Eliot: Right? Angel.
Margo: Twilight.
Eliot: Buffy.
A character is aged, usually to adolescence, after being in another dimension, time travel, or other application of phlebotinum, often to get a main character's kid to "speaking age" or otherwise build them up to be able to take part in that world's adventures. Often done with clones (which would normally be born as infants), to age them up to fight the main cast. Done for the same functional reasons as the inexplicable age-up in sitcoms, and easily spotted in advance if the presence of a baby or little kid doesn't make sense in the long run.
Often the reason this happens, as opposed to simply bringing in an older character in the first place, is writers want to use some kind of girl-is-pregnant storyline, but aren't willing to wait the fifteen or so years before the baby becomes interesting. Common if the child is The Chosen One.
Occasionally, the writers will decide the age-up was a mistake (or won't be able to hold onto the age-up actor), and will revert the character back to where they started.
Differs from Soap Opera Rapid Aging Syndrome in that there is an actual in-story explanation, regardless of its believability, for the rapid maturation of the character. It should be noted that with clones it happens so frequently (mostly in order to bring them up to the same apparent age as the persons they were cloned from) that in many cases the writer does not even bother to explain how it is done. Also differs from Time-Shifted Actor, which is where two actors play the same character at different stages of their life - one which progresses at a normal pace.
Sometimes, especially for female characters, there may be an "All Grown Up" Remark. This may result in an Age-Down Romance if the now grown-up character gets romantically involved with someone of their new age.
A Sub-Trope of Overnight Age-Up. See also Time Skip, where it's the show that jumps ahead, not a character, and Rapid Aging.
Examples:
- Bleach
- Nelliel Tu Odelschwanck had her powers sealed away before the story began, resulting in her spirit becoming smaller and childlike. She regains her powers while trying to defend Ichigo, but can only maintain her true appearance for a few minutes. Urahara eventually gives her a device that stabilizes her Reiatsu and allows her to remain as an adult.
- After some rigorous offscreen training in the dangai, where time passes exorbitantly fast, Ichigo returns looking several years older.
- Doraemon: Nobita's Dinosaur has Nobita finding a baby dinosaur and deciding to show it off to his friends, Suneo, Gian and Shizuka. But Nobita wants to show them a full-sized dinosaur (lest having Suneo make fun of him by calling it a "badly-disguised lizard"), so Doraemon produces one of his gadgets - the Instant Age-Up Light.
- Used to disturbing degrees in Hunter × Hunter, where Gon forcefully causes his body to age up to defeat Neferpitou, greatly increasing his nen, at the same time shaving decades off his life span, very nearly causing him to never be able to use nen again and leaving his body a shattered and bloody mess afterwards.
- In GunBuster, they make use of a more or less realistic interpretation of time dilation as they get closer to the speed of light. This resulted in one of the characters going from sixteen to mid-40's while the main heroine, Noriko Takaya, aged a mere year or two.
- In RahXephon, Haruka and Ayato were the same age in the past; at the time of the series, Ayato is 17 and Haruka is 29 due to time passing differently inside and outside of Tokyo.
- Sailor Moon:
- Hotaru in the final season of Sailor Moon, after suffering a plot-relevant age-down more than a season before.
- Chibi Usa also goes through this when Wiseman transforms her into the Dark Magical Girl villainess Black Lady. She is healed at the end of Sailor Moon R and becomes a child again. It then happens again in both the manga's Dream Arc and a single episode of the SuperS anime, where she and Usagi actually swapped ages. The anime and the manga have different reasons and solutions for this problem.
- Str.A.In.: Strategic Armored Infantry has enough Techno Babble about sub-lightspeed travel that you never know just how old anybody is, although they all feel the age that they appear to be. The ending also ages up the entire Space Squadron save Sara herself.
- Also happens to Chris Thorndyke in Sonic X. Unfortunately when he travels to Sonic's world an inconvenient time warp sticks him back in his twelve year old body. This left the audience dealing with a more mature and useful Chris while keeping his more familiar body, making it easier for animators who had been drawing him as twelve for a couple of years now. There were certainly fewer complaints about him afterwards.
- Hana-chan forces one on herself in the first episode of Ojamajo Doremi Dokkan, turning from a baby to an 11-year-old girl so she can go to school with her "mamas" who raised her during the previous two seasons.
- In Magic Knight Rayearth, Ascot ages fast with sheer willpower because of a crush on the significantly older Umi. Having a entire world run on willpower can be useful sometimes.
- Subverted in Pretty Sammy. Washu's Dangerous Drink turns Sasami into a sexy teenager, but only for a short while: by the next day, it has backfired, and she's become a toddler. When Washu does the same thing to Pixy Misa, the result is a battle between (probably) the youngest pair of magical girls in the genre.
- Vivio, near the end of Magical Girl Lyrical Nanoha StrikerS. The villains do this to have her fight Nanoha; presumably she couldn't access her powers as a child. She eventually reverts to her younger form, after being defeated by Nanoha.
- When she gets older, she gets the ability to switch to "adult mode" at will.
- Negima! Magister Negi Magi has pills that allow one to increase or decrease your age at will. They see quite a lot of use.
- There's also a more subtle version going on in regard to Negi's constant use of various Year Inside, Hour Outside items; he's aged himself up by at least a year, if not more, in less than six months. It mirrors his ever-growing maturity.
- Reborn! (2004): Instead of 8-year old Futa also being involved in the Future Arc, his 18-year old self stays to be a competent supporting cast. Doesn't happen with Lambo and I-pin, though.
- Happens multiple times over the course of Dragon Ball:
- Most famously, Toriyama aged Goku up to his mid-teens for the 23rd Tenkaichi Budokai, something practically unheard of as far as Shonen protagonists go since their appearance tends to define their character. Akira Toriyama did it for practical reasons: he constantly had to lengthen Goku's arms and legs in fight sequences because they were otherwise too short. This was also an issue that affected Krillin, who went through the same thing and boasted he was now taller than Goku (he still wasn't). It also had the amusing effect of affecting an outfit design contest, which was started before Goku's age-up.
- At the same time, Piccolo Jr., the reincarnation/offspring of Piccolo Daimao, aged up quickly from an infant to an adult in the same timespan, to visually stand up to Goku and still believably be a threat to him.
- Gohan goes through several as he ages throughout the series, a rarity for the franchise, although two stand out. The first is during his survival training in the Saiyan Arc, where he goes from a four year old who can barely throw a punch to a five year old who has no trouble slicing the tail off a dinosaur for some breakfast. The second is post-Cell, where he goes from the boy who defeated the strongest being in the universe to a nervous high school student who hasn't fought in a decade.
