Used to Be a Sweet Kid





""The boy that you loved is the Man that You Fear...""

- Marilyn Manson, "Man That You Fear"

Used to Be a Sweet Kid applies when a villain or other dark and troubled/troubling character was not so as a child: the trope name also tends to appear as a Stock Phrase in these cases. Works, and audiences, may vary considerably as to what point they consider a character to be past the adolescent stage here, but post-adolescents in general need not apply.

Aversions will usually be notable here, given expectations that Children Are Innocent, or that there's at least some Ambiguous Innocence even when Kids Are Cruel, so people will tend to assume a Start of Darkness must have happened, and that there will be a Freudian Excuse that will explain (if not excuse) all. By extension, this trope frequently applies through subversion, inversion etc. where an Enfant Terrible, Creepy Child, or Axe Crazy junior initially manages to get past everyone's radar but is actually a little horror from the start. ("And he seemed like such a nice kid"). Often, it is not clear which a character fits under, which in turn often leads to a Flame War, especially if the character is also a Draco in Leather Pants.

Generally, the trope tends to be reserved for villains near the Big Bad end of the villain spectrum, but can also be played for What Measure Is a Mook?. Also, while this is most commonly a villain trope, it can apply to characters who are not so much aligned with evil as troubled, bitter and twisted, cynical, jerky, despairing, lacking in emotions or differently sane. Or an Anti-Hero. Or just going through puberty. (In the latter case, expect the parents to invoke the trope name.)

When played straight, this trope tends towards Rousseau Was Right, though if other villains and darksiders in the same work do not fall under the Used to Be a Sweet Kid trope, Rousseau may have only a partial victory, and the trope is sometimes used as the exception that proves the rule in Hobbes Was Right or Humans Are Bastards scenarios. Also frequently used, straight or otherwise, to make more or less Anvilicious points about free will, destiny, individual responsibility, or the moral version of Failure Is the Only Option.

Handled well, this trope can really add depth and complexity: handled badly, especially by combination with a poorly executed Freudian Excuse, it tends to cause Badass Decay and Villain Decay.

Often related to From Nobody to Nightmare, though the character may be of some prominence from an early age, or even from birth. This subset of the trope can be heart-breaking, as when a long-awaited Chosen One turns bad. Also often the precursor to Break the Cutie and Woobie, Destroyer of Worlds. In these cases, expect it to be Played for Drama with extra Tear Jerker moments. It's also often invoked to make the audience Cry for the Devil.

Sometimes, the "used to be nice" stage may be revealed only retrospectively, often by a third party, and the villain himself/herself may treat the "sweet kid" stage as an Old Shame that undermines their Villain Cred. This last one may be Played for Laughs, as the villain furiously denies their Pet the Dog past, often complete with stomping on cutesy childhood toys and memorabilia. Or it may be Played for Drama in an "I Know You're in There Somewhere" Fight with the good guys. If the author (s) really want to put you through the wringer, they'll apply this trope to a Complete Monster.

Compare to She's All Grown Up, in which the character may have been a sweet kid, but is now a very attractive woman.

