Changeling Fantasy

"I hate my parents. They're so mean and they never understand me. I'll bet they're not my real parents... one day my real parents will come save me. They might be royalty, or magical."
—Countless teenagers

A trope with its base in Rags to Royalty. It takes an Ordinary High School Student (or elementary school student) and whisks them off to meet their real family, whose lives are always more glamorous, dangerous, and full of adventure than the dull foster family the hero has been living with, and delighted to meet this stranger who happens to be a blood relative. This may involve going Down the Rabbit Hole if not hopping cities or countries.

Or, more rarely, they have been living with the unusual parents all along, who are pulling off an elaborate Masquerade to keep the truth from them until the time is right.

If the two families are not the same, the foster family is usually a cartoonishly abusive and unloving bunch. They tell the hero that they'll never amount to anything, and they had better not think about royalty or magic. Most shows won't even bother revisiting the foster family after the first episode, except (maybe) to have them show up as minor dupes of the Big Bad later. The plot has obvious appeal for any teen who has ever felt unloved. (Piling on the Glurge is optional.)

They may even have an Orphan's Plot Trinket to signify their heritage. Compare Cinderella Circumstances, where the main difference is that the heroine is always worse off and doesn't have to be switched, if the parent fell on hard times and remarried.

In both television and other media, this is an increasingly Subverted Trope. The most common subversion is for the adventures to be so dangerous that the hero decides I Just Want to Be Normal. The second most common is for the real family to be unpleasant people, possibly even the Big Bad.

Perhaps this is due to the greater acceptance of adoption today. It used to be extremely taboo and "shameful" to discover that one was adopted. Nowadays the Changeling Fantasy is evolving into dualism; with the main character having one foot in both worlds. Yes, they have a fantastic lineage; but it's their down-to-earth family that ultimately shaped their values.

Compare Escapist Character, Ascended Fanboy, Rags to Riches.

Often overlaps with Moses in the Bulrushes and/or Switched At Birth and very often I Just Want to Be Special.

Related to Door Step Baby aka Foundling, and Separated at Birth. Muggle Foster Parents is a specific subtrope.

You may be looking for the Darker and Edgier version known as Changeling Tale, which is the source of the name. A changeling is an elf/troll/gremlin/etc. baby that gets swapped for a human baby and ends up being raised by humans (or the baby is merely abducted and raised by elves). It's very common in medieval folklore. Examples of fairy abduction should go there, not here.

It's also a component of Hero's Journey, especially when a Farm Boy is involved.

Examples of Changeling Fantasy include:

Straight examples

Anime and Manga

The heroine of The Twelve Kingdoms.
- Subverted with Yuka (in the anime, at least), who is convinced this is the case for her. It's not.
In the manga version of Mermaid Melody Pichi Pichi Pitch, Lucia has been living with Nikora all along, but hasn't been told she's a princess.
- Kaito also just happens to be part of the ancient Panthalassa race.
Martian Successor Nadesico: Ruri Hoshino, after having lived the bulk of her life as a lab experiment, discovers her real family - who are the Cloudcuckoolander royalty of a Theme Park-based Ruritania. She ultimately decides that her biological family is completely irrelevant to her life, and returns to the crew of the Nadesico.
Hanaukyo Maid Tai. At the beginning of the series Taro discovers that he belongs to a fabulously wealthy and powerful family.

Comic Books

Amethyst, Princess of Gemworld.
Superman values both his Kryptonian heritage and his foster-parents. However, this perception varies from medium to medium or even from writer to writer. His origin doesn't fit this trope very well either way; in the Silver Age, he always knew he was Kryptonian due to super memory of his early years on Krypton. In the Post-Crisis take, Superman didn't know he was Kryptonian until adulthood but it was evident long before then that he wasn't human (or at least, a normal human). In the latter version, he tends to cling to his human values and upbringing (especially in the Smallville series).
In Spy Boy, Alex wishes at the beginning for one to escape his crappy school life until he realize how brutal the espionage world really is.

