A/N: I don't own Frozen or RotG. Enjoy!

A hushed giggle sounded from a fancily decorated door with a purple snowflake theme. On the other side of the constantly locked barrier...

The rather large room was covered in a soft white blanket of snow. The walls were obscured by smooth blue ice, too perfect to have been made naturally. Chunks of jagged solid water, still flawless, dotted the entire room. All of the furniture (the canopy bed, the many unneeded chairs, bookshelves, etc) were moved to cover the window, so nobody could see the surreal environment of the elder princess' home.

Another giggle burst forth from an 11 year old child with loose platinum blonde hair. Blue eyes twinkled with joy, despite her obvious isolation. Gentle winds of cool snow emerged from her extended hands as she ran around in unrestricted exhilaration, cyan dress dragged and billowed in the powdered ice crystals.

To any 'sane' adult peeking into the pale-skinned's room, they would think she was insane/crazy. No kid who played by themselves could ever be as happy as somebody with company, right?

Right. Thing was, Elsa wasn't really alone. Adults - nay, non-believers - couldn't see her only friend. They would think she was playing with her imaginary friend.

"Jack! Jack! Catch me!"

"Oomph!" A teenaged boy struggled to hold the sudden deadweight and catch his breath at the same time. The two were similar in appearances, but 'Jack' wasn't as regal looking; pure-white hair flopping in every direction, a dirty, frosted blue sweater, and the casual (bad-boy) way he held himself were only a few reasons why.

A frosted, gnarled shepherd's staff leaned against the wall, in easy reach of Jack if he ever so chose.

Oh, sorry, still wondering about Jack? His full name: Jack Frost. Familiar? Good.

Jack spun around in shock, eyes wide and mouth open in a perfect O. Clumps of snowball remains fell innocently from his shoulder. A smirk easily slid into place as he carefully, meticulously, formed a projectile by blowing into his palm. Soon, a hard-packed ball was being tossed in his hand. Elsa squealed in happy fear, knowing how good his aim was, and even if he hadn't, he could always use magic to help.

"You're done for, kid."

One hour later, two exhausted kids (technically one kid and one adolescent) lay panting on the ground. Two forts, one for each, sat on opposite sides of the room, one impressively made (by hand), the other... Not so much. Ice and snow trashed the battlefield.

"So, Elsa. Remind me again why you've self-imposed a lifetime of imprisonment?"

An emotionless mask snapped up on the girl. Instinctive. "'Cuz... I'm Anna's older sister. The only one close to her age who looks out for her. I have to protect her. The only way to do that... Is to stay away."

The Guardian of Fun sat up fast, agitatedly pacing back and forth while twirling his staff. "But you're getting better at controlling it!" It being her powers. He held up a pale hand to stop the usual, "Because you're not in any danger." The usual argument. Instead,

"Why would you care? You're dead!"

Small hands covered her mouth in mortification. He had told her how he'd died; entrusted her with this info. And she betrayed him. She could see the many emotional changes he was going through. Disbelief, shock, anger, resignation. "Wait, no no no, that's not what I meant!" But Jack was already gone.

Elsa ran to the glass and collapsed sobbing when she saw him riding the wind away, away from her.

In a different room, a strawberry blonde identical to Elsa lay flat on her stomach on her bed, thinking hard as was her wont for the past... several years. Devising more and more ridiculous ways to break into her sister's prison, and to get her to play again.

"You'll get old before you're 20." Golden eyes stared at the girl from the shadows, no body, no head, attached. Yet, a tall figure coalesced from the dark corner, and a man stepped out. With slicked back black hair, grey skin, and a pitch black robe, he was the perfect image of a dark villain. But not evil. If he was evil, he would have stolen Anna a long time ago.

He was Pitch Black. The Boogeyman, the bane of the Guardians.

"Yeah? I'll be 20 before Elsa even looks at me at this rate!" Anna didn't spare a glance for Pitch, she was too busy smothering her face into the pillow. "Oh! I know! I'll get a suit of armor and charge in like a knight! She'll just have to play with me then!"

"Oh please, that's crazy. You don't even fit them. Just let me scare - I meant talk - to her."

"No!"

"Why not?"

"I think we both know why."

"Fine," an uncharacteristic pout spread across his face. "Anything new?" He held up his hands in supplication when the 8 year old finally got up to glare at him.

She chucked her pillow at him, which Pitch easily dodged. "Besides thinking of breaking into Elsa's room? No."