No Real Life Examples, Please

Anime and Manga
" Yuno: When did I become so twisted?"
 * Black Butler
 * Pictured above: Ciel Phantomhive. He's a cynical, callous, and very driven 12-year-old (or 13, depending on how far you are in the series), is a Chessmaster and Wise Beyond His Years. He has no qualms about getting involved in dangerous missions and will command his Badass butler Sebastian to kill someone without a second thought. He has also been shown slapping and insulting individuals for being too comfortable with touching or speaking to him. The only individual he appears to genuinely care for is his fiance, Elizabeth Middleford, although he does seem to view her as a bit of a distraction and a nuisance, at times. In the anime, he appears downright cruel at times, although in the manga, he is simply just icy and elitist. It's eventually revealed that he was a happy, loving, carefree child before his tenth birthday. Then his parents were murdered, the mansion set on fire, and he was kidnapped. He was locked in a cage with other children his age and eventually was to be a child sacrifice until he accidentally called upon a demon in his desperation to live.
 * Alois Trancy in the second season. He was shown to be cute and innocent as a child but then his foster family died in front of him, from unknown supernatural means, including his adoptive brother and only friend, and then he  A few years later he's shown to be creepily Ax Crazy.
 * JoJo's Bizarre Adventure
 * Jotaro Kujo. First we see him in past as an little boy playing with mom and as an model student, and on the next page he's in a cell, terrorizing fellow prisoners and telling his mother to shut up.
 * Subverted later on in the manga when Alessi uses his stand to de-age Jotaro to about seven years, and Jotaro was still capable of pounding Alessi pretty seriously, and still had his not-accepting-any-nonsense mentality which, given the way Alessi's stand works (its victims don't remember anything from the years they lose), Jotaro must have had even then.
 * from Monster, is retrospectively revealed to have been a sweet kid . Then the Orphanage of Fear really got to him - and as for the later character he shows in the story proper, let's just say "wouldn't hurt a fly" is not the phrase that leaps to mind.
 * Johan Liebert, the series' Big Bad, is about as mind-bending a deconstruction of this trope as he is of Complete Monster. For which he is the poster boy.
 * Peter Capek is another example. Once an ordinary kid, now a Mind Rape-inflicting fiend.
 * Even played with with Peter Capek, as
 * Michio Yuki from Osamu Tezuka's MW is a sweet-natured, rather shy kid till the age of nine when he gets, in short order, taken hostage,, and exposed to potentially lethal neurotoxins that fuck up his mind terribly. After that, he goes "a bit" off the rails.
 * Osamu Tezuka loved this trope. Most incarnations of Rock have a similar story. Perhaps the most heartbreaking example is Adolf Kaufman, one of the three title characters of Adolf. As a child he befriends a young jewish boy and resists his Nazi father's hateful ways, but he's soon shipped off to a Nazi training school and it all goes downhill from there...
 * In Full Metal Panic!, one side story focusing on Sousuke and Kalinin's backstory showed that Sousuke was this. During his childhood, when he was rescued by Kalinin and they spent time together, Kalinin was shown to love Sousuke and grow so attached to "that sweet and gentle boy" to the point where he really wanted to adopt him as his own. Then they got separated, and the next time they meet, they met as enemies, with Sousuke becoming the Nietzsche Wannabe Stoic that we know today.
 * Naruto has done this repeatedly with major characters.
 * Gaara, despite his great power, just wanted to have friends. However, after one horror too many, he snapped and became an Ax Crazy Dark Magical Boy with Omnicidal Maniac tendencies. He got better after the main character beat some sense back into him again.
 * Sasuke used to be a genuinely likable, out-going child. Then Itachi broke his mind repeatedly and other shit happened. He is currently The Dragon of the Big Bad, and things won't get any better anytime soon.
 * As a child, Nagato looked like he could be The Messiah. Then...things hit the fan, he renamed himself "Pain" and decided it was better to be a Dark Messiah.
 * Don't forget Orochimaru. He was one of the Legendary Sannin, and he showed great promise as the next Hokage. He was a kind and helpful orphan, but then he got the idea that he could either bring his dead parents back or extend his own lifespan enough to meet them again when they got reincarnated, if he got more powerful. And he started doing questionable experiments, and becoming a Complete Monster, to the point of literally becoming a demon.
 * Itachi himself was an adorable boy who genuinely loved his brother and his village. After shit hits the fan, he seems like the biggest Jerkass in history, until we find out why he is how he is. He had watched countless people die in a bloody world war, and it gets worse after that.
 * What about Sasori? LOOK at this boy!. His parents died when he was very young and his grandmother kept lying to him that they were away on a mission. He grew so alone from the lack of love from his mother and father that—when Chiyo taught him the art of puppets—his first two creations were that of his Mom and Dad. But they could never replace the kindness, love, and affection that human parents could provide, which lead to the development of his twisted views on immortality, the sanctity of life, and how it was so fleeting and needed to be preserved... Cold, emotionless, stoic, and impatient with wasting time. Gee, thanks Sand Village!
 * Konan. She used to be a sweet little girl, then things happened.
 * And as of chapter 582, if his flashback is to be believed,
 * Teru Mikami of Death Note was a really sweet kid who would always defend the weak and was a Bully Hunter. As he got older, the fact that most people seemed to tolerate bullying gave him an intense sense of Black and White Morality which was strengthened when some of his bullies ended up being killed in an accident. Once he got his hands on the titular Artifact of Doom, he ended up as the craziest person in a series filled with some fairly unstable people.
 * To a degree, also Misa Amane. Had her parents not been killed by a burglar when she was a little girl, she would've possibly grown into the same beautiful and popular Idol Singer she was in canon... but without the Ax Crazy Yandereness.
 * Light. Nice, normal family, top of his class, popular with other students... and he's killed God knows how many people by the end of the second episode.
 * Light and Misa were distinctly never normal; they have emotional impairments of some kind. It's possible Misa developed her psychopathic tendencies somewhere between her parents' deaths and meeting Rem, given she's had actual trauma and a showbiz career to mess with her head, but Light is pretty...empty.
 * Or not—the fact that he dropped tennis because it was pointless and several other moments indicate that, even if he was always broken inside, it had been getting worse before he found the titular Artifact of Doom.
