-out means to be bad, Redwing's intervention is met with a hypersensitive hostile backlash that can make things worse. Later in their friendship (for example, the Smedley series) Redwing learns not to waste a 'pi-jaw' on Smithy, and simply waits anxiously for the moment to beat some sense into him.
In The Vampire Tapestry by Suzy McKee Charnas, psychologist Floria Landauer functions as this for the vampire, Weyland, in that he reveals himself honestly to her, will not harm her, and even, for her sake, refrains from killing one of her clients who is harassing him.
Though, Brienne and maybe Arya, too, might qualify for Bad Ass, in their own right
In an interesting twist, Lucius, Narcissa and Draco Malfoy all seem to play this role for each other in Harry Potter, most particularly when Narcissa helps Harry fake his death, just so she can go back to Hogwarts and find Draco.
Lily could be said to fill this role for Snape, though that might be more of a Morality Chain. For that matter you could say Harry does too, though not even he realizes that.
In a weird, squicky case, one could argue Nagini serves this role for Voldemort. Granted, Nagini's evil too...but still, she seems to be the only creature he shows any true affection for, as messed up as that is.
Depending how you look at it, Voldemort is either Bellatrix's morality pet or a subversion, since her love for him only makes her moreAx Crazy.
Kreacher seems to have filled this role for Regulus (or, for that matter, Regulus' memory for Kreacher). Really the whole Black family, since Hermione speculates his secrecy was explicitly to protect them from Voldemort's wrath.
In Shakespeare's Titus Andronicus, the otherwise cosmically evil Aaron goes to great lengths to protect his baby son/morality pet.
In I, Claudius, Tiberius is portrayed as a pedophile who murders most of his relatives and a good chunk of the senate but for some reason he insists on having an innocent and virtuous senator live with him in his Evil Playboy Mansion on Capri. When the senator decides to commit suicide Tiberius is distraught, and actually goes so far as to tear up some death warrants in the hope that this will convince the senator to live on. (It doesn't work: the man wasn't committing suicide to protest Tiberius's crimes, but because he was tired of life.)
In one of the tie-in novels for Werewolf The Apocalypse, Well-Intentioned Extremist Arkady sets out to attack Malfeas, encounters a little girl who's held captive by Black Spiral Dancers, and spends some time first trying to get her out of the way and then trying to protect her as she follows him. She's Really 700 Years Old and a manifestation of the White Howler totem.
Subverted in The Death of the Vazir Mukhtar, where Griboyedov tries to help out ensign Vishnyakov, but ultimately fails (and what's more, the reason for it might be that his superiors, on whose decision Vishnyakov's fate depended, were somewhat antagonised beforehand by Griboyedov's aggressive lobbying of one of his projects), and Vishnyakov blames him for everything and commits suicide.
Lonely Werewolf Girl is one big book full of Black and Gray Morality. The darkest gray character of all is probably the most probably the title character, Kalix MacRinnalch. As of the second book, she's trying (Well, maybe trying isn't quite the word-being forced is more accurate) to go to remedial school. What's the only thing keeping her from quitting completely, in spite of all the werewolves trying to kill her, her anorexia and angstiness? Surprisingly enough, it's Vex (Short for Agrivex.) who keeps her from dropping out, admitting that she pretends college is fun to inspire Kalix.
Johnny for Dally in The Outsiders. When Johnny dies, Dally is so distraught that he essentially commits suicide.
In Dean Koontz' Frankenstein series, Mr. Lyss is humanized by the time he spends with Nummy, who he admits is the only person he's ever met that he doesn't hate. At the end he visits the grave of the grandmother who raised Nummy, whom Lyss had never met, and thanks her for the greatest gift he's ever received.
In Black Company series Darling seems to work as this for Raven, but as the time goes on it's clear that by focussing all that's good in him on her, he becomes even wrose for everybody else, up to the point of doing thigseven other members of Company finds despicableto protect her. Later Croaker start's suspecting that Lady wants to make him her own morality pet, to ensure she won't end up as Dominator and outright tells her how well it worked for Raven.
In the Time Scout series, Marcus is this for Skeeter, before his Heel Face Turn. Afterward, he's devoted to the downtimers in general, but Marcus and his family are special.
