Disclaimer: Harry Potter belongs to J. K. Rowling. Frozen belongs to Disney. The cover's photo belongs to a Nico Benedickt, from Unsplash.

Chapter I: The Welcoming Hat

When, on her eleventh birthday, the crown princess of Arendelle walked into the throne room to discover an elderly man standing in front of her parents, she hadn't thought much of it. Although he was dressing in strange robes and wearing the longest beard Elsa had ever seen in her life, a great number of eccentric characters often came to see the King and Queen. As they had been speaking in English, the girl first regarded him as an ambassador.

However, when the man, Albus Dumbledore, turned to look at her for the first time, Elsa knew right away that she had been wrong. There was something in his eyes—something magical—and, trying to decipher it, the girl barely listened to his very first words to her, much to her parents' exasperation. "You are a witch," he repeated, much to the princess' astonishment, and proceeded to tell her about how she got a place in his school of magic, located in Scotland.

Elsa was, perhaps, the only muggle-born in Hogwarts at that time who had tried to reject the invitation. All the stories she had heard from other students told her astonishment was a rather common feeling at the discovery of a magical world just within their grasp, but it was always followed by wonder and joy. The princess of Arendelle, however, felt only shame and disgust; ever since the accident, three years prior, she had decided she wants nothing to do with magic.

If it weren't her parents, she would have never set her feet on the castle. Upset about her response and eager to have someone teaching her how to control her magic, they were adamant about her enrollment in Hogwarts. It was the answer to their prays, her father had told her. They were lucky that Dumbledore had taken notice on her, considering that Arendelle was far from the school's territory and foreign students were rare enough in there even among magical families.

Helpless against her parents' demand, Elsa had seen no option but to do as she was told. The girl didn't doubt that she would soon be back, however. Her parents' advisors—clueless about her magic and the nature of Hogwarts—were outraged by the notion of sending their young crown princess to a foreign school when they had very good schools and tutors within the kingdom. They were still to find a law that allowed them to interfere with Elsa's education in that particular situation, but the girl had no doubt they would soon figure out a way to bring her back.

"Why are you so against it?" Her mother asked her once with a frown; neither she nor the king could understand the reason Elsa wasn't excited about meeting boys and girls who were just as magical as she was. The girl, however, just shrugged. The thought of nurturing the exact thing that had her little sister, the person she loved more than life itself, almost killed was incomprehensible to her; she would much rather eradicate it.

Elsa couldn't understand why her parents were in favor of the study of magic when it had brought them nothing but sorrow. She still remembered the deep concern and sorrow in her mother's eyes as the royal family stood in front of the trolls, praying that they would be able to help Anna. The crown princess had never seen her bubbly five-year-old sister so still, frail, cold. No, the only knowledge Elsa wished to acquire at that point was how to get rid of her magic.

Anna. As the girl entered the grand entrance doors of the castle, it was all she could think about. She would love it here. Because the younger princess had adored magic from the day she was born. Elsa was only three years old by then, but she would never forget the wonder in her sister's eyes when she looked at the tiny snowflakes the girl had created just for her.

Yes, Anna would have loved studying Hogwarts. She would have appreciated every single one of Elsa's school books; not only the content in each chapter, but its entire craft. The dim light of the candles—because there seemed to be no place for electricity in the school—wouldn't have been intimidating at all, she would have thought of them as an invitation to an adventure. And the moving and talking paintings— if Anna was indeed an art enthusiast, like her tutor and her parents had told her, Elsa was sure she would be beyond words if she set her eyes on them.

While the other students seemed to grow unease and excited as they approached the teachers' table and stopped in front of a singing hat, Elsa was deep in her thoughts. She had to stop herself from giggling at the thought of Anna's reaction to the great hall, a place that screamed "magic" more than anything she had ever done in her life. Perhaps, the girl mused, she could send a letter to her sister telling her everything about Hogwarts. Perhaps—

"Kyrre, Elsa!" Startled, the crown princess looked at the stern-looking teacher she thought to be called Professor McGonagall. Elsa could sense in the tone of her voice that this hadn't been the first time the woman had called her, much to her embarrassment. Being a good multitasker, there weren't many occasions she had been caught not paying attention to a teacher.

The problem, and she knew it would come back to bite her again, was the name. Technically, she had been named Elsa Iduna Solveig Kyrre, but people had always called her either "your royal highness", "princess" or simply "Elsa". Therefore, even though her father had warned her that would be the name they would be using, the girl couldn't help but being irresponsible when referred to as Miss Elsa Kyrre. No matter how much she rehearsed it in her head, it would be a problem.