 * When Light, he returns to being a nice, morally sound person. In other words, he was just a REALLY bad case of With Great Power Comes Great Insanity.
 * Lucy from Elfen Lied, who started out as a kind-hearted but shy little girl, but through enough torment, crippling loneliness, and a psychotic inner voice became an Ax Crazy mass murderer bent on killing all humans.
 * Simply one person: Doctor Jizabel. If you've read Godchild, you know he's a perfect example.
 * Lampshaded in Lucky Star, when Konata and Kagami talk about how when criminals are arrested in real life and people who knew them are interviewed, they will always say things to the effect of, "he wasn't a bad kid." Kagami then says that if Konata ever gets caught, she'll tell the media that she had "always figured she'd do something like that".
 * Most of the Egrigori experimental children were like this, before whatever processes they were put through were completed. The Keiths mostly became bloodthirsty psychopaths who had no problem killing anyone they had to and . The fact that the kids were treated terribly and given almost no positive human contact could explain a lot
 * Mao from Code Geass was a sweet, innocent little boy until . After  it ultimately broke him completely and drove him insane, so he turned into a Psychopathic Manchild with no grip on reality who Mind Rapes the local Messiah and the Knight in Shining Armor and kidnaps the Ill Girl... To say that his opponent, the Ill Girl's Dark Messiah, was pissed off at him, is an understatement.
 * This is a prominent theme in Code Geass, while some characters like Rolo are proven to always have been killing machines since childhood (and often, like in Rolo's case, thanks to the brutal training and brainwashing coming from the ), loads of characters started out like sweet kids even up to the Emperor but also including, C.C., Suzaku, possibly Cornelia and Clovis, Karen and Lelouch Lamperouge.
 * Lucia, from Rave Master. He goes from being a sweet little 6 year old who hids behind his mom when he sees a stranger to being a psycho-killer at the age of 16. He's somewhat forgiven for that because he spent the ten year gap between those two points locked in prison for no good reason after having to watch his mother get shot down.
 * Fist of the North Star: There was a little boy who loved his adoptive father, a martial arts master. Then his father decided to take in some students and teach them his art. The boy felt left out, especially when his father refused to teach him. The boy pushed and begged until his father decided to teach him as well... and that little boy grew up to be Jagi. The story doesn't have a happy ending.
 * There was a tiny baby, abandoned by his parents and adopted by another martial arts master. Though trials were difficult, and the regiment strict, never once did the little boy feel that it was a burden, being driven by nothing more than his love for his adoptive father. Then came the time, when he became 15, to inherit his master's style after a final trial and become and adult. The little boy's name was, and neither does this story have a happy ending. Well, almost had.
 * There also was a young boy, left orphaned with his younger brother, who knew that crying will not make things better, and instead aspired to become stronger along with his brother. As the two get adopted by a martial arts master, the two finally learn to become stronger and this young child aspires to greater glory in his quest for strength. This boy grew up to be, but his story does have a happier ending.
 * Axis Powers Hetalia brings us resident Psychopathic Manchild Russia, who was just adorable and sane (and oh-so-woobie) as a child. Then came this and this, and I don't think this did him any favors.
 * There's also his sister, resident Yandere Belarus. We see her in her, Russia's and Ukraine's backstory as a cute little girl who clings to her brother and pouts to her older sister. And then, we see her now, as a scary Strange Girl in a frilly Elegant Gothic Lolita dress...
 * America from England's perspective, who used to be a sweet Cute Shotaro Boy and just adored England. Then, we all know what happened next.
 * England too, apparently. The youngest we've seen him was in the Passing Through The Year 1000 strip, when he happily agreed to let France pretend to have conquered him. From there he became a very unhappy child, then a "juvenile delinquent" who's hobby was piracy, and eventually settling into the Jerkass Tsundere we all know now.
 * Clair Leonelli of Heat Guy J. He used to be a cute chibi with a very demure personality. After years of abuse from his dad, he eventually went insane,, and became Daisuke Aurora's puppy-kicking arch-nemesis.
 * The main character Jae Hyuk of the manwha Immortal Regis started out as a sweet Ordinary High School Student devoted to caring for his Ill Boy little brother. Then both of them got dragged into another dimension full of swords and sorcery and monsters. Jae Hyuk is forced into the role of The Hero while his little brother . Over the course of the series Jae Hyuk becomes more and more jaded and bitter about having his old life ripped away from him (being turned into an undead abomination didn't help either). In the sequel series Cavalier of the Abyss which takes place years later, Jae Hyuk has become the new king of the other world. The first thing we see him do is ruthlessly order The Purge of a village of suspected rebels—men, women, and children alike are all put to the sword. He also chops off the arm of a soldier who questioned his orders. He's not so sweet anymore.
 * Bleach:
 * Karin Kurosaki. Also, her brother Ichigo, and said brother's rival Ishida. Both were adorable as little kids but it got considerably worse for both of them after their break the cutie events (Granted, Ishida was already pretty unhappy before his Break The Cutie event, but still).
 * Gin is the poster child for this. Yes, that Gin. To the point that some call him Moe. Note that he was presumably never mentally stable and became an Ax Crazy killer while still a child.
 * It's easy to forget because her personality does a 180 immediately after the flashback revealing this, but Sui Feng. The very cute and shy teenager who bordered on Yamato Nadeshiko when off-duty, very easily blushed at the sight of her "Princess" Yoruichi, and wanted to protect her? Yeah, she's the same hard-ass and once borderline sadistic Action Girl from Squad 2.
 * Miharu Rokujou from Nabari no Ou.
 * Adam Blade from NEEDLESS, who is, to put it mildly, a violent Lolicon Anti-Hero. Even his foster-father wonders just what the hell had gone wrong in the process.
 * Chouji Suitengu, back then known as from Speed Grapher was a pretty sweet kid, who loved playing games with his little sister. Then his parents were murdered for not being able to pay their debt to the Roppongi Club. Suitengu was sold off as a child soldier, almost killed during his final mission, and then turned into a Frankenstein stitch job. Nowadays, he's a textbook example of Four Eyes, Zero Soul.
 * Yuno Gasai from Mirai Nikki wasn't always such an psycho girl. When  It turns out that despite her abuse, she still was hopeful and idealistic.
 * Yuno Gasai from Mirai Nikki wasn't always such an psycho girl. When  It turns out that despite her abuse, she still was hopeful and idealistic.