Live Action TV
On NCIS, Gibbs is cold to everybody and is all about tough love, except with Abby, whom he kisses on the cheek and gives hugs, massages and occasional roses, amongst other things.
And just to clarify for those who haven't seen the show, no, they're not screwing. It's more of a father/daughter relationship.
Dawn and Joyce fill the role for Spike in Buffy the Vampire Slayer. Spike values how they treat him. In particular, after Joyce dies, you can see that, as soulless bloodsuckers go, he's not all bad. After that, though, it was pure himification.
Dr. Cox and Jordan from Scrubs seem to have a morality pet in their son, Jack and their daughter, Jennifer Dylan. The main character, J.D. might also count as one.
In a strange way, Dr. Cox is something of a Morality Pet for J.D. Rather than in the traditional sense, J.D.'s interactions with his mentor sometimes force him to really think about whether he's more interested in playing by the rules or saving lives, and which is the "right" choice when the two diverge.
Subverted in Kamen Rider Ryuki: Axe CrazyOmnicidal Maniac Asakura Takeshi saves a little girl and protects her from monsters in an apparent Pet the Dog moment. It turns into a Kick the Dog when Asakura reveals that he cares nothing for her and was just using her as monster bait. Then back to a Pet the Dog when he ends up waiting outside her hospital bedroom to see if she gets better, even after she has no more use to him.
In the fourth episode of season 3 of Heroesa kid named Noah, who is apparently Sylar's son is the most distilled version of the Morality Pet ever seen for future!Sylar. He claims to have curbed his "hunger" for him. When he dies, Sylar explodes.
Heroes has quite a few: Nikki has a son that she throws herself into the action for to protect. More significantly, HRG has a surrogate daughter which leads him toward a straighter path than if he didn't have a daughter.
Heroes writers apparently believe Sylar is in desperate need of a Morality Pet. At the end of Season 4, Peter arguably applies, when he and Sylar are trapped together in the episode, 'the Wall', although it could be argued that Peter wasn't the impetus for Sylar's change of heart; Sylar's reformation was already underway. Too bad, but I think I see some Badass Decay in Sylar's future.
Whatever else Nathan Petrelli may be, you can't say he doesn't love his little brother.
Recent seasons of Doctor Who have suggested that the Doctor needs his companions to be this for him. After he loses Rose and Donna initially decides not to go with him, she tells him to find someone because sometimes he "needs someone to stop [him]" from going too far.
Michael's mother and to a lesser extent his brother in Burn Notice are his morality pets. His mother is a straight example. Nate is more complicated as he is useless and morally dubious but harmless and he frustrates Michael a lot. However the fact that he awakens Michael's Big Brother Instinct makes him this.
Michael's more pitiful clients tend to be this for Michael as well.
Michael is arguably Fiona'sMorality Pet. She would be a lot nastier without him.
Sue's sister, and Becky Jackson. It's kind played with with Becky, as Sue is about as abusive to Becky as she is to other students, which is kind of the point, a she has Down's Syndrome, and Sue treats her like any other girl her age, likely because of her sister
Beth, daughter of Quinn and Puck, though she's more Puck's morality pet.
Brittany, for Santana, showing that the latter is actually capable of a deep interpersonal relationship.
Rachel for Jesse. He's a dick to pretty much everyone except Rachel.
A meta example - Ryan Murphy's other shows (Nip/Tuck, American Horror Story) are intensely dark and disturbing. If you buy Glee's hopeful and optimistic message of inclusiveness as sincere, the show itself becomes this.
Several villains in Power Rangers have morality pets that show them capable of love and kindness and may even try (intentionally or not) to cause a Heel Face Turn, but the only one who actually succeeded was Nadira from Power Rangers Time Force, daughter of the Big Bad, Ransik. He showed during the series that he was willing to put his hatred aside for her happiness, and pulled a Heel Face Turn entirely when she jumped into the line of fire after twigging onto the Cycle of Revenge.
This is rather ironic as in the a season finale, Jeff ultimately chooses Annie as a representation of both change and being oneself in comparison to Britta and Slater. Quite literally, Annie was the best of both worlds for Jeff.
Daniel Jackson and to some extent the whole team for Jack O'Neill on Stargate SG-1. Daniel, enthusiastic, morally upright, slightly gullible civilian, seems to bring out the nobler side of the grouchy, hardened, ex-black ops O'Neill, who can be pretty ruthless when left to his own devices.
