Children Are Special

"At that time Jesus exclaimed: "I give praise to you, Father, Lord of heaven and earth, for although you have hidden these things from the wise and the learned you have revealed them to little ones."

- Matthew 11:25

Often in fiction, the "special nature" of children will be utilised to explain why only they are capable of certain things. Only children can see fairies, demons, angels or the monster under the bed. Only children are capable of accessing the dream world. Only children are capable of certain talents or abilities. Only children are immune to the killer virus that's rampaging across the planet, etc. This is often a companion to Growing Up Sucks.

Children Are Special, no doubt due to their innocence and naïveté, their purity of heart, or something along those lines. This is trope which has been utilised all over the place for centuries. It possibly has its origins in old folklore and legends.

Supertrope to Children Are Innocent, Only Fatal to Adults and Invisible to Adults. In some cases, a subtrope of Glamour Failure. Contrast to Enfante Terrible.

Anime

 * Serial Experiments Lain has a bizarre subversion of this, with a scientist harnessing the ESP of thousands upon thousands of children in an attempt to digitise reality. The children didn't get the better part of that deal.
 * Transformers: Cybertron: When the parents offered to accompany their children into space to do battle with the Deceptions, it was explained that only the open minds and hearts of children could really comprehend what was going on out there, and that however much the parents wanted to believe in their own ability to understand the situation, only the children really could.

Film

 * In The Polar Express, only children (and only children who Believe, mind you) can hear Santa's bells. When they stop believing or turn into an "adult," they stop hearing the bells, except for those few lucky enough to actually see the North Pole. The protagonist still hears the bells when he's an adult because he actually has the experience to remember while other children just have the memory of the belief. More likely it's an exception to the rule, while still suiting this trope.

Folklore

 * Child sacrifices are common in many mythologies (and fictional interpretations of), and the purity of the child may be a deciding factor. Creatures such the Unicorn were rumoured to be approachable only by young (usually female) virgins who were, naturally, often children. And in ceremonial magick, a child or virgin adult was employed for divination work, especially scrying.

Literature

 * Chronicles of Narnia: Susan becomes too "sophisticated" and "grown-up" for such childish things as Narnia. Peter, who is older, doesn't lose his "childish" belief. Because of that, Susan never returns to Narnia, even in the end; Peter does, even though he's an adult.
 * Stephen King's novels often make a point about how children are better suited to dealing with the supernatural - they can accept it easier than most adults, due to a grown-up's mind being set in the ways about the nature of the 'real world'. Additionally, the titular monster of IT claims that only children can use the power of belief and Chud to stop it. The grown-up protagonists prove it wrong, but this may be to do with the fact that they had defeated it once as children already.
 * Cliff McNish
 * The Doomspell Trilogy: by the end of the second book, the "magic" inside of every child the world over had been unleashed giving most of them the ability to do just about anything, from fly, to change their hair colour, to kill people. Each child possessed a varying level of ability, but they all had it, more or less. This magic faded away as the child aged into adulthood.
 * Silver Sequence: children all over the world develop powers and change physically (often in some borderline Body Horror ways) in response to a fast-approaching alien threat.
 * Older Than Feudalism: In The Bible, Jesus tells the disciples not to turn away a group of parents hoping to have their children blessed by him because one cannot enter to the kingdom of heaven without being like a child... whatever that's supposed to mean.
 * Ender's Game is probably somewhat of a subversion. If a child's trained from a young age in Battle School, then they can become as good a commander as an adult, and can learn how to understand the Buggers-- . Which means that yes, children have the trait needed, but it's not necessarily a positive one.
 * In Acorna's Quest by Anne McCaffery and Margaret Ball, children can see the true form of the Linyaari, even when they are projecting something completely different. It's stated that children of any species are psychically undeveloped.
 * The little girls in Zilpha Keatley Snyder's The Changeling believe that "babies are born knowing all sorts of magic stuff, until they start thinking separately and forget everything." They rely on a baby sister as a kind of oracle/talisman. Snyder's subsequent Green-Sky fantasy trilogy builds on this idea, then inverts it: infants have ESP but the fact that powers are lost with maturity isn't a cute bit of Wordsworthian nostalgia but a symptom of what's literally wrecking the culture.
 * Dealt with very practically in Clifford Simak's No World Of Their Own. Other-dimensional creatures are visible only to children, until someone invents corrective lenses for adults.
 * A somewhat twisted version in the Knight and Rogue Series. In general humans are the only species without magic, only having weak abilities like vague senses, but there are some children who can use magic. Children only, becuase only simple children can use magic, and between their powers and their mentail impairments and whatever other health problems come with they never last to adulthood.
 * In Devon Monk's Dead Iron, LeFel abducted a four-year-old to act as his dreamer.

Live Action TV

 * Quantum Leap: Children, animals, and the mentally handicapped are the only ones who can see Al. Explained as Alpha brain waves or something which alters as one grows up, unless one is an animal or mentally handicapped.
 * Horiffically subverted in Torchwood: Children of Earth. The alien invasion has come to collect ten percent of earth's children

Tabletop Games

 * The New World of Darkness sourcebook Innocents uses this trope quite a bit.
 * In Pokethullu only children are capable of dealing with the thullu without going completely insane or running away in terror.
 * In Monsters and Other Childish Things only children have monsters... with the exception of an incredibly creepy old man who didn't grow up. It's implied this is because monsters, being immortal, don't really change, and tend to be more childish than the kid in the first place, so the kid outgrows them.

Video Games

 * The Legend of Zelda the Minish Cap: Only children can see the Minish, and even then, that's not much use as they're incredibly tiny.

Webcomics

 * Scott Christian Sava's Dreamland Chronicles: only children can enter the world of dreams. The random appearance and disappearance of human children from their world is taken in stride by the inhabitants, and people begin to appear there less and less as they age. This is a familiar trope across many fictions dealing with a Dream Land.

Western Animation

 * In The Fairly Oddparents, children are the only humans who get fairy godparents.
 * In Winx Club, only children can see the Pixies in Bloom's world.