- Kon from Amatsuki spends two years in the virtual world before his classmate Toki arrives there, allowing him to grow into a Big Brother Mentor figure for the latter.
- Ashura of RG Veda. Yasha found him as a baby. Just hours later, he grew up to a 5-6 year old child able to travel around. Later on, he grew to a 9-10 year old child after awakening Shura-toh. And after Shura-toh's seal was broken, he became a full grown adult.
- Aguri Madoka, alias Cure Ace of Doki Doki Pretty Cure is revealed to do this.
- Averted with Masked Cure Muse of Suite Pretty Cure ♪. It's just a disguise Ako wore to make herself looking older, including stilted boots.
- Fushigi Yuugi: Genbu Kaiden: Tegu and Hagas are twin brothers, but for VERY complicated reasons Hagas looks his age of 18 while Tegu looks like a boy under 10. Hagas, knowing that he doesn't have much time to live, brews a Self-Sacrifice Scheme and as a result, as soon as he dies, the surviving Tegu both inherits their shared title of "Urumiya" the Genbu Senshi (and the powers associated to it) and is able to physically grow up, almost instantly going from a grown man in a young boy's body to the older teen he should have always been.
- Happens briefly in Dog Days' second season: when fighting a horde of demon rats that eats the "age" from people (de-aging them temporarily), Adele gives Shinku and Gaul magic gemstones to act as protective charms. After blocking an attack from the "boss" rat, the Smoke Shield clears, revealing that the two have been aged-up to adulthood and promptly kick the demon's butt. They revert to their real ages a few minutes after everything's settled, but not before the girls present have ample opportunity to Squee over how handsome Adult! and Gaul look.
- In Toward the Terra, when Nazca is under attack by the Meggido, the seven Children of the Mu instantly age themselves from toddler to teen and teleport themselves into space to reenforce the shield Blue and Jomey have just created.
- Dr. STONE: During the South America arc, the heroes are forced to cause a second mass petrification event, turning everyone on Earth into stone. Suika, an 11-year-old girl, is the only one affected by the automated revival fluid delivery system that was prepared beforehand, and by the time she's managed to make more revival fluid, several years have passed, making her a teenager while everyone else hasn't aged physically.
- In One Piece, eight-year-old Kozuki Momonosuke gets Shinobu to age him up by twenty years so he could assist Luffy in his ongoing battle with Kaido, debuting in his adult dragon form in Chapter 1023. His human form isn't shown until after the battle with Kaido is over, when he reveals himself to the general population of Wano in Chapter 1051.
- The 24th volume of Kocchi Muite! Miiko has a chapter where Miiko, Mari, and Momo going to a shrine during New Year and Momo wished to be older. She got her wish granted and went from one to eleven-year-old. However, her sudden growth spurt doesn't let her mature properly and she still act like a baby. Eventually they return back to the shrine and Momo reverts to her old self after undoing her wish.
- Marvel Universe:
- Illyana Rasputin of New Mutants went from six to thirteen in the middle of a rescue attempt, due to a time rate differential between Earth and the hell-dimension in which she was trapped. Nowadays, she fluctuates between being around an older teenager to being in her early twenties.
- The same happened to Marrow, only with her place being a pocket dimension called "The Hill".
- Fellow X-character Nathan Christopher Summers is sent into the future as a baby and later comes back (roughly the same age as his grandfather) as Cable. He came back before he left, so at one point, both Adult Cable and Baby Cable were around at the same time.
- And now we have Cable's protegée, Hope. It involves a lot of different futures.
- Nate Grey, a.k.a. X-Man, Cable's counterpart from the Age of Apocalypse, was created from the DNA of Jean and Scott, then aged up into the ultimate telepath and telekinetic.
- From X-Factor: Layla Miller's barelylegalification has her going to the future and coming back.
- For a while even Reed and Sue Richards' son Franklin fell victim to this trope, being kidnapped into the future and coming back as the teenage Psi-Lord. Silly, yes, but it did give young Franklin's tremendous mental powers a break from Deus ex Machina and/or Puberty Superpower duty - his older self was in control of them. It was later reversed.
- Captain America's Arch-Enemy the Red Skull used his Deus ex Machina to age his daughter Daddy's Little Villain Sin from a 13 year old Creepy Child Enfant Terrible into a 23 year old Axe-Crazy Dark Action Girl that makes her father look sane by comparison.
- Tommy and Billy, the twin children of the Scarlet Witch and The Vision, died as infants, but were reincarnated as teenagers years later in Young Avengers.
- in Young Avengers Vol. 2, Kid! is aged up to Teen! by Billy's magic in a plot to get his powers back. It worked to an extent.
- This has the fortunate side effect of now making him resemble Tom Hiddleston.
- The Hulk's sons Skaar and Hiro-Kala are physically young teens, but chronologically only a couple of years old, partly thanks to their mother being one of the alien Shadow People, who have an accelerated maturation rate. Skaar actually has a "puny" (human) form that is at least still a child.
- When you consider Skaar's the first Hulk "person" to grow up from birth on-screen, his growth, muscle tone and mental development rate may be the norm. To give reference, in Skaar Son Of Hulk #1 even as a newborn Skaar appeared to be nearly as large as one of Miek and the Brood's offspring and stronger than them.
- Most of Marvel's clones were subjected to accelerated aging, mostly to bring them up to the age of the persons they were cloned from and make them indistinguishable from them. Examples include the clones of Gwen Stacy and Spider-Man (Ben Reilly and Kaine), Jean Grey's clone Madelyne Pryor in the main timeline and either Spider-Girl or May "Mayday" Parker and April Parker in the MC-2 universe.
- In the Ultimate Universe, Peter Parker was cloned (at least) five times (including different-sex clone Spider-Woman). Four were force-aged to Peter's age, one was aged to that of his father in order to impersonate him. This last clone did not stop aging more rapidly than normal and died of it.
- Norman Osborn artificially aged his twin children by Gwen Stacy so that currently they are the same age-group as their late mother. Sinister War later revealed that the children weren't his nor Gwen's, but genetically-created kids made by Norman's son Harry in a plot to screw with both Norman and Peter.