Though the stances were reversed on one occasion.
In Babylon 5, Vir is pretty much Londo's Morality Pet, especially in seasons 2 and 3 as he becomes more and more tainted by the Shadows.
Arguably, Effy was this for Tony in Skins, since his relationship with her was the only sign that he had any empathy at all during the first season. Although, Effy was much more than a Morality Pet and perfectly capable of carrying her own stories, so this example isn't one-dimensional as the trope description might suggest.
In Jericho season 2, Heather is a texbook example of that to Major Beck.
John Watson for Sherlock in Sherlock. Sherlock sees him as a friend; indeed, John is the only person Sherlock sees as a friend. John's presence humanizes Sherlock somewhat, forcing into question Sherlock's self-diagnosis of "high-functioning sociopath". When John's life is threatened in 'The Great Game', solving what Moriarty is up to becomes second to making sure John is all right. Moriarty even refers to John as Sherlock's "little pet".
Tora Ziyal is this to her Cardassian father, Gul Dukat during seasons 4, 5, and 6 of Star Trek: Deep Space Nine.
Though since Dukat goes insane after she is killed and eventually becomes the Bajoran antichrist, this could also be a Morality Chain.
Supernatural: Dean is this for Souless Sam in Season 6
The Shadow Line has Joseph Bede's Alzheimer's-afflicted wife. It makes it a lot easier to root for a wholesale cocaine dealer knowing that's he's only involved in One Last Job to pay for her treatment.
Rome has Eirene, Titus Pullo's vulnerable, doe-eyed slave and later love interest, whom he rescued. Unfortunately, Pullo's a Heroic Sociopath (though played for drama more than comedy) and his idea of expressing love for her is a little. . .warped.
Professional Wrestling
In WWE, long-running Evil Brit William Regal was assigned by Eric Bischoff to baby-sit and team with his "special" nephew Eugene, a mentally-challenged man who was, despite his handicap, a capable wrestler. Regal quickly grew fond of Eugene, to the point where Triple H's cold, cynical manipulation of Eugene served as a catalyst for a rare Heel Face Turn for Regal.
Jake "The Snake" Roberts, had Damien, his favorite of the many snakes he owns. Despite being otherwise portrayed as a Complete Monster, Jake was never shown as anything but kind to Damien. Sadly, after a Heel Face Turn, Damien suffered a (Kayfabe) death at the hands of John "Earthquake" Tenta. The feud against Tenta was Jake's last as a face (he shortly thereafter had a Face Heel Turn when he interrupted "Macho Man" Randy Savage's wedding and sicced a cobra on him), and in a bit of Fridge Brilliance, one can look to Damien's squashing as his Start of Darkness.
Tabletop Games
Archangel Dominic in In Nomine is often depicted as an insane Knight Templar. One person's rather popular fanon solution to this was to give him a kitten to soften his image. This more or less worked for a large portion of the fandom.
Horribly, horribly subverted in Children of the Night, a supplement for Vampire The Masquerade. In it is a character profile of Velya the Vivisectionist, who fell in love with a 10-year old girl and made her into a vampire. The source of his infatuation with her was her blatant sociopathy, and willingness to manipulate her family into insanity and murder. But that's not the worst part. Even though she was as evil as they came, Elaine Cassidy wasn't mentally equipped to handle vampiric life beside one of the most cold and calculating inhumans in the world, and quickly went batshit insane. Velya's response to his "wife's" degeneration was to graft her bodyintohis torso in order to keep her out of trouble until such time as he could find a cure.
In Magic: The Gathering, Xantcha serves as Urza's anchor to morality and to sanity.
The eponymous character in Verdi's opera Rigoletto will simply be a small-minded, vengeful court jester, if not for his daughter Gilda.
Video Games
In the H-GameIdols Galore, the protagonist would otherwise be a Jerk Ass at best, if it wasn't revealed that it's mostly a Jerkass Façade (albeit to hide his very reluctant good qualities). In fact, if he gets the ending with his Morality Pet, its revealed he's actually a fairly decent and even noble person who was hiding under several layers of asshole because he didn't want his inner decency to show.
In a city of twelve million people, there's only one person Alex Mercer gives a damn about: his sister, Dana. In fact, ultimately it turns out that the Blacklight Virus cares more about her than the real Alex Mercer ever did.