"You need to get a life."

"Can't. The gates. Are. Closed." Every day, they got to this topic at some point.

"Sneak out." The way Pitch said it, it seemed like it wasn't a big deal. To him, it probably wasn't. Anna always attempted to sneak in, why couldn't she sneak out?

The child looked like she was having an epiphany. Sneak out? It was brilliant! The execution... Not so much. "How? They never open the gates, stuff always get delivered into the castle grounds."

He was nonchalantly examining his fingernails now. "Simple. The shadows." By now, the moon had risen, a waning crescent. There would be no danger to him by MiM. Without further ado, Pitch allowed the shadows to swallow them both.

Anna's scream caught halfway out of her mouth, her heart thumping madly in her stomach. It seemed to last an eternity and a second at the same time. Her eyes bathed in the darkness, it was oddly chilling and comforting simultaneously. The Boogeyman stood beside her, gracefully stepping out of the blackness when it unceremoniously spat them out. The ginger fell to her knees.

"Tada. On the other side of the gates. Don't you dare start singing again." He was oblivious to the child's discomfort.

"I didn't mean... Ugh... Now... Ahhh," she panted. Anna recovered her breath soon enough. "Where are we going?"

Pitch studied her in puzzlement. Kids are so durable nowadays. "You're not scared? At all? I just kidnapped you, and all you ask is where're we going?" She were always too trusting. Indeed, now she was scrutinizing him in confusion. Not like she knew what that meant, but still.

"Why? Should I ask you to lock me back into the fancified dungeon that is my home? Now, where are we going?"

She was spending too much time with him if she was starting to make up words. Then again, maybe everyone did it at one point. "The forest."

"Alright."

Anna nodded and sprinted through the town surrounding the palace, staying as quiet as possible so nobody woke up and questioned her presence. Pitch just stayed in her shadow. Before long, they were at the large expanse of wilderness. Together, they slipped inside.

Anna unbridled was a frankly scary scene. She ran around and screamed like a banshee, climbed trees like a monkey, and scared small animals like the Boogeyman. All the while, her... Guardian... examined the fallen leaves and kept wolves away. They both stopped when they realized something was wrong.

It was cold. Wind blew around them, nipping at both of their noses. Frost was forming on the leaves around them. Not possible in the all-year summer haven that was Arendelle. The only one who was able to do this... Was Jack. And speak of the winter devil, here comes the mighty Prince of Winter. "Anna... We need to go. Now."

"Not so fast, Pitch!" Jack aimed his staff at his nemesis as he landed. "Let the girl go."

'The girl' clung to the dark man fearfully. Fear of the sprite. "Wh-who's that?"

"Jack Frost," he spat. He quickly allowed a Nightmare to form and forced Anna on. The horse automatically knew where to go and ran off. Pitch's favourite believer looked back one last time before the two disappeared from sight. Now that that was over with...

A small horde of Nightmares appeared, backing up their King. He leisurely sauntered up to Jack with mock concern after managing to knock the shepherd's staff out of a tight grip. He took advantage of their closeness to study his enemy's glaring eyes. Jokul seemed upset, hurt, and looking for a fight. "What's wrong," he deadpanned, snapping his fingers and allowing his dark creations to dissolve.

The teen startled, stumbling back into a tree, cowering away from the towering Boogeyman. "What? Nothing's wrong, I'm fine, how are you?" he laughed nervously.

Pitch sighed and leaned against another tree. "Just fine," he drawled, "although I can't say the same for you. He held up the gnarled stick to prove his point. "Now what happened?"

Pale hands ran through silver-sheen hair. "It's just... Elsa doesn't like me anymore! I apparently don't care about her isolation, despite the- Are you okay?

The grey-skinned man's brow was furrowed in intense thought. "Elsa. You don't mean the scared blonde who hasn't come out of her room for years, do you?"

"I do. How?"

"Boogeyman," he said in a clipped tone. "She's Anna's sister?"

"Yeah. Wait. Wasn't that...?" Jack blinked. One) He was speaking to Pitch Black in a semi-normal conversation. Two) Why was Anna friends with him?

He hesitated. "...Yes." Pitch didn't let him continue, spinning around with a flourish and vanishing into the night. Jack looked up at the moon.

"Is he really our enemy?"

A/N: So I've been thinking of a crossover for some time. Then my sister and I started talking about imaginary friends. Then this came up. R&R!