- The Mighty Thor inverted this, giving Loki a Plot Relevant Age Down where he was reincarnated as his child self after dying. It avoided being Narm or too heavy-handed when an echo of the older Loki revealed his reasons for having it happen. Preteen Loki has been hugely popular, making it work very well. And then he got two age ups as well. The first is the one mentioned under Young Avengers (to young adult) the second happened in Loki: Agent of Asgard when the jerk chose to remake themself rather than turning evil evil again (to thirty something).
- The Avengers #200. Ms. Marvel (Carol Danvers) is impregnated, gives birth, and her child ages to adulthood within minutes.
- Illyana Rasputin of New Mutants went from six to thirteen in the middle of a rescue attempt, due to a time rate differential between Earth and the hell-dimension in which she was trapped. Nowadays, she fluctuates between being around an older teenager to being in her early twenties.
- The DCU:
- Black Orchid: The younger Black Orchid Suzy was originally a young girl in her debut in the 1988 Neil Gaimain miniseries, but in the 1993 ongoing eventually aged up to adulthood to take the place of her predecessor Flora Black after her Face–Heel Turn and death.
- Alexander Luthor, Jr. (the son of Lex Luthor's heroic Earth-3 counterpart) accelerated to adulthood shortly after he was born in Crisis on Infinite Earths.
- Arisia from Green Lantern physically ages herself from about 13 Earth years to at least 18 Earth years so she can pursue a crush on Hal Jordan. Later, to make Hal Jordan not look like a skeeve, this was subject to several Retcons, and, in current continuity, 13 years on her world are equivalent to 240 on Earth.
- While the Phantom Zone normally suspends aging, Superman's son Chris -who had become imprisoned in Last Son- emerges from its imprisonment as a teenager in New Krypton.
- In Supergirl (1984), Kara, who is a little kid at the beginning of her cosmic trip, rapidly ages to teenhood when her ship goes through a space warp. When she lands on Earth, the warp's energies have turned her into a seventeen-year-old young woman.
- Infinite Crisis did this to Bart Allen/Kid Flash via spending four years in an alternate dimension accessed via the Speed Force, thus turning him into someone old enough to be the new Flash while Wally and his family were on another planet. He was then the new Flash for a while until Inertia, his Evil Twin, got the Rogues Gallery together and killed him, perhaps to make room for Wally's return.
- Interestingly, the reason Wally was off on the other world was to deal with his speed-powered twin kids who were receiving the same treatment- they're chronologically less than two but look eight or so, and nobody knows if their aging has truly evened out or if it's temporary: any given morning Wally and Linda could wake up to find them teenagers or senior citizens or dead, so they're being rushed into the Family Business.
- Bart himself was subject to this in his first appearance in the 90's - chronologically, Bart was two, but appeared about 12 due to hyper-accelerated metabolism. He was initially raised in a virtual reality machine to offset the mental age difference, and then brought to Wally so the older speedster could shock Bart's metabolism into a normal pace by challenging him to a race. In the short space of time between his removal from the machine and Wally fixing his aging, Bart aged up an additional two years to 14 - any longer and he would have likely died of old age within a week.
- Duela Dent, "The Harlequin", was a '70s Teen Titans character who was apparently the daughter of a post-Two-Face Harvey Dent. As her age never made sense with the timeline (otherwise she would have been a small child instead of a teenager), Marv Wolfman had her origin revealed as a lie in the pages of New Teen Titans, while George Perez drew Duela to suddenly look as if she were in her thirties or forties to emphasize that she had to be too old to be Two-Face's daughter. An older Duela was also briefly seen as an asylum patient in Team Titans, although when the character was formally allowed back into Titans continuity, later artists and writers aged her back down.
- Other Titans, Hawk and Dove, underwent this in a guest appearance in The Brave and the Bold in the 1970s. Overlapped with a bit of a Continuity Snarl, as Hank and Don were aged up to being adult men while the rest of the DCU didn't age with them. Marv Wolfman then poked fun at the continuity error in their cameo at Donna Troy's wedding, with the college-aged Hank and Don being baffled when someone had the impression that they were much older.
- Superman (Brian Michael Bendis) has Jonathan Kent aged up from 10 to 17 despite only being gone from Earth for only three weeks.
- Right before the Sonic Adventure arc of the Archie comics, Amy Rose does this to herself with a wish to justify her joining the party; otherwise, the rest of the gang would've forbidden her from joining for being too young, and the whole game tie-in thing would fall apart.
- Apparently the same thing happened to her negative-dimension counterpart, Rosy Rascal, although her reasons for wanting to be older weren't quite so noble. It had the side effect of breaking her brain, turning her into a dangerous psychopath. And you thought Amy was possessive...
- Jenny Quantum of The Authority does this to herself. After meeting the incarnations of centuries past and becoming aware of the current problem, Jenny uses her quantum powers to go from six years old to high school age.
- Gold Digger (Antarctic Press) has Brianna, an accidental composite clone of Brittany and Gina. She was born fully grown, with both sets of memories, and had to establish an identity for herself. It was eventually established that some of her more childish personality traits owe to the fact that her soul is still her real, chronological age, and never got to experience a real childhood. Her sadly deceased granny was the only person insightful enough to treat her with the level of affection she would give a little girl.
- Happens to the main character of the My Little Pony: Friendship Is Magic fanfic The Twilight Child in an attempt to give herself wings, which only results in aging herself by four years. Deconstructed since as a result she skips straight into full-blown puberty, with all the problems that lie therein, and her suddenly larger body takes some time to get used to, both of which make herself even more of a social outcast than she already was, and no attempt to "undo it" will work. And she doesn't get any wings anyway. It's later revealed that part of the reason it can't be undone is because of the Nightmare possessing Twinkle. It's finally undone when the Nightmare is removed from Twinkle's body for good.
- In The End of Ends, Beast Boy undergoes one after being possessed by the Dark Prognosticus.
- The A Song of Metal and Marvels series has had a few examples so far:
- In the epilogue of A Man of Iron, the Night's Queen possesses Sansa's corpse, resurrecting it and aging it from her early teens to adulthood.
- In the last third of A Crack of Thunder, Arya and Gendry are exposed to a magic ritual to activate their mutant powers, which as a side effect ages them up to late teens and adulthood, respectfully.
- Also in A Crack of Thunder, Rickon is sucked through a magic portal, and reappears many chapters later, having aged into an adult (specifically, he's become Star-Lord), due to time running faster in the dimension he was taken to.
- In Over the Rainbow, Ozma has aged up to roughly 18 or 19. People don't need to age in Oz, but Ozma decided to age accordingly with Dorothy just in case Dorothy ever comes back to Oz.