Arguably, Melissa Woodward, in Hotel Dusk: Room 215: Room 215. Main character Kyle Hyde normally looks, sounds, and acts like a washed-up Film Noir detective, but his actions with Melissa (including acting as her nanny, getting her out of a locked room 20 minutes later, giving her a stuffed rabbit doll, and getting an entire Christmas tree out of storage because she was complaining she didn't get anything for Christmas) prompts Hyde to note that he acts like "a sap".
The Crusader games don't really show how the Silencer reacts around his fellow Rebels, but the fact that he's apparently willing to stop by the bar and talk with them, or at least listen to them, makes for a nice contrast with his being a sociopathic killing machine.
In Betrayal At Krondor, whenever the dark elf Gorath does something that shows off his softer side, it usually involves his plucky young human companion Owyn.
Most Bioware games with romance plots give you Good, Paragon, Open Palm, or Light Side points for doing things that advance the romance. So, to play an evil character with a Love Interest, you have to turn back from the Dark Side at least a little bit, making Aribeth, Aarin, Ashley, Kaidan, Liara, Dawn Star, Sky, Carth, Bastila, and all the others all count as Morality Pets for the player.
This effect is noticeably absent in cases where the Love Interest is at least somewhat evil; see the Closed Fist option with Silk Fox and the dark-side option with Bastila.
In the later missions of StarCraft, Jim Raynor might be seen as the Morality Pet for Tassadar and the other Aiur-dwelling Protoss.
Matt Horner serves as one for Raynor in the sequel, stopping him from getting carried away.
Subverted in Baldur's Gate II: Irenicus tries to use his old lover as a Morality Pet, but since he's been exiled and stripped of emotional response (aside from thundering rages), every attempt he makes ends up being both misguided and just plain creepy.
In most single-player video- or computer-game RPGs, NPC party members aren't so much Morality Pet as they are Morality Compass - good characters will approve of good actions and deride evil ones, and vice-versa - but the fact that, for example, the option remains for the Player Character's old friend from childhood to still be treated like a favorite sister even after they've taken down a kidnapping ring and set themselves up in its place probably makes many players feel warm and fuzzy inside.
Averted in Black & White: the player's pet is a representation of the player and acts according to the player's desires. (Well, most of the time.) Of course, the player's desires can include eating pooping all over one's followers?
Raphael from the Soul Calibur series would seem more like a villain instead of an anti-hero if it wasn't for his foster daughter, Amy, being the driving motivation behind his actions.
Of course, these actions include trying to start a bloody civil war, and later trying to turn the entire world into vampires. This may be more an example of Love Makes You Evil.
Volgin's care for his lover, Raikov, in Metal Gear Solid 3. It's pretty much his only redeeming feature. The End also has his own Morality Pet, his pet parrot. If you shoot it, he will make a lot of noise about it. And heaven help you if you eat it...
Snake pours scorn on the very idea, and mocks Otacon for believing that liking dogs proves that Wolf is a good person.
In Fire Emblem: Sword of Flame, Nino is Jaffar's Morality Pet, changing him from a soulless Angel of Death to someone with actual feelings.
Lesser example, in Path of Radiance, the main character Ike is very much one for Soren, who has a tendency to be amoral and callous at the best of times. Played with in that Ike's the big, imposing one.
In No More Heroes, Travis owns a kitten called Jeane that you can feed and play around with. This has no gameplay purpose except to show that Travis isn't such a bad guy.
Final Fantasy VI: Shadow's devotion to his dog Interceptor is one of the chief things that humanizes him, despite the fact that the dog is a rabid killing machine that, according to his owner, feeds on strangers.
Although the "feeds on strangers" thing could be a lie. Oh, and Relm is this for Interceptor! (Although if you see all the dreams, then you know why, which also makes her one for Shadow!)
Kel'Thuzad, The Dragon to The Lich King has a little kitten within his Boss Room named Mr. Bigglesworth. If players kill it, he'll let out a Big "NO!" while swearing that his armies of undead will hunt you down. Officially, it's the last of his humanity. So it really is the closest thing he has to not being pure evil.
Final Fantasy VII's Barret Wallace has a daughter named Marlene to remind the audience that there's a soft heart beneath his perpetually angry exterior.