"Knives: There's no difference between people's hearts and ours, so if we try, I'm sure everyone can understand each other."
 * Balalaika from Black Lagoon used to be a pretty, young and seemingly friendly girl, whose dream was to do her family proud in the Olympics as a sharpshooter. That is...until the Afghanistan War.
 * Surprisingly, Guts from Berserk was actually a sweet and innocent kid. The downfall started when he was three and his foster mother Sys died of the plague, leaving him to be raised by his sadistic and hateful foster father Gambino. Even after being trained for war and serving on the front lines, he was still a pretty innocent kid, until the night after his first battle when Gambino
 * Millions Knives, the Big Bad of Trigun. Anime him...kinda, but the psycho tendencies were there even before he flipped out and became a full-blown Creepy Child. Manga Knives...had something much better to flip out over, and before that, just listen to the kid.


 * This attitude did not survive contact with For Science!! Look at your big sister's preserved vivisected corpse, and the records of how the only people you've ever known experimented her to death before she was a year old! See the lovely metastasized cancers from all the scans!
 * It's obvious Vash was a cute kid, but flashbacks reveal Wolfwood was as well...more recently than you might think. And Livio, despite already being psychotic at the time, too.
 * Actually, The Reveal with Vash is that he briefly cracked up and believed Humans Are Bastards and displayed a really creepy suicidal laugh, after the Tessla thing. He just pulled himself back together for Rem after accidentally stabbing her, and has somehow soldiered on ever since.
 * Manga Legato gets a dubious entry, because while there is nothing innocent about his flashback (he was a kept catamite who was discovered in a plan to kill everyone he'd ever known and was therefore being raped to death when Knives turned up and coincidentally sliced up everyone but him, because he subconsciously used his psychic powers in self-defense), it's practically impossible not to get choked up at the look on his face when he realizes Knives is going to allow him to live and follow, and he admits he has no name.
 * Ken Ichijouji from Digimon Adventure 02. He got better.
 * This trope tends to recur throughout the manga adaptations of Digimon. Digimon V-Tamer 01 had Neo Saiba, and Digimon Next had Shou Kahara.
 * Kiriha Aonuma from Digimon Xros Wars is shown to be gentle as a child in his back story. His father
 * The first line in the Baccano! novel set in 1705 is from Huey Laforet's mother, talking about how innocent he was. A couple of hundred years since, he's become a Mad Scientist who sees all humans (including his own children) as "raw materials."
 * Sakurako  from Sakura Gari was a sweet and adorable child, right until she witnessed the death of her mother under some very screwed up circumstances  . She then became a seriously Creepy Child,
 * While the primary casts of Puella Magi Madoka Magica are kids by most definition, Sakura Kyouko used to be a sweet, good Japanese Christian girl who only wanted to help her father in spreading the word of his God. No wonder she's such a misanthropic Jerkass. Also, Homura  warped her into a cold, lonely Anti-Hero.
 * of Cowboy Bebop actually used to be a very sweet idealistic child from what could be told from the lost tape found from a time capsule. It is a very sad comparison to how is grown up.
 * A Pokémon manga called How I Became a Pokémon Card has a chapter on a boy. He's a sweet boy who takes in an injured Persian who ran away from a group that keeps "precious" Pokemon to stare at all day. Who's this boy? The infamous Yakuza boss, Giovanni.
 * Trip from Pokémon Best Wishes shows HUGE signs of this. The only flashback the audience has of him is when he meets the Champion, Alder. Back then, he was an adorable, hyperactive kid that wanted to become a Pokemon Trainer so he could battle the Champion one day. Fast forward into the present time when Ash first meets him. He's a trainer now, but the happy go lucky personality is gone. Something happened in that time period to make him change so drastically.
 * Enchu of Muhyo and Roji's Bureau of Supernatural Investigation used to be quite nice and hard-working in comparison to Muhyo, and especially cared for his sick mother, hoping to become an Executor and support her. Losing his mother to her illness and his chance at getting the position resulted in him turning evil..
 * Deadman Wonderland:
 * Before the earthquake, Minatsuki Takami aka Hummingbird appeared to be a sweet adorable child. Then after her mother grabbed a pot of flowers and left her to die, her more sadistic tendencies began to arise.
 * Also applies to  of all people, when it revealed that he was once a kind forgiving buddhist priest who was constantly bullied and beaten and once fed an injured cat. It was until the earthquake that he lost his sanity.
 * Barnaby Brooks, Jr. from Tiger and Bunny was a joyous, trusting child constantly showered with love and care courtesy of his very affectionate parents. But resulting in Barnaby becoming cold, cynical, consumed by the desire for revenge and reluctant to trust anyone; up to the point where he has avoided close relationships with other people for 20 years. Subverted towards endgame in that he regains traces of his original personality upon befriending the show's Idiot Hero, Kotetsu.
 * Alviss of Marchen Awakens Romance.
 * Gundam:
 * Gundam SEED: Compare the Athrun in the flashbacks, who believed that Earth and ZAFT would never go to war, with the bitter, cynical soldier we all know and love. Also, it seems that the entire universe is bent on turning main character Kira into one of these. He gets it back mostly.
 * Gundam SEED Destiny: Shinn Asuka was a nice kid who loved his family, and especially his little sister. Then they all died. In front of him. Goodbye Cheerful Child, hello Berserker. His friend Rey Za Burrell is also an example; flashbacks show him as a Cute Shotaro Boy with a love of the piano, and nothing like the Utopia Justifies the Means Well-Intentioned Extremist and Manipulative Bastard he is today.
 * See the sweet-looking pre-teen girl in this illustration? That's Haman Kahn of Zeta Gundam and Gundam ZZ. Yes, THAT Haman Kahn.
 * Raven/Gilbert Nightray of Pandora Hearts was absolutely adorable as a child. Following his Break the Cutie event he became a brooding, serious man with major issues. Oz could count too.
 * Tetsunosuke and Suzu of Peacemaker Kurogane.
 * Litchi Hikari Club: Tamiya at the very least, and he still is to an extent.
 * Shinji and Asuka from Neon Genesis Evangelion, and practically the entire cast. Rei in particular seemed to be downright cheerful until her first clone met its demise.
 * Alucard, Integra, and Seras of Hellsing.
 * Tabitha of Zero no Tsukaima. Before her, Tabitha was a Cheerful Child. Now she's The Stoic and very quiet.
 * Nanami of Revolutionary Girl Utena. Also, in episode 9 there is a back-story to Saionji's childhood depicting the origins of Saionji's current controlling, depressed Jerkass personality. When he was younger he was more easygoing and kinder.
 * Psyren Big Bad Amagi Miroku 'Grigori #06' is an extremely homicidal Magnificent Bastard who decided to Kill All Humans except those with Psychic Powers who are willing to help with the plan, after spending most of his childhood and adolescence as a government test subject. However, several years into being a test subject, while his twin #07 was nonresponsive and #05 had already defaulted to hate, #06 was still the sweetest kid. The fact that he held onto the hope of living as a human being the longest seems to have enhanced the virulence of his hatred once he gave up.
 * Fairy Tail:
 * Laxus Dreyar was once a cheerful young boy who idolized Makarov, his grandfather and guildmaster of the title guild. Due to the influence of his father Ivan, and his growing resentment at his accomplishments being compared to Makarov's, he grows more and more bitter until he finally tries to take over the guild by force and remake it in his own image, the final part of his plan being to beat Makarov in combat.  Later averted when
 * Mirajane Strauss is an inversion. She's very sweet and caring now, but in her younger days she was a Bratty Half-Pint who was always picking fights and constantly insulting Erza.
 * Yu-Gi-Oh! GX's Kaiser Ryo. As shown in a flashback, he used to be a sweet, idealistic kid. Somewhere along the line, he became the stoic, cold, Aloof Big Brother of season 1. It's even more jarring after he freaks out and becomes Hell Kaiser.
 * Setz from Crepuscule is shown to be a bright spirited young boy in the prologue chapters but is later shown to be a fairly apathetic, uncaring guy after the Time Skip.

