Do you ever think that a loved one is acting off, and maybe they appear a little different, but you can't quite put your finger on how?

You might not immediately suspect a changeling, but some people would.

A changeling is a monster, but in human guise.

Stories of trolls, fairies, elves, witches, and demons taking humans and replacing them with imposters circulate across the globe.

The legend of the changeling is uniquely connected to the history of German, Scandinavian, and Celtic cultures.

They've even made their way into real world courtrooms.

[adventurous music] I'm Dr. Emily Zarka, and this is "Monstrum."

In the 13th century text "De Universo," French theologian William of Auvergne introduces the idea of demons who were substituted for infants.

These thin, colicky, and insatiably hungry babies would stick around for a few years to nurse, then vanish.

William makes a point that these creatures are not real, but instead an idea that illustrates the devil's existence.

His contemporary, Jacques de Vitry, however, believed these creatures to be real, and attempted to use these stories as proof that the devil had a physical malignant presence on Earth.

It's from these Christian roots that the lore of the changeling grew.

Numerous 15th century theological texts, including the 1486 "Malleus Maleficarum," claimed the devil himself was responsible for switching children with demons.

In 1566, Martin Luther claimed to encounter a changeling child, a 12-year-old boy appearing unremarkable, but with an insatiable appetite.

When something evil happened, the child would laugh.

Anything good would be met with tears.

Luther recommended killing the changed child.

Changelings found their way into fiction of the time as well.

In William Shakespeare's "A Midsummer Night's Dream," powerful fairies fight over who gets to keep a boy stolen by the fairy queen Titania.

He's referred to as "the changeling boy."

Some of the growing changeling lore might have been a way for parents to justify their children's unusual behavior or severe illness.

Some psychologists argue that attributing children's odd behavior to supernatural causes allowed parents to justify their cruel response toward a disabled, sick, or unruly child, since, in their minds, a changeling was a monster and not their own child.

In the 16th century, the term "changeling" might have referred to a person who is fickle or changed their opinion regularly rather than a supernatural swap.

And beginning in the 1600s, changeling was a derogatory term for people with intellectual disabilities, separate from the "monster" concept.

Changeling lore expanded to include older children and even adults, who were usually replaced by an older fairy.

Changelings take on the identity of their human counterpart, but something is usually off.

They may look emaciated despite their voracious appetite, or wrinkled with old age.

[changeling cackles] Their behavior is peculiar.

They're irritable and unpredictable.

In Celtic tradition, changelings have squeaky voices.

A substitute child might have mobility issues or suffer from a failure to thrive, or conversely, will be unusually intelligent and precocious.

People relied on several ways to expose a changeling.

You could perform an unusual task in the kitchen, something so bizarre that an ancient supernatural being would be compelled to call it out and reveal their advanced intelligence.

Placing a changeling on hot coals or fire or shoving a hot poker down their throat would bring back the abducted human.

Or, if the changeling was beaten, the original human might reappear.

Suspected changelings might be left exposed to severe weather elements or abandoned outside overnight in a place where Fae folk were said to reside.

Water could work, too.

Changelings left on a shoreline or dipped in the water would cause their Fae brethren to take them back.

The supernatural kin would feel compelled to save their changeling from human abuse and return the mortal.

Part of the changeling narrative is a warning about negligence.

As long as parents remain vigilant, their child will never be swapped for a changeling.

All of this stuff about fairies and trolls and detecting the existence of changelings became folklore as it spread from Christian theology to popular lexicon.

What was originally philosophical and theological claims were later attributed to folk belief to make them seem more authentic and commonplace, and, frankly, scarier.

In the 1726 "Isle of Man," English author George Waldron wrote about seeing a real changeling.

He describes a five-year-old boy who could not move or speak, and while very malnourished, had a beautiful face.

He would appear bathed even in the absence of his parents, suggesting he had greater abilities than his appearance would suggest.

Changelings boom in the 1800s, in real life accounts and in fictional literature.

It was something many people believed were real.

A child alleged to be a changeling was displayed in London pubs.

The nine-year-old was mute, short for their age, had a small face and no teeth, but had an insatiable appetite.

An 1826, a woman went on trial for drowning a four-year-old boy that could not stand, walk, or speak.

She believed he was a changeling that, if bathed in the river three times, would cause the Fae to bring back the real boy.

But she held him underwater too long, and he drowned.

Changelings eventually made their way into children's books, and adult fiction, like Samuel Lover, W. B. Yeats, and Sheridan Le Fanu used the archetype of a fairy kidnapped child in their work.