In the sequel spinoff, Dirge of Cerberus, Vincent Valentine has both Yuffie Kisagari and Shelke.
In Gungrave, player character Grave's young protectee Mika is one the few things that keeps him from being a completely mindless killer, as she is a memento of the people he held near and dear when he was still Brandon Heat. She is something he can "live" for, the one good thing left in his "life".
Tsugumi of Ever17 was probably coming off a little too strong on the jerkass and a little weak on the broken bird. Plus they needed a way to suddenly make her get along better with Takeshi, so they introduced Chami the Djungarian Hamster. He's named Chami because he's charming.
In Quest for Glory: Shadows of DarknessTanya fills this role towards Katrina, who wants to resurrect the local Eldritch Abomination. Boy, do you feel like a jerk when do the right thing by returning Tanya to her rightful parents. Fortunately for you, by the time this happens in the game, you've become Katrina's new morality pet, even though she doesn't realize it until it's too late.
Harvest Moon DS has Daryl, the creepy Mad Scientist living in the southern part of the valley. In previous games, he was known for wanting to experiment on your cows and accusingly discussed the effects of methane produced by cows on global warming. In this game, he stalks archaeologist Flora. However, if you decide that you actually want to befriend him... You discover that he rescued an injured mermaid girl named Leia after she washed up on the beach, and has been diligently caring for her ever since. She's so grateful to him, she helps him cook, and despite her being an anomaly of science, he never once experiments on her. In fact, when she's all better, he sets her free into the ocean, and she's forever grateful.
The Magypsies in Mother 3 all have pets to show their caring side, but Locria's pet mouse is the best example, being the only hint that he wasn't totally evil.
Fanon, being fanon, likes to make Adrian Andrews into a Morality Pet for Franziska Von Karma. In the actual games, she does latch onto Von Karma because of her dependency issues, but the main reason Von Karma is any nicer to Andrews than she is to anyone else is that at this point in continuity, she's still dedicated to her win records and knows that this is the best way to get Andrews to work with her in court. Later on, when Von Karma is less of a royal bitch and doesn't need a Morality Pet so much, Andrews is learning to stand on her own, without the aid of the strong mentor figures she relied on.
To some extent Trucy acts as a sort of Morality Pet for Phoenix after he is disbarred, and as we see that he becomes totally Bad Ass after being disbarred, if he hadn't had a Morality Pet...
In Pokémon Colosseum, ex-Team Snagem member Wes (also the main character) has Rui. He actually decided to flatten the first evil gang in the game before meeting her, having apparently decided that he just didn't like them anymore, but didn't decide to actually help save Orre until she showed up.
In the main game of the Generation III and IV there is a subtle example. The criminal leaders of Team Aqua, Team Magma, and Team Galactic (Archie, Maxie, and Cyrus respectively) had a Golbat the first time you fight them. In the later times, they have a Crobat', a Pokemon which needs maximum happiness of Golbat to get.
Even Kratos of God of War has one in his daughter Calliope. While for the most part a Heroic Sociopath who's always just barely avoiding slipping into Complete Monster territory, invoking his Papa Wolf nature can lead him into acts of heroism and selflessness, as seen in Chains of Olympus, where he gives up the chance to remain with his beloved daughter in the Elysium Fields in order to save her and the world, including a button-mashing sequence where he must push her away.
In the third game, he gains another one in the form of Pandora.
One of the more shocking twists in Ghost Trick is that Big Bad Yomiel had one of these...and it's the main character. Sissel's Ghost Amnesia made him forget that he was a stray cat who became Yomiel's sole companion during ten years of undead isolation from humanity.
Theresia: Dear Emile subverts this quite brutally. Emile killed Leanne's mother when the latter was an infant, but kept her alive and raised her in an attempt to understand the concept of love. Seeming more obsessed than truly maternal, she kept the child isolated from all other people, and sometimes kept her in chains. She never showed any love or affection towards her, but Leanne loved her anyway and considered her a mother figure, growing to love the smell of blood and the sound of screaming as reminders of her. Ultimately, Emile protects Leanne from the other soldiers, but tries to kill her herself rather than let her escape to the outside world.
Taro acts as one to Rozalin in Disgaea 2: Cursed Memories, and Etna's a lot nicer to Hanako then she is to the rest of the party.