- In EVA Sessions: Someplace Vast and Dry, Kaworu Nagisa is deliberately engineered by SEELE scientists to be physically ten years old in a span of six months, as Lorenz Kihl intends for him to be around the same age as Rei, Shinji and Asuka.
- Patient: Dorothy is aged up to seventeen so that she can have a romantic relationship with Ozma.
- The MLP Loops: Invoked. The loopers have been stuck in a "Groundhog Day" Loop for a very long time, and have access to age-shifting magic. So the looper children will often find an excuse to suddenly age themselves up so that they can actually be adults. For Spike and Rarity's wedding, they "accidentally" fell through a portal that supposedly made ten years pass in moments to justify him being an adult and old enough to marry. When Diamond Tiara is part of the Elements one loop, she uses the big initial blast as a cover.
Diamond Tiara: [monotone] Oh no. What have the Elements done to me? I'll never finish school now.
- Harry is literally aged up three years, for all intents and purposes, including legal matters and magical sensors, during his transformation in The Awakening of a Magus.
- Abandon All Hope, Embrace All Chaos has this happen a couple of times, due to the time variance that comes from traveling into the Warp or through it into another universe:
- Both the Powerpuff Girls and the Rowdyruff Boys undergo this when the Emperor takes them to his universe for training to make them his elite warriors against Chaos. Deconstructed as several characters feel like the six's childhoods have been stolen from them for the sake of a war; also, Blossom's relationship with Dexter is terminated due to him still being an adolescent while she and the others are now adults.
- Likewise, both Mandy and Gaz are taken into the Warp for training by the forces of Chaos to become Daemon Princes, and come back with their human forms now being adults.
- Played for Horror with Sartile aka Timmy Turner, who was turned from a young boy into an Astartes via the Daemonculaba.
- In The Return of Hanuman, Hanuman reincarnated as Maruti rapidly ages into an elementary school student in three months in order to quickly help an elementary school boy from being bullied.
- Saphira in the film version of Eragon. In the span of exactly one minute, she goes from a cute baby/child dragon to a fully grown adult capable of speaking telepathically (in an audibly adult female voice) and carrying Eragon on her back. This effect comes complete with flashing lights, sound effects, and a generous smoke screen to hide the actual transformation.
- Eragon blessed a baby who grows to about four years old in her next appearance. It turns out he actually cursed her, forcing her to eat huge amounts of food, making her mature mentally and physically at a rate far faster than normal. It Makes Sense in Context.
- In Warlock (1989) the titular Evil Sorcerer cursed the heroine to age by 20 years each day just For the Evulz. However, she managed to reverse the spell and restore her youth.
- In Excalibur (1981), Morgana ages her son Mordred from a child to a young adult in order to face Arthur in combat.
- In The Ice Pirates, Karina gives birth to and raises a son to adulthood while the ship is passing through a time-warping zone. The journey takes only a few minutes of screen time.
- In Dinocroc, the titular creature is roughly the size of a large dog in the opening scenes. Cut to a few days later and it's grown to the size of a large truck able to fit an entire teenager over the length of its jaws. It was engineered to have a ludicrously fast growth rate and was said to have previously grown about half a meter in a single day.
- In Douglas Adams' novel Mostly Harmless, Trillian's daughter Random goes into an intergalactic daycare as a preteen and comes out past puberty. It turns out the daycare was also temporally displaced, and the time you come back is random.
- This is the main plot of William Sleator's Singularity. One twin locks himself inside a Year Inside, Hour Outside device, so that he'll be a year older than his twin and thus no longer a twin.
- Wyrd Sisters: A three-year-old Rightful King is useless, but an 18-year-old Lost Prince is generally pretty reliable when it comes to overthrowing the Usurper. So the titular witches send the Prince away, then move the entire kingdom 15 years into the future, so the people won't have to suffer under the mad duke.
- In the last of Piers Anthony's Apprentice Adept books Wunderkinds Flach and Nepe age a decade between chapters. A good chunk of the cast is hiding out in a hidden underground stronghold, magically gimmicked to speed up time twenty-fold.
- In The Gap Cycle by Stephen R. Donaldson, Davies Hyland is force-grown from a fetus to a 16 year old teen. He's also implanted with the mind of his 22 year old mother.
- In Cordwainer Smith's story The Dead Lady of Clown Town the major character D'joan (later Joan) is force-grown from age five to age sixteen in one night.
- In the Magic: The Gathering book Legions, the reincarnated Kuberr grows up in the course of a few weeks. Justified in that he is a reborn god (of wealth no less) born of Phage and the Patriarch (who are basically incarnates of death themselves) and is actually growing at a rate that corresponds to the number of deaths in the world, while a war is going on.
- In the Animorphs companion and backstory book "The Andalite Chronicles", Loren ages from about 13 to around 18 in the course of a few minutes after a botched attempt at using the Time Matrix strands them in a weird, mixed reality: at the center is a time paradox, explained with lots of Techno Babble, that basically runs much faster than normal. They have to enter here to regain the Time Matrix and travel back home. Loren uses its ability to hedge the details of reality to make sure nobody at home notices, either.
- In The Snow Queen by Hans Christian Andersen, Gerda goes on a heroic pilgrimage taking at least a year, possibly more, to rescue her friend Kay from the Snow Queen, after he was inflicted by a shard of the devil's mirror and turned cruel and cold-hearted. But when they arrive back home in their garden, they turn to find themselves both adults. Poetically, the whole adventure portrayed their adolescence.
- In the Doctor Who New Adventures, teenage Action Girl Ace gets betrayed by the Doctor one too many times, and leaves him. Four books later, the Doctor arrives in almost the same time period, and cynical twentysomething mercenary Ace rejoins the TARDIS crew.
- Star Trek: New Frontier does this to Xy, the son of Burgoyne and Selar. In the three-year gap between Stone and Anvil and After the Fall, he goes from young toddler to science officer. The reason is that the combination of Vulcan and Hermat DNA makes him age super-fast...but it also means that he'll die before either of his parents. That is, until his mother gives her life to get him a means to extend his life in Treason.
- The first year in the mill in Krabat counts as three. Becomes important because at the beginning of the story, Krabat was too young to be interested in girls (and he needs a girl to defeat the villain). Justified by magic.