Fan Works

99% of Self-Insert Fics.
Also pretty popular in Harry Potter fics.

Film

Luke Skywalker.
Pan's Labyrinth. Although Ofelia rather loves her human mother, and seems to have loved her long-dead father, it's presented as an unambiguously better thing to live in the underworld full of magic. Mostly because dad is dead, mom is very weak-willed, and new stepdad is a zealous fascist. Unlike most examples, Guillermo del Toro actually takes into account the implications of such a statement.
In Wanted, the main character is bored and dissatisfied with his mundane life until he finds out that his father was a bad-ass super assassin and he's inherited his powers.
Who's Your Daddy?, about a boy who inherits his father's (played by Wayne Newton) porn empire.
The premise of The Princess Diaries. Subverted at first because Mia resists the idea of going from socially awkward, pathless New York high schooler to ruler of a foreign country for most of the movie.

Literature

The Harry Potter series, of course. Then again, both of Harry's parents are dead—and most of the other parental figures he acquires either abuse or betray him, or are killed. And the Dursleys who raised him get slightly sympathetic by the end. (Well, his aunt and cousin do anyways. The uncle stays a Jerkass.)
This is the entire point of the new book series The 39 Clues in which two children find themselves to be heirs to the most powerful family on earth.
Kaye from Holly Black's Modern Faerie Tales is a literal changeling, swapped as an infant for a human baby. She later meets the child she was switched with, who has aged only a few years in the Seelie Court.
Oliver Twist by Charles Dickens is a low-rent version, where the missing parent turns out to be middle-class—but given that the title character was thoroughly poverty-stricken, it's a major leg up.
In Eva Ibbotson's The Star of Kazan, the main character, Annika, a foundling, despite having a loving family, endlessly dreams of the rich woman who will sweep into the house one day and tearfully ask for the baby she abandoned in a church years ago. Of course, when such a woman really does appear, Annika finds that she does not like life as a noblewoman's daughter and, at the end of the book, is perfectly willing to accept that the woman is not her real mother, as expressed by her jumping off of a boat to get away from her.
In The Horse And His Boy, Shasta turns out, in the end, to be a prince. An unusual example in that The Reveal comes after the climax; he goes through the entire book believing himself to be a commoner. He does overhear at the beginning, though, that the man he thought was his father really found and adopted him, and he briefly fantasizes that he might be anyone, even royalty. Then he has to run away and seems to forget all about it.
- Shasta is also an unusual example in that, although he's happy enough to learn that King Lune and Prince Corin are his father and brother, he's considerably less thrilled to discover that this means he'll have to be king someday. (His brother Corin is delighted to be shoved off the throne. "Princes have all the fun!")
In Andre Norton's Scarface, at the end, Captain Cheap reveals that he has his Revenge by Proxy: Justin Blade is the son of his old enemy Sir Robert Scarlett and will hang as a Pirate. Whereupon he learns that Justin's case had been remanded on new evidence even before they learned this.
- In The Jargoon Pard, Kethan was Switched At Birth to ensure his mother had a son. Contrived Coincidence ensures he meets his birth parents and the girl they are raised, and he ends up with them. (This combines with Happily Adopted, though—the girl stays with them, too.)
Christopher Paolini's Eragon, which features the titular Farm Boy becoming a Dragon Rider and leaving the village where he grew up with his adoptive parents. He knew they were not his real parents from the start, however, and didn't find out until much later on who his real father was.
In the sixth book of L. J. Smith's Nightworld series, Soulmate, Hannah learns that she is an olld soul, and emotionally related to Thierry.
In James Thurber's The 13 Clocks, at the end, the Wicked Duke reveals that the Princess Saralinda is not his niece; he had kidnapped her.
Percy from Percy Jackson and The Olympians book series.
- Percy and about ninety percent of his friends.
- Finding out the other parent is often a bad thing. For starters some parents were kind of absent. One can understand not telling a kid since they'd brag (Hey, it didn't turn out so well for poor Phaeton!) but when they need to know and they aren't there...well... Things are improving in the new saga, apparently. (demigods were claimed instantly; and they actually talk to their children)
The title character of Zilpha Keatley Snyder's book The Changeling spends almost the entire book trying to convince herself and a friend that she is just that.
Deconstructed in The Princess Diaries novels. A princess's duties and responsibilities are tough, and poor Mia didn't even want them in the first place.
In the Tunnels series, Will learns that he was adopted and that his real parents are inhabitants of the Colony, a secret civilization Beneath the Earth. Subverted, however, when his biological parents turn out to be just as unpleasant as his adoptive ones.
The Temeraire series has an odd take on this. While the titular dragon is considered a valued and unique piece of ordinance in the British Aerial Corps; when he goes to China he finds out that A) dragons in general are treated as large citizens/subjects with wings rather than talking warbeasts and B) he is by rights part of the Imperial Household. While he does return to Britain it is with plans for reform on his mind.
In Animorphs, Tobias admits at one point that as a child, he had liked to imagine that his absentee parents had some sort of amazing lives/reason for abandoning him. In fact, his father was an alien transformed into a human who left to fight a war, while his mother was unable to care for him due to medical problems.
In Septimus Heap, Jenna, the only daughter of the Heap family, after ten years of living within the Heap family is revealed to be the daughter of the Queen and heir of the Castle. She had been adopted by the Heaps after the Queen was shot and Marcia Overstrand only barely managed to rescue Jenna from the Assassin sent out to kill them.
In Gene Stratton Porter's Her Father's Daughter, Linda knows her father is her father, but she seriously doubts that her sister is her sister. When she turns eighteen, she learns that her mother Died In Childbirth, and when her father remarried, he and his new wife had agreed to raise their children like actual sisters. (But it couldn't be hidden because it was In the Blood.)
The story of the Ugly Duckling.
In Gene Stratton Porter's Freckles, it's inverted; the hero is convinced that his birth is as lowly as it seems, and the other characters set out to persuade him otherwise.

