A/N: As said in the description, this fanfic has evil!Elsa (or onion!Elsa, or concept!Elsa, whatever you want to call her), but she isn't evil since the beginning. Therefore, this story will be divided in three parts, with the first one being mostly fluffy and funny, the second one angsty and the third one angsty, violent and depressing. If you're okay with that, please continue reading :)

Book 1. Childhood.

Chapter 1: The new sister.

Three years Elsa – New born Anna.

Elsa was a three years old girl, but she wasn't just a common child, no; she was a princess, more even, she was the first born of the King and Queen of Arendelle, heir to the throne, and as such, there were things expected from her, like staying in her room without complaining when her father ordered her so, even if she could hear the terrifying screams of her mother resonating trough the castle and all she wanted was to search someone's comfort. But no; she was alone in her cold dark room just hugging tightly her pillow, imagining it was her mother instead.

She knew her little brother or sister would be arriving soon, but she didn't understand why did the queen had to go through so much pain or why she couldn't be there when her sibling came to the world. She just knew that once he or she was with her everything would be alright, that she'd finally have someone to play with, someone who understood her, with who she could count all her life and that she would never feel alone again. Now, however, the emptiness of her room and the hall outside was overwhelming.

Finally, after what felt like an eternity for the young girl, the screams ceased. She waited for someone to come for her, to bring her to meet the baby that, no doubt, had already been born, but she was left there by her own until she couldn't keep her eyes open anymore and she drifted to sleep.

"Papa, it's been three weeks!" The child whined. "Why can't I see her yet?"

"Elsa, what have I told you about patience?" The king answered, kneeling in front of her and looking at her eyes. Elsa just frowned and continued pouting stubbornly. Her father sighed. "Your sister is very young and fragile" He tried to reason. "You could hurt her… accidentally." He hesitated at the last word, but the princess didn't notice.

"I promise I'll be careful. Pleeeasee?" She requested with hopeful eyes.

"You will see her. Eventually." The king said smiling and rubbing her hair.

"When?"

"When she's older."

"How older?"

"About your age."

About my age? Does it means I have to wait three years? That's a lifetime!

"But…"

"No buts. A princess should be calm and patient, and follow every rule."

Elsa was about to protest again, but as soon as she opened her mouth, her father's face became sterner, and she knew what that meant; speaking now would mean punishment, maybe even a week without chocolate! She couldn't risk it, so instead she kept her feelings at bay and answered with gritted teeth:

"Yes, father."

The man nodded and stood up, walking away as he was followed by the angry and disappointed glare of the princess.

As soon as he was out of the room, Elsa sighed and sat again on her bed, trying to play with her toys, but she soon realized she couldn't concentrate. She wondered why she wasn't allowed to see the new born, was it like that in all families, or only between royals? How did her sister looked like? Was she similar at her? Would she have powers too? Oh… right, her powers. She was born with magic over ice and snow, and no one knew why, but she loved it, even if her parents insisted her to not ever use her powers. They never gave her a reason though, so she just played freely with her cold magic when no one was looking, even if she sometimes got in trouble for it. That was one reason because of which she wanted a little sister; to share the fun of her powers with someone who could be as thrilled for them as she was.

Those were her thoughts when her stomach grumbled and she decided to go to the kitchen to see if she could steal some snack, but just as she was passing through a particular door in the desert hallway where her own room was, she heard a weird sound, like crying, but high pitched, kind of resembling one cat's meows, but clearly human at the same time. She recognized it as her sister's crying, and that was definitely her sister's room, but, unlike previous times, there was no one around to shoo her away. Curiosity won over hunger and the girl found herself approaching cautiously to the door after making sure that, indeed, no one was around, reaching up to turn the doorknob and getting in.

It was a pink room, with nothing but two chairs, a little wardrobe and a pink crib with a small bulge wrapped in blankets from where the high pitched cries were coming. Elsa's first instinct was to cover her ears and run away from the unpleasant noise, but she kept strong and started walking towards the baby.

When she climbed atop one chair and looked down inside the crib, she found a round little face with big teal eyes and a few strands of reddish hair at the top of her small head. The first thing she thought was that the newborn was certainly ugly, and that the way she was screaming and the fact she didn't have any teeth certainly didn't make her look any better. Was this really her new sister? The one she would be going to spend the rest of her life with? Her future play mate? She certainly didn't seem so, but Elsa just shrugged at the thought; she'd have to be enough, after all, anything was better than being alone.

Elsa wanted to introduce herself to the baby, but she knew she couldn't as long as she kept crying her lungs out, so she thought about how to make her stop. The crib was designed to move, so the girl thought it may be a good idea to swing it, to see if her sister could calm down that way, but it only worsened the cries. Maybe she just needed something to distract herself? Perhaps a few snowflakes swirling over her head would shut her up? Elsa certainly didn't have anything to loose, and so she make her magic, instantly appearing perfect dancing snowflakes from thin air, which emitted a faint glow that promptly caught the younger girl's attention.

