The old forests of Sweden are beautiful in daylight.
Towering pines whispered in the wind. Moss glowed emerald beneath ancient stones. Crystal lakes reflected skies so blue they looked endless.
But everyone in the village of Björkdal knew one rule:
**Never stay in the forest after sunset.**
Especially if you were a child.
The elders spoke of trolls—not the foolish creatures from fairy tales, but ancient things older than churches, older than kings, older even than the forests themselves.
"They don't eat children," Grandma Ingrid would whisper.
"They steal them."
No one believed her anymore.
Except Grandma herself.
---
Nine-year-old Elias certainly didn't.
He ignored every warning his parents gave him.
He bullied smaller children.
He stole sweets from the village shop.
He threw stones at birds for fun.
Worst of all, he laughed whenever Grandma Ingrid warned him about the trolls.
"They're just stories."
She looked at him with tired eyes.
"They only come for naughty children."
Elias rolled his eyes.
"Good."
---
One autumn evening, Elias wandered into the forest after dark.
He wanted to prove everyone wrong.
The woods became strangely quiet.
No birds.
No wind.
No insects.
Then...
**Knock...**
A sound echoed from somewhere deep between the trees.
Like stone striking wood.
**Knock... Knock...**
He frowned.
"Who's there?"
Silence.
Then another knock.
Closer.
---
He followed it.
The deeper he walked, the stranger the forest became.
The trees bent in impossible directions.
Roots twisted like giant fingers.
The moss felt warm beneath his boots.
Then he saw them.
Tiny footprints.
Bare feet.
They led toward a massive boulder covered in moss.
The knocking stopped.
---
A voice spoke behind him.
"Found you."
Elias spun around.
Nothing.
Then...
Something stepped out from behind a tree.
It was about as tall as a child.
Its skin looked like cracked gray stone.
Its nose was enormous.
Its yellow eyes reflected no light.
Its mouth stretched impossibly wide.
It smiled.
Behind it...
Dozens more emerged.
Watching.
Smiling.
---
They didn't run.
They simply stood there.
One reached into a sack and pulled out...
A child.
No.
Not a human child.
A troll child.
It looked almost human.
Almost.
Its fingers were too long.
Its smile had far too many teeth.
Its eyes never blinked.
It stared at Elias with unsettling curiosity.
Then it copied his voice perfectly.
"I'm Elias."
The other trolls giggled.
---
The largest troll stepped forward.
Its beard dragged across the ground.
Mushrooms grew from its shoulders.
"We take the bad ones."
Elias laughed nervously.
"You're not real."
The troll reached out.
Its icy finger touched his forehead.
Memories flooded his mind.
Hundreds of children.
Across centuries.
Taken.
Replaced.
Families never noticing.
The replacements learned.
Copied.
Smiled.
Ate.
Spoke.
But every full moon...
They returned to the forest.
To feed.
---
"I want to go home."
"You will."
The troll grinned.
"But not as you."
The troll child walked forward.
Its bones cracked.
Its face shifted.
Its nose shrank.
Its hair changed color.
Its skin softened.
Within seconds...
Elias was staring at himself.
Perfectly.
Even the tiny scar on his chin.
The copy smiled.
"Mother will be happy to see me."
---
The real Elias screamed.
The trolls laughed.
They carried him into the mountain beneath the boulder.
The stone sealed behind them.
The last thing he heard was his own voice calling from outside.
"I'm home!"
---
His parents noticed something strange.
Their son was suddenly...
Polite.
Helpful.
Never angry.
He apologized.
He cleaned his room.
He hugged them.
Everyone said he had finally matured.
Only Grandma Ingrid frowned.
One evening she asked him a simple question.
"What prayer did your grandfather teach you?"
The boy smiled.
"I don't remember."
She knew.
---
That night, she followed him.
At midnight he slipped silently into the forest.
He walked without a lantern.
Without hesitation.
As though something was calling him.
Grandma followed until she reached the old moss-covered boulder.
It opened by itself.
From inside came laughter.
Hundreds of childish voices.
Not human.
She peeked inside.
Her grandson stood among dozens of identical children.
Some looked Swedish.
Others looked centuries old.
Some still wore clothes from another age.
Around them stood towering trolls.
One enormous troll spoke.
"The exchange is complete."
The children answered together.
"In another generation..."
"...we take more."
---
Grandma fled.
She tried to warn the village.
No one believed her.
After all...
Elias was the sweetest boy anyone had ever met.
Years passed.
The troll child grew into a kind young man.
He married.
He had children.
Perfect children.
Until one misty autumn night, when the oldest turned nine.
The father smiled.
"Would you like to go for a walk in the forest?"
Far away, beneath the ancient mountain, the real Elias—still nine years old, never aging—heard another child begin to scream.
And somewhere in Sweden, when a difficult child suddenly becomes *too* well-behaved overnight, the oldest villagers still refuse to celebrate.
Instead, they quietly close every curtain, lock every door, and whisper a single terrified sentence:
**"The trolls have made another exchange."**