Live Action TV

Connor, from Angel. The son of two vampires, he was abducted as a baby and raised in a Hell Dimension by a fanatical demon hunter, eventually returning to Earth as a teenager. His memories are later replaced with an elaborate web of fake ones, allowing him to live an ordinary teenage life, at least until a demon tied to his past comes looking for him.
- Thankfully, he gets to keep his elaborate web of fake memories, so as not to go Ax Crazy.
Odo in Star Trek: Deep Space Nine discovered that he was actually a member of a dangerous race of shapeshifters who were also the leaders of The Dominion, the Big Bad of the series. Bonus points here, because his species was (due to their powers) actually called "changelings". This was presumably an intentional joke.
- Subverted by the fact that it's evident from the beginning that Odo is from another species (its more the revelation of what place his species occupy in the Dominion that comes as the shock) and by the fact that Odo's adoptive culture is friendlier then his home culture.
- The more regular explanation for the name "Changeling" is the Founders' ability to impersonate humanoids and use this for infiltration - that's what the Changelings did in legends (pretended to be human and corrupted others).
This was arch-villain Sylar's Start of Darkness on Heroes. It was further played with in Volume 3, with two wealthy Evil Geniuses each gaining his loyalty by claiming he really was adopted, and that they were his real parents. When he found out that it was all complete BS, he killed one and almost killed the other.
- In Volume 4 they have Sylar's Changeling Fantasy actually turn out to be true, in that he really was adopted, and his biological father turns out to have been a powerful supervillain...but it's subverted as Sylar finds him a "big disappointment" due to all the Villain Decay his dad had undergone, courtesy of cancer, apparent poverty, and sheer boredom with life. Its implied as well that he never really did much with his abilities anyway other than kill people for their power and Sylars mom, and was just a self-centered Jerkass who doesn't give a crap about his son and never did. When he finds out Sylar has a Healing Factor and is effectively immortal, he tries to kill him for it and get a new lease on life. Except Sylar overpowers him without much effort.
Tin Man: DG is a waitress and part-time college student with little direction in life. She's plagued by a vague, unsettling feeling she doesn't belong in Kansas and strange, recurring dreams. Turns out she's princess of the O.Z., descended from and named for her ancestor Dorothy Gale, and the people she thinks are her parents are a pair of robots.