Comic books

 * Magneto from X-Men. Had not the Holocaust happened...
 * The Joker, Depending on the Writer, and to the extent that he gets a childhood backstory at all, and possibly Batman himself, when given a Darker and Edgier interpretation
 * What about Batman? He's not evil, but he sure is dark.
 * There are a couple of Star Wars Expanded Universe webstrips set between the original and prequel trilogy. They cameo Ysanne Isard, Big Bad of the X Wing Series, as a little girl. She idolized her father, Director of Imperial Intelligence, back then, although her innocence was in doubt even then, since he brought her to see his work, which involved hunting down and killing Jedi. As she grew up she was groomed to be a field operative, and started cultivating connections, which worried her father to the point that he sent her on a suicide mission. She survived, came back, trumped up a treason charge, executed her father, and took his place.
 * Herr Starr, a Big Bad from Preacher (Comic Book) was this, until a bully-induced trauma that cost him an eye, his hair, and a good chunk of his humanity, before he'd even hit puberty.
 * The Garth Ennis penned tale "The Tyger" shows a snippet of the childhood of Frank Castle (aka. The Punisher). He's a quiet, thoughtful young man who does well at school and is quite close to another girl his age. Events of the one-shot however show that Frank was surrounded by the refuse left by mobsters from an early age, and it left its mark.

Film

 * Anakin Skywalker. Innocent bright eyed mother's boy who builds robot buddies turned into well... Darth Vader.
 * Subverted, or possibly entirely inverted, with Eddie from The Rocky Horror Picture Show, if we are to believe his dodgy scientist uncle, Dr. von Scott: "From the day he vas born, he vas trouble/he vas the thorn/in his Mutter's side"
 * The titular Kane from Citizen Kane.
 * Chaz, from Airheads, used to be called 'Chester' and play D&D.
 * Red Skull from the infamous Captain America (1990 film) movie. Before the Super Soldier experiment - nice kid playing on piano. After the experiment - crazy nazi with super-strength who wants to rule the world.
 * The Incredibles: as an adolescent, Syndrome aka Buddy Pine was an adoring fan of Mr. Incredible until he was seemingly brushed away by his idol.
 * The live-action movie of How the Grinch Stole Christmas does this to the Grinch, complete with a Freudian Excuse.
 * In Toy Story 3 Chuckles said of a young Lotso "He used to be such a good toy", that is until their owner Daisy accidentally forgot about them while on a picnic, after they realize this Lotso leads Chuckles and Big Baby back to Daisy's house and find that she has a new Lotso-Hugging Bear, heartbroken he convinces the others that she never loved them and became coldhearted and bitter.
 * Eight Crazy Nights: Davey was a teen basketball star and liked by practically everyone. Upon learning that, he grew up to be an alcoholic jerk.
 * Judging from the flashback, Loki from Thor had a good relationship with Thor and his father and had a penchant for mischief before the jealousy settled in.