- About a third of the way through Jerry Ahern's Survivalist series, the Earth's atmosphere catches fire (don't ask; it's nonsensical but awesome). John Rourke and his family and two best friends have managed to gain possession of some suspended animation booths, and go to sleep for the estimated 500 years it will take for the oxygen level of the atmosphere to recover sufficiently. Unbeknownst to the others, John sets his booth to wake him up about twenty years early. When he discovers that there's enough air to get by Denver-style, he wakes up his 8- and 6-year-old children, spends a few years teaching them survival basics, and then goes back to sleep himself for another decade-and-a-half. Then all the adults wake up as scheduled to find that the kids are suddenly twenty years older than they remember (Mom, in particular, is pissed). John doesn't attempt to dress up the fact that he did this in order to make their little group into three possible breeding pairs rather than the two it would have been (no, not the siblings; the daughter with the other adult male and the son with the other adult female), just in case it turned out they were the only surviving humans. They weren't, but it was a very pragmatic plan, and the predicted couples did end up together eventually anyway.
- In H. P. Lovecraft's The Dunwich Horror, Wilbur Whateley grows to young adulthood within five years of his birth.
- In Time Scout Armstrong, Marcus, and his children run to Denver, then to London. They show up in London a few hours before they leave for Denver, three years older. Tragic, as it means that Ianira has lost three years of her children's lives.
- In Darke, the sixth book of Septimus Heap, Jenna and Septimus have gone from 12 years in the preceding book Syren to 14 years, where he will have to have the Darke Week and she will become Queen.
- The title character of The Saga of Darren Shan had been turned into a half-vampire in the first book of the series, when he was 12. This meant he aged one year in every five, so when he was thrown into a vampire war fourteen years into the series, he looked to be around 15. Cue came the "Purge", basically the half-vampire counterpart of pubescence, which allowed him to age up a few years.
- In Galaxy of Fear: Army of Terror, Eppon is found appearing to be a year old, but whenever he's alone with someone he eats them and gets older and larger. Within hours he seems to be a teenager. Soon after that he turns into a monster. Though people initially assume he's an orphaned human, they quickly conclude that he's not.
- The Tendu of The Color of Distance have multiple stages in a mature life cycle. Egg, narey, tinka, bami, elder, and enkar. Eggs become narey and narey become tinka on their own, but the other stage changes are induced by mature Tendu. The bami Ani becomes the elder Anito in one short session, as The Determinator tinka becomes the bami Moki later. Tinka-bami is the most extreme change, as it comes with sentience and being seen as a person.
- Rayford Steele's son Raymie Jr., who was in his early teens when he was raptured along with his mother in the first published book of the Left Behind series, comes back at Glorious Appearing in the form of a twenty-year-old with his new glorified body, becoming one of the members of the Millennium Force during Kingdom Come along with his "natural" nephew Kenny Bruce Williams.
- The Last Day of Creation by Wolfgang Jeschke. On arriving back in the past, the time travellers discover things have Gone Horribly Wrong and their expedition has been scattered across decades. This only sinks in to the protagonist when he encounters someone he knew a couple of days before who was in his thirties, who is now a senile old man.
- Angel:
- In season 3 when Angel's son Connor was born, kidnapped, and carried off into another dimension where time moves faster, he comes back as a 16-year-old. His kidnapper counts too, leaving Earth as an adult and a relentless vampire hunter, only to come back as a feeble old man.
- Also used when Buffy apparently kills Angel, but actually sends him to a hell dimension at the end of season 2. When he returns months later in Season 3, he is actually several centuries older. Being an immortal vampire, he looks exactly the same. His mind, on the other hand...
- This happens to Billy in the Power Rangers Zeo two-parter 'Ranger of Two Worlds' due to a Real Life Writes the Plot scenario because his actor, David Yost, had left the show during the 'King For a Day' two-parter due to what Yost claims was homophobic treatment of him due to being a gay man in the mid-1990s. Like with Austin St. John, Thuy Trang, and Walter Jones in season 2 of Mighty Morphin' Power Rangers, the producers had to come up with an explanation as to why Billy was no longer there due to David Yost's quitting before a proper farewell arc could be written like they'd done for Kimberly the previous season. It is hard to say if he would have been given the 'leaving for/staying on Aquitar' general plotline if he'd stayed and been written off with everyone else in Power Rangers Turbo; a query of fans on the Power Rangers subreddit seems to indicate that he may have been sent elsewhere on Earth instead of off-world like he is in Zeo-like going off to MIT or another big tech or science-heavy college.
- Percy goes from a teenager to an adult in between the two seasons of Starhunter, despite supposedly being trapped where she couldn't age at all. This is likely due to Dawson Casting: Percy was played by 25-year-old Tanya Allen, and, since the second season was filmed 3 years later, she couldn't pass for a teenager anymore.
- The 4400: At the end of "Mommy's Bosses", the one-year-old Isabelle is aged to adulthood overnight. She appears to be in her early 20s but the next episode "The New World" makes it clear that she lacks the corresponding emotional development. She has trouble grasping the concepts of good and evil.
- Star Trek, from The Next Generation on, uses this a lot, almost always in the form of using Bizarre Alien Biology to Hand Wave Soap Opera Rapid Aging Syndrome:
- Star Trek: Deep Space Nine actually does a one-shot of this trope in "Time's Orphan", in which the O'Briens' toddler daughter Molly falls into a time portal and grows to adulthood before coming back. Fortunately, when she goes through the portal again, it sends her to the same time as before, and she sends her younger self back.
- They also did this with Worf's son Alexander, justifying it by establishing that Klingon children mature very fast. Alexander was played by several different actors and always behaved about as old as he looked. Deep Space Nine really pushed it by making him physically and mentally a young adult at the chronological age of, oh, seven. (The fast aging is especially odd if you consider that Klingons also live longer than humans, a fact established so Klingons from Star Trek: The Original Series could show up.)
- Klingons aren't alone in this, by the way. The most extreme example is Star Trek: Voyager's Kes, whose race has a nine-year lifespan. In one alternate future episode, Kes had a daughter with Tom Paris... and that daughter was old enough to marry Harry Kim within a year or two.
- Deep Space 9 also has the Jem'Hadar, who age incredibly fast because of special genetic modifications.
- Voyager also has Naomi Wildman, who is 1/2 Human, 1/2 Ktarian. At age 2 chronologically, she looks and acts like an 8-year-old Human. This was justified In-Universe by her half-alien biology. Another side effect is her gestation was approximately 18 months.
