Disclaimer: Frozen and its characters are owned by Disney.

Promise

Against the midnight blackness, as the invisible winds howled and invisible raindrops descended from the heavens, a fork of lightning lit up the dark clouds for the briefest of moments, and a fearsome thunder cracked across the sky. It's ear-splitting BOOM jolting a young red-headed Princess frightfully from her sleep. The girl let out the smallest of gasps as she sat upright, pulling the covers up to her chin as the sound of fat raindrops pelting the window panes filled the bedroom.

Another flash of lightning illuminated the room, producing a stark contrast between light and darkness, and with another gasp, the young four-year-old hastily lay back down, determined to muffle out the thunder that was yet come as well as the rest of the storm. She was halfway under her pillow when a soft sniffle caught her ear.

Carefully and slowly, the Princess sat back up, listening. Sure enough, after a short moment, another soft whimper was heard. Someone was crying! Immediately, her eyes fell onto the bed just across the dark room.

"Elsa?" she whispered.

Much to her horrified amazement, her sister moaned softly, "No…Anna… I didn't mean to…"

"Elsa?" Anna was off her bed and waddling across the room as fast as her legs could carry her, the soft padding of her feet on the polished wooden floor drowned out by the heavy rainfall outside.

Upon reaching the side of her sister's bed, she jumped, trying to catch the side of the bed in order to haul herself up; an action that proved to be quite difficult due to her height.

"Elsa!" she whispered once more, hoping that hearing the sound of her voice would make her beloved older sibling stop hurting.

"I'm sorry, Anna…" the words were heavy and so full of sorrow it scared the little girl. Why was her sister apologizing like that? Why was she so sad?

An expression of hard determination set itself upon Anna's soft, round features then. Whatever was making her sister sad, she was not going to let it continue. Thus, with an industrial grunt and all her might, she leapt up once more, this time managing to catch the bedside and quickly crawled up.

"Elsa!" Anna scooted to where her sister lay curled up under her blanket, her back facing the approaching younger Princess. Once close enough, Anna reached out and began shaking the crowned Princess' shoulder, "Elsa, it's me, Anna!"

"Anna…?" Elsa's voice was dripping with sleep as she lifted her head from her pillow, slightly dazed from her abrupt awakening, yet it still held a slight tone of worry as she looked around the room, allowing her eyes to adjust to the blackness that engulfed the space in front of her. Seeing that there was nothing out of the ordinary, she turned to look behind her, and almost immediately Elsa's drowsy gaze fell upon the worried face of Anna. When teal met blue, the older princess' eyes widened ever so slightly, the remnants of sleep quickly dissolving from her irises and, in a blink of an eye, embraced her younger sibling.

"Oh, Anna! You're safe!"

A slightly dumbfounded expression plastered itself on the red-headed princess' face then. She had not seen that coming. However, Anna returned the embrace, comforting her sister being her first priority at this very moment. "Elsa," She whispered, "what's wrong?"

"Oh, it's nothing…" the older princess mumbled, "Just a bad dream, that's all."

"A bad dream?" Anna gasped and held on just a little bit tighter.

"It's okay, Anna. I'm fine now." Elsa said as she parted from their hug in order to look Anna in the eye, giving a smile and hoping that she made it look reassuring enough for her sister. She hated making her worry.

"What was your dream about?"

Elsa considered the question, then frowned a bit, "I… I can't really remember, but… I think it had something to do with my magic."

"Your magic?" the younger Princess' voice held surprise, "But Elsa, your magic is good. Why would you have a bad dream about it?"

"I'm not sure." Elsa shook her head, "But anyways, it was just a silly dream. We should get back to sleep. Go back to bed, Anna. Okay?" she let another smile grace her lips, showing that everything was alright now. Yet her sister's eyes still held worry.

Anna looked down and took hold of one of Elsa's hands, "You're really okay now, Elsa?"

"Of course I am, Anna." The crown Princess pulled her sister into another affectionate hug, "Don't worry anymore, okay?"

"Okay." Anna returned Elsa's smile and slid off the bed.

Another lightning flashed then, casting a wicked light across the floor and making every little shadow in the room all the more eerier. In the next moment the light faded and the shadows expanded, spreading out and swallowing everything. The thunder boomed just outside the window and suddenly, the short journey across the room seemed not as easy as it was before to the little Princess.

"Umm… Elsa?" Anna asked in a small voice.

"Yes?" Said Princess poked her head out from the side of her bed.

"Can I sleep with you instead?"

Elsa merely chuckled, extending a hand towards Anna, who in turn took hold of it, a wide grin on her face as her sister pulled her up onto the bed and beside her, tucking her in.

"Goodnight, Anna." Elsa yawned as she slid back down under the covers, letting her head rest on her pillow.

"Good night, Elsa." Anna replied as she lay down as well, facing her sister, the storm outside seemingly some distance away now; small and insignificant. Both sisters lay still as logs, the only sound in the room being the pitter-patter of raindrops against glass. That is, until Anna cracked open an eyelid and raised her head slightly off the pillow.

"Elsa?" she asked tentatively, just in case her sister had already drifted off into slumber.

"Hmmm?"

"We'll always be best of friends, right? No matter what, we'll always be sisters?"

Elsa opened her eyes then, moving in just a little more closer so that their heads almost touched, all the while looking Anna straight in the eye and, wrapping an arm around Anna, gave her the most reassuring smile ever.

"Nobody and nothing can ever separate us, I promise."

A/N: Based heavily off comic book Fables issue #95. The sisterly fluff there was just so good.