Literature
""He seemed like a good kid, didn't he Cullen? 'Axe Boy'? Jesus, what a thing to call someone!" "Danny, our young friend 'Axe Boy' Alvin Willians chopped his mother and sister into pieces exactly one floor above our apartment. A good boy he is not.""
 * In Jonathan Carroll's novel Bones of the Moon, the main character's husband comments that the boy who lived in the apartment above them, dubbed "The Axe Boy", was always such a good boy before he was arrested for chopping up his mother and sister.

""...I remember him when he was a boy at Hogwarts. If you'd told me then what he was going to become, I'd have said you'd had too much mead.""
 * The protagonist of Vernon Scannel's poem "Incendiary"
 * The Indian Prince's boy from Raymond E. Feist's Faerie Tale, who we are told was once a nice boy.
 * The long-awaited giant children in the Chronicles of Thomas Covenant are this, until.
 * Also, from the new chronicles, Roger Covenant. Probably.
 * Kevin from We Need to Talk About Kevin was a full-on aversion of this trope from birth - or so his Unreliable Narrator mother claims.
 * Voldemort is a subversion of sorts; he's a heartless bastard who used to seem like a really nice guy who used to be a really nasty kid. Played semi-straight with Sirius Black, when Harry overhears his teacher's talking about what Sirius was like as a kid.

"Jack Crawford: You feel sorry for him. Will Graham: As a child, my heart bleeds for him. Someone took a little boy and turned him into a monster. But as an adult... as an adult, he's irredeemable. He butchers whole families to fulfill some sick fantasy. As an adult, I think someone should blow the sick fuck out of his socks."
 * Subverted when it's revealed that he's
 * And then subverted again when it's revealed that
 * And Peter Pettigrew must have been at least a good and moral person, for the Marauders to both be friends with him and to trust him with their lives as adults.
 * Francis Dolarhyde, aka the Tooth Fairy, from Red Dragon. Played for one of the more selective instances of Cry for the Devil in the first film version, Manhunter:
 * Francis Dolarhyde, aka the Tooth Fairy, from Red Dragon. Played for one of the more selective instances of Cry for the Devil in the first film version, Manhunter:


 * In John C. Wright's Titans of Chaos, Amelia thinks that the maenad she is working out how to shoot was once a sweet little baby. She braces herself by defying A Million Is a Statistic.
 * Warriors: Tigerstar, big bad of the entire series, is seen in the prequel Bluestar's Prophecy as a sweet, innocent, adorable kit who loves his mother and grows into a well-meaning but aggressive apprentice thanks to his Axe Crazy mentor. Same with minor villain Scourge, who in his backstory was an inquisitive, cute little kitten who had bad things happen to him, turning him into a Complete Monster.
 * In "A Song of Ice and Fire" the Stark Kids, before they were all broken and put on their Jade Coloured Glasses. An example that is easily missed are Catelyn Stark's memories of Petyr Baelish as a mischievous, bold and sweet-natured little boy, who believed in all the songs and started out as idealistic as Sansa
 * The general response to Sefalet with regards to her left-hand mouth in Dirge for Prester John.

Live-Action TV
"Sawyer: (to Sayid) How are you doing? Sayid: A twelve year-old Benjamin Linus just brought me a chicken salad sandwich. How do you think I'm doing? Sawyer: Sweet kid, huh?"
 * Ben Linus from Lost gets a story arc showing him as an innocent kid who was abused by his father. Also includes the Moral Event Horizon.


 * Although Ben was sorta creepy even as a kid.
 * Harry Enfield's Kevin was a well-behaved, if hyperactive, boy until he turned thirteen, at which point his hormones kicked in and turned him into the teenage horror we all know and love.
 * Beverly Hills, 90210 character Valerie Malone, revealed during  by Steve.
 * Law and Order SVU episode "Swing", Elliot Stabler's interaction with his mother highly suggests that he was a sweet kid with a dream to become an architect. His mother even suggested that he's turned out like his father.
 * In Kamen Rider Double's movie,
 * Doctor Who: The Master was apparently a sweet kid until he looked into the Vortex at age 8, and heard the drums. Then he slowly went batshit insane.
 * Invoked by name in "The Rebel Flesh"/"The Almost People", except with reference to the sweet kid's artificial duplicate.

Music
"They used to be just like me and you, They used to be sweet little boys But something went horribly askew Now killing is their only source of joy"
 * Alice Cooper, "No More Mr. Nice Guy". First person, too.
 * "I used to be such a sweet sweet thing till they got a hold of me..."
 * Although he's a pretty nice guy as an adult. The song's arguably about the way the media painted his character based on his stage appearance.
 * Averted in "Only a Lad" by Oingo Boingo.
 * The Decemberists song The Shankill Butchers:

"And you were such a sweet child"
 * Morrissey, "Used to be a Sweet Boy" and "The World is Full of Crashing Bores."
 * The song "Junge" by German band Die Arzte:

Video Games

 * King Zephiel, of Fire Emblem: Fuuin no Tsurugi, was a Well-Intentioned Extremist whose dealings with his father had destroyed his faith in humanity. In the prequel, Rekka no Ken, he's The Wise Prince who just wants his father's love. Stupid King Desmond!
 * from Fate/stay night, though in a subversion . Fate/hollow ataraxia shows this to be the case with, and Fate/Zero with as well.
 * Konnan of Dragon Fable, who used to be Yulgar's apprentice and used to look up to heroes. Then Akriloth happened. And then It Got Worse.
 * Cyrus of Pokémon Diamond and Pearl, according to an elderly couple in his hometown of Sunyshore City. Even they, however, had to admit that even from the beginning he was a little bit funny...
 * Utterly inverted by Jade Curtiss, who, when you get to know him, is actually a pretty nice guy. Then we learn about him as a child...
 * Geldoblame, the leader of the Evil Empire, is shown in the prequel Origins as the assistant of the local Reasonable Authority Figure, and helps the heroes out on a number of occasions. Near the end, we see what caused his Start of Darkness, and it ain't pretty:
 * Ace Attorney: 9 years old Miles Edgeworth was idealistic and adorable to the max. Then, Edgeworth was embedded with a severe phobia of elevators and earthquakes, and a hatred for criminals, defense attorneys, and himself after this. Even after  he still has trouble relearning the social skills he lost due to this trauma and always comes across as blunt, insensitive and cold to others.
 * Kingdom Hearts: Birth By Sleep includes glimpses into the lives of several Organization members before they became Nobodies:Ienzo was a cute Child Prodigy who follows his elders around in an oversized labcoat, and Lea and Isa were best friends. Isa is probably the worst, given how Saix is one of the most cruel Organization members.
 * In an interesting take on the trope, the Dept. Heaven series spends an entire game showing us firsthand what a sweet person Gulcasa, the Hero Antagonist of Yggdra Union, used to be before his life caved in on him just when it had started to go right. Granted, side materials and Yggdra Unison, the Gaiden Game where he's one of the main characters, go to show that he's still an incredibly nice guy off the battlefield, but given that the Sympathetic POV is kept the hell away from him for most of the main game, you'd never know it.
 * Porky Minch of Earthbound may not have ever been a "sweet kid" by any stretch of the imagination, but he was certainly a normal one. Throughout the course of the story, events slowly dragged him in and corrutpted him, to the point where he became The Dragon to Giygas, and may actually have been pulling Giygas's strings by that point. When that fell through, he disappeared into time, later resurfacing to invade and corrupt the Nowhere Islands, dismember and reassemble its wildlife, and slowly suck the soul out of Tazmily Village until everyone left for his city. All of this was done out of sheer boredom and shows absolutely no remorse for anything, believing himself to be victimised and in the right.
 * In the end, it's shown that Giygas and/or the Mani Mani Statue were playing on his desire to be liked, when he states one of his main motivations for destroying the world to be so that "...everyone who won't like me is gone."
 * The trope is almost said word-for-word by one of the characters in Soul Nomad's New Game+,.
 * Darion Mograine of World of Warcraft, as a child, loved his father and hoped to become a paladin. After sacrificing himself to save his father's soul, he became a Death Knight agent of the Lich King's will, and later, a ruthless Anti-Hero willing to do whatever is necessary to defeat the Lich King.
 * For that matter, the Lich King himself. The child we see early in his novel is something of an idealist, loves animals, and is kind even to commoners to a point he's said to spend more time with them than is appropriate for royalty, including being best friends with one. One dead horse, zombie plague, and a few questionable war decisions later, and Arthas has become first the champion and then ruler of death itself. Special attention is even brought to this with the five-year perpetual dream he had during his long sleep after taking up the crown, in which he finds two figures battling to influence him: Ner'zhul (the previous Lich King) and his own innocent child-self. Eventually,
 * Ayane of Dead or Alive, according to Dimensions, used to play with her sister Kasumi all the time, before circumstances related to Kasumi being favored, then leaving the village to get revenge for her brother caused her to become embittered and hostile toward her.
 * Inverted in Dragon Quest V; Harry is a vile, abusive spoiled brat as a boy, but years of hardship and suffering turn him into a kind, honorable and selfless young man.
 * Played straight with Terry in Dragon Quest Monsters and Dragon Quest VI. Life between the two was rather harsh between the two games (highlights include an evil king forcing his beloved sister into prostitution), turning him from an adorable heroic figure into a darker antihero.
 * In Higurashi no Naku Koro ni, used to be a cute, sweet girl who liked to collect flags and go eat outside with her parents. A car crash, which causes the death of said parents, results in her getting send to a horrible foster home where she spends "not so nice" moments. Much later, she's out.
 * Likewise in the author's other famous series, Umineko no Naku Koro ni, the main antagonist, the Axe Crazy sadistic bitch Beatrice was once . Fast forward God knows how many years and as Beatrice she now takes joy in completely slaughtering a family over and over again.
 * Here's a fun one for you. In Kingdom of Loathing, once you Ascend, you can gain access to a Temporal Rift and visit the past version of several Nearby Plains areas. One of them is Fernsworthy's Hut, the past version of Fernsworthy's Tower. Fernsworthy himself is still alive at this point, and is teaching an Ethics of Magic class. You know that cute schoolgirl who winks at you as you're leaving that scene?
 * Here's a fun one for you. In Kingdom of Loathing, once you Ascend, you can gain access to a Temporal Rift and visit the past version of several Nearby Plains areas. One of them is Fernsworthy's Hut, the past version of Fernsworthy's Tower. Fernsworthy himself is still alive at this point, and is teaching an Ethics of Magic class. You know that cute schoolgirl who winks at you as you're leaving that scene?