Myth And Legend

King Arthur is raised by Sir Ector. Though treated well, he's considered of lower rank than Ector's biological family, who have no idea of his true identity.

Toys

Takua from Bionicle was always thought to be a Fire-type Matoran, however, it is later revealed that he was a Matoran of Light, removed from his homeland and brainwashed into forgetting his past for his own protection.

Video Games

Cecil in Final Fantasy IV is adopted by the King of Baron. His mother was a normal human, of whom blissfully little is said, his dad was an alien from the moon. In a subversion. we later learn that his adoptive father-figure, the King of Baron, was not a human either, but the Eidolon Odin.
- A similar tune with Terra in Final Fantasy VI except her dad was an Esper. She also wasn't so much adopted as "brainwashed" and mind controlled. For someone who spent most of her life that way, she takes it surprisingly well.
The hero in Dragon Quest VIII was actually brainwashed so that he wouldn't remember that he's actually half Dragovian.
- Inverted in a cruel way with Angelo and Marcello, though...
World of Warcraft has Thrall, who eventually became the Warchief of the Horde and was the son of a shaman.
Played very darkly in the King's Quest universe with both Alexander and Edgar. Expanded Universe material manages a partial Deconstruction by stating that Alexander doesn't even think of himself as a prince. Inwardly, he still thinks of himself as "Gwydion," Mannanan's former slave and signs his name as Alexander-Gwydion.

Webcomics

In Girl Genius Agatha doesn't know that she's the last in the line of a dynasty of Mad Scientists, or that her adoptive parents are their iconic assistants Punch and Judy (although she did know they were Frankenstein-esque "constructs"). She preferred her normal life. In a subversion of sorts, her mother is a Complete Monster, and she has tried to possess Agatha, practically succeeding.
- Also Gilgamesh, who believed himself to be an orphan taken into the Baron's care, and spent the first years of his life at the bottom of the pecking order established by the other kids on Castle Wulfenbach. He used to imagine who his parents might have been (maybe he was a lost Heterodyne!). After a couple of red herrings, he finally found out he was the heir to the Wulfenbach empire, raised in secret for his own protection. The revelation (and the need to keep it secret) leads to a wedge between him and his friends, especially his former best friend Tarvis.

Web Original

Whateley Universe example: introverted Bill Wilson has no idea that he's about to manifest as a mutant, or that his parents are not only mutants themselves, but they work for the CIA as mutant superheroes. Or that his older brother and younger brother are actually mutants themselves (they don't know this yet either). This family is about to have a lot of 'splainin' to do.
Both tropes are explored and played tragically straight in the short story "Changelings and Fairfolk" on Strange Stories About Sad people.

Western Animation

In a nearly forgotten cartoon series called Wildfire, an 'ordinary American cowgirl' named Sara turns out to be the princess of a realm from which she was removed in infancy for her own safety. Later in the series she discovers that the man she lives with as her 'adopted' father is her true father the Prince, exiled for his own safety and brainwashed to forget his heritage, presumably to keep him from trying to return.
Don Bluth's Anastasia is a long-lost, amnesiac Russian princess. (With an interesting twist: prior to her discovery of her true heritage, she plans to pretend she's the princess and takes appropriate lessons in history and protocol. Then she's in for a surprise when the Big Bad, who swore to destroy the entire royal family, comes after her...)

Subversions, Inversions, and Parodies