However, as the hat covered her eyes, shielding her from the view of the giggling faces of the other students, such thoughts vanished immediately. "Ah! What do we have here?"A voice—the hat's voice—whispered in her head. This time, was she the only one listening? "Quite an interesting mind, I see—" A dreadful thought popped into Elsa's mind: if the hat could read her mind, it would be able to see and tellothers about her mistake, her shame. The girl gulped, vær så snill, ikke fortell noen— jeg mener— please, don't tell anyone! God, please! "A worrier, huh?"

A pause followed as the hat seemed to contemplate, and Elsa felt the cold slipping from the tip of her fingers to the cloth of her white gloves. She swallowed hard once again, trying to control her magic. Please, don't tell— "a hat never tells," the girl's erratic thoughts were suddenly interrupted by the amused response; "now, where should I put you?" Once again, it seemed to be contemplating her. "What a mind! And in all these centuries— I have rarely seen such raw talent! In Ravenclaw, you shall find your equals. However— such extreme beliefs for a young mind. No, I believe—"

Another pause. Elsa wondered how long has it passed since the hat was first placed in her head. It mustn't be too long, otherwise, people would become agitated. Wouldn't they? "I can see wit, strong loyalty and the burning desire to succeed. Perhaps— you might find kinship in Slytherin." For a reason, the hat didn't seem too sure, and the girl had a hint on the true reason. While she didn't want to attend Hogwarts, the crown princess knew better than going with no knowledge of the place. The chapter about the house of Slytherin in "Hogwarts, a History" told her about its founder's firm belief that no muggle-born should be taught magic in Hogwarts. The hat would know better than placing one there, right?

"That leaves us— HUFFLEPUFF!" The last word came out louder than the previous and Elsa took a few seconds to realize the other students were clapping, which meant she had been sorted. Hufflepuff— a warm feeling filled her chest at the remembrance of an excerpt in "Hogwarts, a History" about the house.

"Hufflepuff is, perhaps, the most misunderstood of the Hogwarts houses in the modern age. Designed by the Welsh witch Helga Hufflepuff during the earliest days of the school's foundation, the house acquired the reputation of forming weak and dull wizards and witches because of its overall approval of students regarding their background or personal skills.

Helga Hufflepuff valued fairness and loyalty, which she aspired to teach the new witches or wizards. Her lessons have been passed from generation to generation of Hufflepuff students, strong enough to create a tradition of acceptance, honesty, kindness, and communion within the house. To this day, it has produced the lowest number of dark wizards and witches of all the four houses of Hogwarts."

Elsa didn't feel particularly accepting or kind at that moment, but the judgment of something—or someone—that could see the darkest corners of her mind filled her with joy like she hadn't experienced in many years. Besides, if Hufflepuff didn't bring up as many dark witches and wizards as the other houses, perhaps there was hope for her magic, for herself. Perhaps she wasn't so bad, after all.

With a smile of relief on her lips, Elsa carefully took off the hat and placed it back on the stool she had been sitting. After a glance through the hall, the girl walked towards the closest table on her left, where the applauds were coming from. For once, being at Hogwarts didn't seem too bad; too far to hurt her sister and surrounded by people who knew about her magic, things might turn out fine.

Author's Note:

Hello, y'all!

I will be honest here, this is not my main project at the moment. I have spent the past three months writing a major Elsanna fanfiction, which I will only start publishing when I have it entirely written since I have a lot of trouble keeping a posting schedule. A friend of mine asked me to write a Frozen/Harry Potter AU, though, and I had so much fun doing it that I decided to make it a multi-chapter thing.

Although I am not sure where I want to go just yet, there are a few things I have set in the stone: 1) this is a character-driven story focused on Elsa learning how to accept and control her magic; 2) while this is not a relationship-driven story, I will explore the relationship between Elsa and several other characters from the Harry Potter universe and the Frozen movies; 3) the romantic endgame will be Elsa/Tonks (hence the tags); 4) I couldn't find any confirmation on the date that Nymphadora Tonks and Charlie Weasley started Hogwarts, so, for the purpose of this fic, I am establishing that it happened in 1984.

Finally, neither English nor Norwegian is my native language. So, the text might not be the very best, but I am trying. If you spot any mistakes, though, feel free to point them out to me so I can fix them.

Anyway, sorry for the long note.

I hope to see you again in the next chapter o/