Web Animation

 * A bitter Jerkass today, Bitey of the Brackenwood series used to be a sweet little thing, but years of loneliness, being the Last of His Kind, and being abandoned by an adoptive family of Morrugs has changed that.

Web Comics
"Player Two character bio, Ctrl+Alt+Del"
 * "Player Two is red. He's a quiet sort of lunatic. The type everyone always says "was such a nice kid" after they find like, twenty human faces in his freezer."


 * Order of the Stick
 * Very deliberately averted in the case of Xykon - the whole point of the Start of Darkness prequel book was to show that he had no redeeming features whatsoever, and never did- in the creator's words, not only is he thoroughly evil, he's also sort of a dick. While he may not have been evil when he first discovered his gift for Necromancy at the age of four, by the age of twelve he's undeniably a Complete Monster, killing a Captain Ersatz of Professor Xavier (granted, one who was being an incredible dick about how wizards are inherently better than sorcerers), zombifying him and siccing him and his zombified grandma on his parents.
 * Played straight with Redcloak and his close-knit family, though.
 * from Looking for Group may qualify.
 * Trace Legacy from Twokinds was an OK guy, untill he tried using Necromancy to ressurect his recently-slain wife.
 * Homestuck
 * Vriska Serket may play jump-rope with the Moral Event Horizon, but as a kid she was positively adorable.
 * Rose Lalonde started off as a mature yet sweet 13-year old who just wanted to play a game with her friends so she could see her dead cat again. Once the game got started, she started communing with the Horrorterrors and wielding dark magic. She eventually turned into this.
 * Aradia can count as an example, being a cheerful Adventure Archaeologist before . She becomes the kind of person who enjoys breaking things for amusement and claiming there is no free will..
 * In The Inexplicable Adventures of Bob, Fructose Riboflavin used to be a nice little larva on planet Butane. But his dad was a highway bandit. And then his dad got killed...
 * In Sinfest, an appeal on the grounds she wasn't always a devil girl. Neither was Lil' Evil always evil
 * Sometimes used in Jack Chick tracts. Examples include Bruce in Fallen and Harry in Fairy Tales

Web Original

 * Done tearjerkingly in The Nostalgia Critic's "Commercials Special". When he's on the edge of a Despair Event Horizon, he picks up a photo of himself as a kid and angsts about how he had so much promise and dreams back then. So that sweet, "perfect" child went through a Break the Cutie (parental abuse, date rape, bullying and stalkers) and became a cynical, depressed man who has nothing left in his life but reviewing. He gets a Crowning Moment of Awesome right after, but still... ouch.
 * The Nostalgia Chick used to be an adorable girl who wanted a fairytale wedding when she was six, had quite a few friends and fell in love with a dragon because he was honorable. Then bullying, abuse, becoming a Bratty Teenage Daughter and turning to alcoholism happened, so now she's a lonely, psychopathic Broken Bird. Again, ouch.
 * Happens frequently in Survival of the Fittest if you read pre-game. Many characters come off as likable, friendly people, only to be broken once the game starts, in a good portion of cases turning Ax Crazy. As a result, you will be seeing this trope a lot, especially if the character showed up in pre-game frequently or there are any flashbacks involving the character.

Western Animation

 * In Thor Tales of Asgard it was revealed that Loki was like this as a teenager. Its not until the betrayal of a family friend and the use of Sword of Surtur that his former outlook starts souring and he begins to think different.
 * Tai Lung of Kung Fu Panda was such a cute kid in the flashback sequences that he got a lot more sympathy from audiences than the filmmakers expected.
 * Monty Burns on The Simpsons was depicted as one in "Rosebud." A flashback showed him happily playing with his teddy bear Bobo, and being referred to by his parents as "Happy." He immediately abandons them, however, to live with a "twisted, loveless billionaire."
 * Avatar: The Last Airbender
 * While hiding out in Zuko's house, the group find a picture of a smiling and sweet-looking boy and tease Zuko about it. He reveals that it's not of him - it's a picture of his Complete Monster abusive father, Firelord Ozai.
 * Zuko himself counts as this too. Even after his, Zuko is still a perpetually frowning emo loner. But in flashbacks, he's shown to actually have been a genuinely sweet, happy kid... at least until the shit hit the fan.
 * In the Teenage Mutant Ninja Turtles 2003 episode "Insane in the Membrane", it appears like this trope will be subverted when  flashes back to his childhood and is seen about to pour some sort of chemicals on a bug in a jar.
 * On The Fairly Odd Parents, Denzel Crocker was a near perfect child who was loved by everybody as a child. However,  was his Start of Darkness.
 * Amazingly, Lucius VII on Jimmy Two-Shoes. He's basically Satan (albiet a mostly incompatent one), but what flashbacks we get of his childhood paint him as actually cute and rather sympathetic, being abused by his father or the people of Miseryville. Then again, given the place he lives in, it's probably no suprise he grew up the way he did.
 * Zig-zag: In the 1993 cartoon Itsy Bitsy Spider (based on the animated short subject that played with Bebe's Kids in theaters), Leslie—the little girl who befriends Itsy—was a sweet, introverted tomboy in the short and first season. Many episodes in season two have her more tomboyish.