Popular written folklore collections continued to include the changeling, often emphasizing the violent steps that return the human from the supernatural realm.

Take this example, from Yeats' "Irish Fairy and Folk Tales" in 1888.

A mother becomes distraught when her once beautiful blue-eyed boy changes into a constantly crying skeletal child.

Even though she knew the boy was a changeling, she couldn't find the nerve to hurt it.

Then she hears of a nonviolent way to reveal the fairy's true nature-- put the empty shells of a dozen eggs in boiling water, an unusual and inexplicable act the changeling would have to comment on.

As the mother does this, the baby speaks in an old man's voice.

"What are you doing, Mammy?"

Just as she's about to douse the creature with the boiling water, she recognizes that her child has been returned to the cradle.

People in the Victorian Age were kind of obsessed with changelings.

Many stories included changelings, and parents would use them to keep children well-behaved.

Occultists attributed the changeling legend to instances of reincarnation or possession.

Some medical professionals even speculated that changeling lore was based on a primitive English race, who stole healthy children in an effort to advance their own genetics.

Artists chose them as their subjects, and newspapers reported on changeling accusations, like John Trevelyan, who had his little boy starved and beaten, or a female victim in 1845 who was hung in a basket over a kitchen fire.

Multiple children were poisoned with foxglove, a plant believed to make fairies disappear.

One British newspaper in 1884 reported two women arrested for child mistreatment after they placed a child who did not have use of his limbs on a hot shovel, believing it would reveal its true nature.

All these horrors in the name of changelings.

Not all reported changelings were children.

Adults were accused, as well.

In 1895, the British Medical Journal reported on a burned corpse found in a shallow grave.

The female victim, Bridget Cleary, had been tortured and killed under suspicion of being a changeling.

Her family and neighbors all believed her to be an imposter.

Eleven people in total were charged with her death.

In court, testimony from her neighbors revealed she had some form of mental illness.

Her husband had consulted a fairy doctor, who allegedly gave the directions on how to return the real Bridget.

This included force feeding her, threatening her with a hot poker, and holding her over the kitchen fire.

Eventually, her husband doused her in oil and set her on fire.

In a twist that truly seems made up, the charges were dropped from "willful murder" to the lesser charge of manslaughter because they were operating under the assumption that she was an evil fairy, that somehow justified their actions.

Likely the first time changelings were equated with intellectual disability occurred in the mid 19th century in a German collection of folk tales.

The book combines fragments of earlier changeling stories, and adds that the substitute child fails to develop mentally.

A few years later, in 1860, a book of German superstition reaffirmed the idea that changelings and mental disability were somehow connected.

The author makes the first scientific connection to inherited disability, suggesting that changelings are stories about what he referred to as "cretinism."

Other medical theories were proposed, as well-- everything from severe malnutrition to intestinal disease.

In the mid 20th century, when the first autism diagnosis occurred, people began to look back and suggest neurodevelopmental disorders as a theory for changeling accusations.

If that's true, then changeling legends where they weren't abused could be read as a form of acceptance.

The parents recognized and accepted the special needs of a child instead of trying to change them.

As science and medicine tried to explain these creatures, other fictional genres incorporated the changeling into their narratives.

In 1956's "Invasion of the Body Snatchers," extraterrestrials altered their forms to duplicate humans.

"Star Trek's" 1967 episode, "The Changeling," prescribes the title to an entirely different kind of non-human entity, a robot probe.

In 1976 "The Omen," an adopted newborn replaces one lost in childbirth, but the parents would learn the supposed newborn is in fact the Antichrist.

Even today, changeling lore thrives.

Some of my personal favorites include "Double Walker," which uses the changeling idea to examine pregnancy loss and grief.

"The Neighbors" uses the changeling to explore identity and teen angst.

Then there's Victor LaValle's "The Changeling," which goes back to the Scandinavian troll tradition in some truly unsettling ways.

There's something that still sticks about changelings, even for me.

Even though my rational mind knew fairies wouldn't come and take my newborn, I still made my family swear up and down that my baby could not leave the room without one of them present.

I couldn't shake the fear someone would swap my child for another, either accidentally or intentionally.

If you ask me, changelings are about an inherent fear of imposters.

It might have been theologians who first wrote about changelings, but it has endured because of its successful jump to popular culture.

Plus, they asked the question: "Can we ever truly know someone's real nature?"

Numerous 15th century theological texts, including the 1958... Whoa.

Okay, wow.

Claimed the devil himself was... Was responsible.

Is it "Titiana"?

-(crew) I think it's Titania.

-Titania.

I need to read that again.