Well she hasn't shut up, but at least she seems to be interested in my magic.

After a few moments, the baby finally stopped crying, to instead stare at the snowflakes with wide eyes, eventually using her clumsy hands to try and grab one. Elsa giggled at her fruitless efforts and tried to move all the snowflakes from left to right, enjoying the way her sister's eyes followed them closely. It was the first time her powers had a good reception, and it made her truly happy, even if the approval came from a newborn. She then made the exercise of disappearing all the snowflakes except one and making it float to the baby's little nose, which caused her to cross her eyes to see it, something that Elsa found cute and funny and it made her feel warmth in her heart. Maybe her new sibling was a lot more than it appeared at first sight. She was sure they'd get alone.

In that moment, though, Elsa was so distracted that she didn't notice when Anna (She now remembered her name) took her finger with those tiny hands of hers and stuck it into her mouth.

"Eeeeeewwww!" Elsa exclaimed upon sensing the saliva and pulled out her finger, which caused the baby to cry again. The older girl looked anxiously to the door, making sure nobody had been alerted of her presence due to her sibling's cries, and when she saw no one, she placed her finger again on the infant's little mouth without thinking twice about it. The horrible noise that was coming from that little mouth just seconds before, instantly died and Elsa saw the content face of her sister, clearly enjoying sucking at her finger.

"You're weird." Elsa said. "If father saw you he'd say that's something a princess wouldn't do… wait, has he told you that you're a princess? Well, if not, I'm telling you now: Congratulations! You're a princess, just like me… well, not quite like me; I'm the heir, whatever that means. But I'm also a princess. I'm your older sister, Elsa, and I hope we could be friends. I promise to be the best sister ever, and to always play with you. We'll have lots of fun, you'll see, and we'll snake into the kitchens to grab some chocolate. I hope you like chocolate, because it's my favorite food… Papa says princesses don't roam around the hallways at night to find food though. Actually papa is always giving orders, saying what a princess should and shouldn't do, and mamma is the same, and the nobles, even the staff! Everyone expects a lot from you when you're a princess." Elsa sighed, but then she looked at her sister's innocent gaze and couldn't help but smile, promising herself that she'd take care of her, that she'd never let anyone tell her what to do. "But you and me…" She beamed mischievously. "We know better."

In that moment, Anna's eyes started to shut down and the grip she had around Elsa's finger began to lose until she released it completely and Elsa could safely pull it out of her moth to wipe it on the blankets. Once she was sure the baby girl was sleeping, she placed a tender kiss on her temple, almost falling into the crib in the process, and said:

"Goodbye Anna. I'll come visit soon, I promise."

In that moment, the door opened and the queen stepped in, looking at her with an expression that can only be described as surprise with hints of terror.

"Elsa!" She gasped. "What are you doing here?"

"Shhh." Elsa said placing a finger on her lips. "You'll wake her up."

"But… how…?" The woman was out of words for a second.

"She was crying, so I came here and calmed her down." She explained as if it were the most natural thing in the world. "I know you didn't want me to meet her yet, but I can take care of her, see?" The girl said grinning.

Her mother approached to the crib and took Anna in her arms. After checking if she was still warm, breathing and didn't have any injuries, she was able to relax and softly place the younger princess back on her crib. She then turned to the older.

"How did you know how to calm her down?"

"I honestly didn't have any idea." Elsa giggled. "But as I was trying to figure it out, she took my finger into her mouth and eventually fell asleep. It was kind of gross." She made a face.

"Elsa." Her mother said adopting a more serious tone. "I'm not amused with you breaking the rules. We clearly told you not to come here under any circumstances until we said so." Elsa hung down her head in anticipation; she was going to be punished. "However, I understand that you wanted to see your sister." Elsa's head shot up in the fraction of a second. "And maybe it wasn't the best decision to try and keep you two apart, after all you're siblings, future rulers of Arendelle, and if you're together, you'll be stronger."

"A-are you saying you're not punishing me?"

"No, you're still going a week without dessert." Elsa pouted. "But I'll talk to your father and you'll get to see your sister from time to time. Always as one of us is on watch, of course."

"Thank you!" The girl screamed as she ran and hugged her mother, who hesitated only a moment before returning the embrace. "I'm glad I won't have to be alone anymore."

The queen's heart broke at her words, feeling guilty about it, so she lifted her up in her arms and said, looking at her daughter's beautiful blue eyes:

"I know that we're not always with you, but you won't be alone never again once your sister has grown up." Elsa nodded happily. "Now, what about we go to your room and have a little tea party?"

"But tea parties are not fun!" She complained. "Why don't we better play seek and hide?"

"Elsa, that's not a princess game." The queen scolded.

"Oh… s-sorry." Elsa casted down her eyes, disappointed but not wanting to ruin the opportunity to spend time with her mother. "Tea party sounds good." She faked an smile for the queen, who nodded approvingly.

"Okay, little princess, let's go."