Raspberyl to Mao in the third game. Becomes a Morality Chain in the bad ending.
Dragon Quest IX plays with this in Coffinwell: Doctor Phlegming is very antisocial, and his cheerful wife Catarrhina appears to be the only other person he cares about... yet he still neglects her in favor of his research. In fact, it's actually her death that spurs him to change his ways for the better, effectively Inverting the usual trope.
Portal 2 gives us Cave Johnson, the CEO of Aperture Science and his assistant Caroline. Cave may have been hilariously insane and disregarding of his employees' safeties, but he had lots of respect for his assistant, who were one of the few people who could restrain him when he lost his temper. While he eventually forced her to be uploaded unto GLaDOS later on against her will, it is still obvious he still has some ounce of respect for her, in that he does it not out of maliciousness, but due to wanting her to run the facility after his death due to his high regards of her.
Valve pulls this again in Team Fortress 2, giving The Medic a group of doves as pets in his "Meet The Medic" short. His favorite, Archimedes, appears to be just as morbid as he is, however...when things explode, he leans in to watch, often getting covered in blood, and he has a disturbing habit of nesting in patients' open chest cavities.
In World of Warcraft, Anduin Wrynn is this to his father, Varian Wrynn.
Web Comics
Built in to troll psychology/romance on a fundamental level in Homestuck. MOIRALLEGIANCE pairs are basically this trope, where a calmer troll keeps a more hot-tempered or violent troll's dangerous tendencies in check and they balance and complement each other's personalities. Three examples exist at the beginning of the troll arc: Kanaya for Vriska, Feferi for Eridan, and Nepeta for Equius. Subverted in that Vriska is still a HUGE BITCH BLUH BLUH even with Kanaya's help, and Feferi broke up with Eridan early on. Nepeta plays it straight except for the fact that on closer examination Equius might not have been that bad a person without her anyways. (He says he might have been.)
The Equius <> Nepeta dynamic is also interesting as Equius believes that he is the one protecting Nepeta; later on, he admits conversely that without Nepeta's support he believes he would probably be violently unstable.
More recently John seems to be becoming one for Vriska.
Kanaya also finds herself accidentally slipping into this role for Rose, but when Rose mentions it she tries to backpedal because she doesn't want a repeat of her relationship with Vriska.
As of late, Feferi dumping Eridan has had bad consequences for the team. On the flipside, Karkat became one of these for the psychoticGamzee, successfully ending his murder spree without any further bloodshed.
And at the end of Act 5, Karkat becomes one for Gamzee, finally quelling his murderous rage, which had been going for half the act.
Subverted in Furmentation - Alexi goes into a violent, psychopathic rage when his teddy bear is stolen, but having it doesn't seem to make him any nicer than usual.
While he's antisocial rather than villainous, Davan Macintire and his relationship with Rory fit this trope. He's still grouchy and sarcastic around Rory, but he seems to give more of a damn about the kid than he does about most people even upon learning that Rory isn't actually his son.
Mr. Scruffy in Order of the Stick, who is probably the only living thing Belkar genuinely likes and cares for besides himself. Mr. Scruffy doesn't seem to make a dent in Belkar's morality (or lack thereof) otherwise, though. In fact, Belkar seems to like Mr. Scruffy largely because the cat appears to be as much a vicious little bastard as Belkar himself (though he partially does it in honour of Shojo).
On the other hand, Belkar interprets such things as eating meat and batting at a piece of string as "vicious." ("Kick that string's ass.") He's inclined to see normal cat behavior as vicious and bloodthirsty; perhaps an unreliable interpretation of the cat's character.
That said, Mr. Scruffy also actively took part in Belkar's fight with the Thief's Guild, and a recent strip has him bat a bowl of maggots on a bunch of people to apparently escalate a bar fight...
Mr. Scruffy plays the role a little bit straighter here...
Played much straighter with Blackwing to Vaarsuvius in the most recent arc. Vaarsuvius isn't so much evil as (possibly) True Neutral, but sie has anger problems.
While technically human, Piffany from Nodwick is the only reason Artax and Yeager actually display any kind of heroism ever. There's a reason A World Without Piffany is so crapsacky it makes even the normal Nodwick world seem pleasant.