- Another Star Trek: The Next Generation example: in "The Child", Troi goes from being newly pregnant to having a baby in a few days. The kid then grows from babyhood to about ten years old in a similar space of time, before "dying". Turns out the "kid" was a benign energy-based alien who wanted to experience corporeal existence, and was grateful for all the affection Troi showed "him". This was actually one of the first episodes to really cement Troi's position on the show and make her something other than a walking plot device to read minds. This may be explained, however, by the fact that the episode was one of those originally written for Star Trek: Phase II before that series was scrapped and replaced by the first movie. The original script centered around Lt. Ilia.
- In Star Trek: Picard, Guinan appears significantly aged from her last appearance despite her species' extremely long lifespans, explaining that El-Aurians have the ability to control their aging process and she opted to age alongside humans because humans get weirded out by someone who doesn't age, while Q shows up looking the same as he did the last time he made an appearance only to see how much Picard has aged and snaps his fingers to appear older to mock Picard.
- Tenavik in Star Trek: Discovery ages from a baby to an adult in a few months due to proximity to time-altering time crystals.
- Stargate SG-1:
- In the final season, Vala gives birth to Adria, who is introduced as a plot point. Adria is an engineered leader of the bad guys who grows to adulthood in just a handful of episodes.
- Adult character Teal'c was also aged to extreme old age for his species due to Time Travel. He had to go back in time to prevent the problem they'd spent the last fifty years on, so his change is for keeps, carrying over to The Ark of Truth and his Stargate Atlantis guest appearance.
- There was also the episode where Jack O'Neill is aged to geezer status... by a nanotech STD, no less!
- Supernatural:
- Amara ages from a baby to a full-grown woman over the course of less than a season. She can probably appear whatever age she cares to be, though, since she's actually God's twin sister, the Darkness.
- Jack ages rapidly from a baby to having the appearance of a teenager. Well, he is a Nephilim.
- Power Rangers S.P.D.: child villain Mora is turned into adult villain Morgana... which turns out to have been her true form all along. But she prefers being a child and gets herself changed back.
- Happens more than once during Xena: Warrior Princess:
- Gabrielle's daughter Hope does so and becomes her mother's Evil Twin.
- Inverted later when Xena and Gabrielle go to sleep for thirty years in coffins of ice and awake to find Xena's daughter Eve has aged to adulthood.
- Examine the case of Walt from Lost: he began the series as a 10 year-old. However, because the first three years of the show covered only the last three months of 2004, actor Malcolm David Kelley quickly grew older than his character. Thus the character was written out in season 2. When the series time-jumped three years after the rescue of the Oceanic 6, Walt returned in a few appearances, having aged appropriately. However, in the season 3 finale, Walt appears to Locke in December 2004, looking as the actor did in 2007. This appearance was referred to in-show as "taller ghost Walt."
- Ultraman Mebius takes place 20 years "real time" after the last monster attacked and brings back everyone except Taro's actor.
- In HEX, Malachi does this, going from an infant to a teenager in a year, due to being half-demon.
- Doctor Who:
- In "The Eleventh Hour", the newly regenerated Doctor meets the little girl Amelia Pond, who asks to travel in the TARDIS, and the Doctor accepts. Of course, having a little girl around in a show where there's usually at least one death every episode would be a bit dark — and besides, a eight-year-old can't do Fanservice. So having the Doctor accidentally jump 12 years into the future means that we can now have an all grown up Amy travel with him.
- Doctor Who also has the fastest age-up yet seen. River Song is introduced as an adult ("Silence in the Library") three years before she is born ("A Good Man Goes to War") and two years before her parents joined the cast.
- In V (2009), Ryan's daughter is aged up from a baby to a 7-year-old because she is used to test the rapid aging treatment that is used for Lisa's replacement.
- The original V (1983) did this with Elizabeth (twice!), supposedly because of her Half-Human Hybrid status.
- Liam Kincaid from Earth: Final Conflict grows from a newborn to adulthood during the first part of the first episode of the second season. Explained by his being one-third alien.
- The West Wing has an Inversion: when Zoey Bartlet was introduced in the first season, she was stated to be 19. In season 2 they decided that she was actually 17 so to add drama to the MS storyline.
- Babylon 5:
- In "Babylon Squared", a Starfury pilot passes through the time field around Babylon 4 and dies of old age.
- Inverted with Draal, Delenn's mentor, after he takes control of the Great Machine in "A Voice in the Wilderness, Part 2". The Machine's life support functions age him down from a man in his seventies to a man in his forties. However, this was not plot relevant, but rather an excuse for the unavailabilty of the original actor.
- Played straight in "War Without End, Part 2". Due to Sinclair having passed through the time field around Babylon 4 back in "Babylon Squared", when the team begins traveling back in time, he rapidly ages. This turns out to be why he couldn't allow Garibaldi to come on the mission.
- Space: 1999: In "Alpha Child", alien influence causes a newborn baby to age instantly to 5-6 years old, allowing him to interact with the Alphans. He subsequently ages again to become Julian Glover in Space Clothes.
- On Heroes Reborn, Tommy and Malina were actually born in 2014, the day of the Odessa bombing. The fact that they are Claire Bennet's children made them a target for Renautas Corporation, who planned to exploit or destroy the children. In order to protect them, they were taken back in time to 1999 by Hiro Nakamura alongside their great-grandmother Angela Petrelli and grew up normally so they would be teenagers in 2015.
- Gotham has a character named Marv with the power to rapidly age others. Normally he uses this to kill people by making them two centuries old, but an attack on a pre-teen Ivy Pepper is interrupted, leaving her physically in her mid-20s.
- Super Sentai has several of these. Most of which happen with villainous characters:
- Choujin Sentai Jetman has Tran, a young boy with telekinetic powers. After being bullied by the other villains for his ineffectiveness against the Jetman, he forces himself to grow up into the much more competent Tranza.
- Chouriki Sentai Ohranger: After Emperor Bacchus Wrath was killed by the Ohrangers, the Machine Empire Baranoia is briefly taken over by the usurper Bomber the Great, who promptly dispatches himself of the young prince Buldont, who was officially first in line to the throne. Since all the villains are robots, Buldont is subsequently rebuilt in secret by Empress Hysteria, into the much more powerful and adult Kaiser Buldont.
- Bakuryuu Sentai Abaranger: The Big Bad Dezumozorlya is a parasitic godlike being who needs hosts to survive. His mostly used host in the series is Lije, a young girl who's revealed to be the baby daughter of Mahoro and Asuka, aged up into a 12 year old girl. Dezumozorlya later ages his host up to the adult Lijewel, in order to more effectively fight the Abarangers.
- Ressha Sentai ToQger reveals mid series this actually happened to the ToQgers themselves as they were kids forcibly grown into adults to better combat their enemies.
- In Season 6 of Once Upon a Time (2011), Rumplestiltskin and Belle's son Gideon is aged from a newborn to a twenty-eight through being kidnapped by the Black Fairy and held in another realm where time moves differently. Somewhat justified as it's a prison realm to contain the Black Fairy and the series has shown that in some realms like Neverland time flows differently.
- At the beginning of season 5 up until the end of season 6, Robin is an infant. In season 7, she's twenty-five. The rest of her family doesn't quite match this time gap, but Zelena excuses this when talking to Regina by referencing the fact that Robin grew up in a realm where time moves differently.
- On Killjoys, Jaqobis, D'avin's biological son with Aneela, ages from a baby to a teenager in a few days after being born, though they are able to slow down the rapid aging before he ends up too old.
- Discussed in The Magicians (2016). When the Fairy Queen claims that Fray is Eliot and Fen's infant daughter aged up to young adulthood in the two months since she was taken to the Land of Faerie, Eliot and Margo are skeptical, and compare it to instances of this happening in pop culture — they namedrop Buffy the Vampire Slayer and Twilight.
- In True Blood, Andy's daughters literally age overnight - multiple times - but this is because they're half fairies.
- WandaVision: Early in the series, Wanda gives birth to twins, Billy and Tommy. The twins are infants at the start of Episode 5, but quickly age themselves up to become five-year-olds, and later turn ten so they can adopt a puppy. Later in the episode they are about to do it again before their mother stops them.
- In The Thundermans, Chloe’s birth shows that Super pregnancies and births are rapid, with the child going from fetus to toddler over the course of a day. After they reach toddlerhood, then they age naturally.
- In The Gamer's Alliance, the half-god Nyanna Mikoto's body, despite actually being only a few months old, has grown to resemble a 7-year-old's thanks to divine magic and her unique powers which she can't quite control yet. She has also learned to communicate thanks to the magic of her mother although she has problems grasping basic concepts such as what a 'father' is.
- Aurora of Child of Light gets aged from a young girl to a teenaged lady after obtaining the Stars and Moon. The Sun takes her to adulthood.
- In Final Fantasy IV, Rydia, a young girl when the party first encounters her, is swallowed by the Leviathan and carried into the Eidolons' land of Feymarch. When she is reunited with the party, presumably no more than a few weeks later, she has aged into her early twenties because time passes ''much'' more quickly in the Feymarch.
- Notably, when you actually travel there, you don't get any older. However, this makes sense as we see this visit from inside the Feymarch and its faster time stream; outside, presumably, mere seconds pass before the group exits again.
- Ran in Twinkle Star Sprites ages to somewhere past puberty when she powers up and becomes Princess Sprites. It doesn't last — she becomes a little girl again at the end of the game.
- Metal Gear-verse clones age normally up until the time when senescencenote starts to set in, which then hits them like a train. This was used to age the main character, Snake, from a young and handsome hero in his early thirties into an Older and Wiser forty-something in the space of only two years in chronology. In Metal Gear Solid 4, despite the fact that he is chronologically in his early forties, he is, by all appearances and genetic testing well into his seventies. Heck, he looks older than some eighty year olds in the game. Prior to this, Snake and Raiden had seen how hard the aging hits with Solidus Snake in Metal Gear Solid 2—despite being chronologically younger than Solid Snake, the Patriots had engaged his accelerated aging process early so that he would appear to be middle-aged during the events of the first game and thus would be able to fit in the role of being the Patriots' puppet President of the United States. As the elections were rigged, the Patriots needed to make their candidate seems as plausible as possible to maintain their charade. By the time of the game's events, Solidus's accelerated aging has gone even further and he rather resembles Snake in Metal Gear Solid 4.
- In Shadow Hearts: From The New World, Johnny ages-up when in a late-game transformation form. That is, he becomes his true age while transformed.
- In Super Marisa Land (A Touhou Project version of Super Mario Bros.), Marisa starts as a toddler but ages up and down depending on how many power ups she has.
- Woodruff and The Schnibble of Azimuth starts with Woodruff, a toddler, aging into an adult after his adoptive father Azimuth sticks a device on his head. This device turns out to be an age-adjusting device Azimuth had built as part of a plot to kill the Bigwig. When the Bigwig's men came to capture him, he used it to age Woodruff up so that he could carry on the work; when you meet the (newly-teenaged) Azimuth later, he gives it to you, and you yourself use it to age the Bigwig to dust.
- In the Warcraft universe, the young archmage Khadgar vanquished his close friend turned Fallen Hero Medivh by magical means, and in the process suffered a one-off curse that caused him to prematurely age. By the time adventurers re-discover him in the Burning Crusade expansion, he is chronologically in his late 30s or early 40s but physically much older.
- As well, a number of orcs were aged into adulthood by the warlocks to fill the Horde's armies. One notable subject was the half-orc Garona, as part of an effort to un-snarl her continuity from a series of timeline Retcons.
- The Fan Remake of King's Quest 2 has this apply to Possum when she becomes the vampire Anastasia. Meanwhile, the inverse happens to her grandmother when she also becomes a vampire.
- In Breath of Fire I, Nina gets sent into the past and suffers amnesia, and spends a few years under the care of some friendly townspeople until you find her and restore her memories. During this time, she has grown older and has developed new abilities, such as being able to become a great bird.
- Hyperdimension Neptunia Victory does this in order to disassociate two characters with each other. Yellow Heart is forcibly adjusted to give her an adult body in order to take full advantage of her insane strength. Her normal form, a kidnapped Peashy, is still a child. Once her memories are restored, she can transform into "the big me" at will.
- In the Sengoku Basara series, Ieyasu goes from a Bratty Half-Pint to an incredibly muscular and rather attractive adult in the third game. Particularly unusual in that almost none of the other characters mention this transformation.
- In The Walking Dead, Clementine goes from 8 at the beginning of Season One to turning 9 just before the end. After the time skips in Season Two Episode 1, she's now 11. Time has skipped once more in season three, putting her at the age of 13. Season 4 is set around three years later, with Clem being 16 years old.