Buck Godot has the Beemahs become this for the Klegdixal, starting in this comic.
Prior to, and unbeknownst to anyone else, the Beemahs were sort of the Morality Pet the Klegs wished they had-the meeting between the Beemah and the Kleg ambassador is kind of a Crowning Moment of Heartwarming, as the usually rude and self-serving Klegdixal pours his heart out with gratitude to Buck for reuniting the two species, as the Klegs had apparently been the original creators of the Beemahs and their one selfless urge as a species was to fix all the things that had gone wrong in the process (many of them flaws which are used to exploit the Beemahs by another party).
Another side of it approaches Morality Chain, as all known Alternate Universe variants of Tedd got a good friend Elliot and at least once the female counterpart Ellen is his girlfriend; the only exclusion is Lord Tedd's world — and instead of Grace there's a big ill-mannered Blood Knight.
Played with early in Sluggy Freelance, when Kiki the ferret's regular Catch Phrase was "Stay good, Riff! Stay good!" Otherwise averted; Torg's Immorality Pet doesn't seem to have changed him, and Bun-Bun's Alternate Reality Good Version didn't stop Torg from sliding into embittered self-interest in the Dimension of Lame.
Danya, Survival Of The Fittest'sBig Bad, is occasionally revealed to take time off from his commitments running the Act (including making the announcements) and going home to see his family. The obvious love and affection he has for his wife, young daughter and grown-up son serve to humanise him somewhat. Most members, however, still loathe him.
They also fully support his activities, giving him even more motivation to act like a monster.
In GargoylesMagnificent Bastard David Xanatos has a infant son named Alex in the second season. The Gargoyles helping protect the baby from his god-like grandparents (long story) encourages Xanatos to rethink his priorities.
Also, to some extent, his then-fiancee Fox, almost literally when she temporarily becomes a furry.
To a certain degree, Demona's daughter Angela. On any other occasion, Demona is still her usual self.
In Ben 10 Alien Force, the main reason Kevin decides to do anything good is because he has developed a crush on Gwen.
There's also Cash and JT: at the end of the episode, JT talks Cash out of letting the robot hand take over his body and fighting with Ben.
In the Samurai Jack episode "Tale of X9", the robot hitman X9, the only one of his model with free will and a processor about him, abandons his job after finding an adorable abandoned puppy, Lulu. As far as he was concerned, all he needed was her... which is why he was forced back to work when Aku kidnapped her. In a bit of a Tear Jerker, Jack cuts him down like any inconsequential enemy. X9 asks him to take care of Lulu, then dies.
In Treasure Planet, Long John Silver has a literal Morality Pet called Morph, a cute bloblike alien that apparently represents his conscience. One could argue Jim Hawkins himself is another Morality Pet for Silver.
On Total Drama Island,Duncan is a Jerk Ass to other characters most of the time, but finds his Morality Pet in Gwen and it's stayed that way for three seasons straight. He also is pretty good friends with Owen.
Subverted in the Justice League episode featuring the Justice Lords. Flash is pretty sure that the Mirror Universe Superman (who's gone a bit totalitarian nuts) won't be able to kill him because of what the Flash represented to that group. Reverse!Superman is quite prepared to heat-vision his brains out, however. His own universe's Superman admits that he knew even Flash wouldn't be able to talk Reverse!Superman out of it.
Flash: Can't do it, can you? I'm the last bit of your conscience. This is the one thing you'll never do.
Superman: I've done a lot of things I thought I'd never do these part two years. One more won't hurt.
He tends to still play the Morality Pet role for his own universe's League, however. Sometimes to extremes and lampshading.
Don't forget about the Green Arrow. The Justice League brings him on to the team for the explicit purpose of being the Morality Pet.
Actually, they didn't bring him on to be so much a Morality Pet as they knew that GA would be the first person in the world to accuse the League of going to far. He's more of the conscience.
Jimmy Two-Shoes is this to Heloise since she's in love with him, but not even he's safe from her anger and wrath.
Without Jane Lane, the titular character of Daria would be, well, unpleasant to be around.
Also, as seen in the episode where Jane joins the Track team. Daria begins to obviously go mad, voicing her ENTIRE internal monologue.
Not that Sully was in any way villainous before he met her, but her reaction to him roaring does clue him in on how traumatic his job can be for the kids he scares.