- Xenoblade Chronicles 2 zig-zags this with its own Robot Girl, Poppi. Her initial Poppi α form appears as a young girl. A bit further into the game, she is upgraded to Poppi QT, resembling a teenager, and a late-game sidequest unlocks Poppi QTπ, an adult. However, she can switch freely between all three forms, and mostly stays as Poppi α in cutscenes.
- Xenogears has the Robot Girl Emeralda Kasim. At first she has the appearance of a child, but after a sidequest involving her origins, she becomes an adult with stat changes to boot.
- Galaxy Angel II: The final installment, Eigou Kaiki no Toki, the Rune Angel Wing discover a nanomachine organism in Femto while investigating about the Will, who is named "Cookie" by Nano-Nano. In Nano's route, Cookie grows from infant into a toddler after absorbing Nano's and Kazuya's DNA, essentially becoming their daughter. The after-credits image also shows that Nano herself has decided to adopt a more adult form of herself to properly take care of Cookie.
- Deconstructed in the Sonic the Hedgehog animation There's Something About Amy by Mashed. Rather than using magic or science to age up her body, Amy Rose lets Tails perform surgery on her to help her goal in becoming a couple with Sonic. As a result, Amy now has a grown-up body, but the reconstruction is obvious, with scarred and bandaged limbs. Amy also feels pain from the surgery and is trying her best to ignore it, having deluded herself into thinking she's become Sonic's ideal woman.
- Happens twice in a loudly lampshaded manner in PvP with Francis and Marcy, the first time with some Fourth Wall Breaking and the second revealing questionable rules of ageing for the webcomic's world. Technically, they should have already been at that age anyway, but rather than draw them aging in a natural manner from strip to strip, the artist opted to update them all in one shot. It also has something to do with Brent's prediction of when Francis would lose his virginity way back when the comic was still comedic.
- In The Inexplicable Adventures of Bob!, Molly, Galatea, and Djali are species that age from babyhood to vague teenagerdom in the span of one month.
- Done repeatedly and then reversed in The Wotch to Evan/Lily. It's not actually relevant to the plot a lot of the time, but it has been used for a few story lines.
- One of the many effects of the Timey-Wimey Ball in Enjuhneer is that characters stay the same age for an entire year, then suddenly change in a manner comparative to levelling up. This can cause drastic effects, or can be as simple as suddenly acquiring a pair of White Gloves with no idea where they came from.
- A rather odd version of this happens in Wapsi Square when Shelly, an apparently mostly normal human running around with three golems capable of destroying the world, a body controlled by a coven of demons, a god of alcohol, the atlantian mad scientist who created the golems, and the teleporting woman who controls the golems is suddenly aged up by 80,000 years and revealed to be an immortal and incredibly powerful sphinx... just so she can stay within shouting distance of the massive power levels of the other main characters of the comic. What makes it odd is that she was already a fully mature human woman in her twenties, but she still Aged Up by three and a half orders of magnitude.
- Kubera:
- Sura age like this as a general rule. They advance in stages, going from first stage (infants) straight to second stage (young children) after a few years. After that, they can spend hundreds of years at second stage, trying to find out what exactly is required for them to advance to third stage, since it's different for everyone. Once they figure it out, the change is virtually instantaneous, and suddenly they're teenagers. The last two stages work the same way.
- A very dangerous murder spell works like this. Leez is afflicted with it, and twelve hours after it is first cast, suddenly finds herself waking up after a nap, having gone from a sixteen year old Butter Face gonk to a beautiful young woman in her early-twenties. She loves her new form, and has no idea why the spell is a bad thing...until she's told that she'll die in twelve hours. The age-up is the cause of this, not a side effect. Every mortal has a set time when they will die (though they can die sooner due to accidents and so on). The spell brings your body to twelve hours before that appointed time. Though the effect can be reversed (and is, in Leez's case), it doesn't change their appointed time of death.
- In Bruno the Bandit Delorus, after becoming a fame vampire, turned into a five- or six-year-old in one shot when her mother literally took away her childhood and commanded her to "Grow up."
- Lion-O from ThunderCats, due to stasis failure.
- Enzo and AndrAIa from ReBoot age from children into adults while trapped inside a game due to time flowing faster there.
- Then the writers missed the young Enzo. So they made a duplicate from a back-up/archived copy. Since everyone is really a computer program, this makes some sense.
- Sari from Transformers: Animated discovers she's some sort of Mechanical Lifeform in the third season premier and tries using her AllSpark Key to "upgrade" herself. Besides giving her some new powers, this changes her body from a young child to a teenager.
- Professor Farnsworth had his crew go out and get "chronotons" for the purpose of doing this to a team of super-mutant babies in Futurama.
- At the end of the second season of Adventure Time, Princess Bubblegum is reverted to age 13 as a consequence of her recreation after being possessed by The Lich. In the third season episode "Too Young", she has to age back to 18 in order to take back the Candy Kingdom from Lemongrab. She tells Finn that she always had the means to age up, but was having too much fun being a child again.
- In "Jake the Dad", Jake and Lady's offspring were born, then became old enough to take care of themselves, going back to the status quo with Jake living with Finn again.
- Happens to Lloyd in Ninjago at the end of the episode "Child's Play" as a result of using Tomorrow's Tea to turn the Grundle back into bones. This physically ages him from a kid into a young teen, prompting the final battle with his father to draw closer. Curiously, Word of God says that he is still a child mentally, though certain events afterwards have caused him to mature at a quicker pace.
- In the My Little Pony: Friendship Is Magic episode "Secret of My Excess", excessive greed causes Spike (a baby dragon) to grow into a huge adult dragon, losing his mind in the process. When he finally manages to snap out of it, he returns to his young form again. (Equestrian dragons sneer at your conservation of mass.)
- For the first three seasons of Avengers Assemble, The Falcon was a teenaged version of himself. However, season 4 opened with the Avengers being scattered through time and space and unlike the others, when The Wasp and The Vision found Sam in a bad future, he'd aged into an adult and traded his classic appearance for one akin to his Ultimate and MCU ones.
- Kaeloo: In one episode Kaeloo finds out that Stumpy, who is ten, acts like a Kiddie Kid because his family stopped celebrating his birthday ever since he was five, which leaves him mentally stuck at the age of five. Kaeloo holds a "multibirthday" party to make up for the remaining five years, and since magic exists in Smileyland this somehow ages him up to the proper age. Unfortunately, the other guests at the party are excited to see the magic in action and keep celebrating more birthdays until Stumpy is aged up into a 30-year-old man. He's back to normal by the next episode.