Author's Notes: This story takes place shortly after Frozen Fever and sometimes during Season 8 of the new Doctor Who series, and will contain spoilers for season 7.
It is not necessary to have read my previous story "Unless there is children crying" to enjoy it (but of course it's better if you read it ;) ).

Elsa pulled up the next letter from her stack and sighed as she recognised the seal on the envelope. Weselton again. She quickly opened it and briefly glanced through it. Once again, the duke was "politely" asking the Queen of Arendelle to reconsider her decision to sever all trades, and so on.

Elsa sighed again, and struggled for a few seconds to suppress a sneeze. The fever that had affected her on Anna's birthday was now a memory, but she remained on alert for other symptoms and tried to avoid sneezing as much as possible, even though her sneezes had apparently ceased to create Olaf's baby brothers.

The queen picked up a blank sheet of paper and dipped her quill in the ink bottle. As she began wording the usual rebuttal, her mind wandered once more over the events that had happened more than a year ago. Not for the first time, Elsa wondered how things would have turned out if she had acted differently on the day of her coronation and managed to avoid revealing her powers. For one thing, she would not have to write every month or so to Weselton that ordering to kill her was not a "deplorable misunderstanding" as he worded it. But then again she would probably still be frightened and alone, unable to control her powers and avoiding Anna, who would still be desperate enough to fall in the clutches of those like Hans.

I should have avoided to strike Anna when we were little instead, Elsa mused as she interrupted her writing to dip her quill in ink. She had thought about that countless times during her childhood, how moving her hand a mere inch in either direction would have spared Anna, sometimes even dreaming she had actually done it only to wake up in her frozen and lonely bedroom.

It had actually been one of her subjects of reflection during those long hours spent alone locked in her room. Would have that been enough? Would the accident have happened later, when her powers were greater, putting her sister's life even more at risk? Or would have she been able to better control them instead?

She had occasionally passed the time thinking about it, wondering about the best way to prevent herself from hurting Anna. She had even dreamt of being able to go back to that fateful day, and warn herself, but this simple fantasy brought more questions. How would she be able to convince her younger, carefree self that she was right? Would it not instead cause the accident? And what would it be like to talk with a younger version of oneself?

Now in retrospect, Elsa was somewhat grateful that this fantasy never came to pass. If she had managed to prevent this accident, it was very likely that Anna would have never met Kristoff and Olaf would probably never have existed either. That was the thing when dreaming about changing past events: you could not choose which ones would still happen afterwards. And sometimes, even the worst moments led to something wonderful.

Take this unwelcome fever during Anna's birthday. Elsa would have given anything for the illness to begin only a day after; she would have been able to sleep it off quietly in her room and offer her sister the birthday she deserved. And yet… those hours spent in bed with Anna caring for her were now a cherished memory, and Anna kept assuring her it had been the highlight of her birthday.

Then there was this memory of the day where she had hugged Anna on the frozen fjord, mere seconds after having believed her lost forever. That day had been the stuff of nightmares, of those you would be ready to sell your soul for them never to have happened. But she still remembered the sheer, unadulterated joy she had felt at hugging someone for the first time in thirteen years, and to have this person be her beloved sister. It had reminded her of the first time she had taken Anna in her arms when she was a baby and herself a little girl. The memory regularly came back to her as one she would cherish forever now, even though she was a bit ashamed of herself at remembering so fondly something that had been so close to a tragedy.

So maybe it was better that the past happened the way it did. It was not as if she could do anything about it anyway.

Elsa signed her letter and slumped in her chair. She had been working all morning and was really in need of a break, but she wanted to finish this stack of letters. It was amazing how work tended to pile up when you were sick, especially when you insisted on not offloading it to your secretaries and advisers. She reached for the next letter in her stack.

"Elsa!"

The shout, although muffled through the door, echoed in the corridor outside her study. It was accompanied, she heard now, by the frantic footsteps of someone running. Elsa could not prevent a little smile from forming on her lips as she recognised her sister's voice. Maybe she would have to take this break after all. She certainly would not fight much if Anna came to suggest one of her latest ideas.

"Elsa! Come quick!"

Anna half crashed into the door as she opened. She remained panting a few seconds, leaning on it, as Elsa stood up and walked to her. Finally she managed to speak between two gasps.

"Elsa! The box! The blue box! It's back!"

Elsa's eyes went wide. She knew what her sister was talking about. The mysterious box had appeared in the castle a few times during their childhood, and the people inside – a strange man called the Doctor, and two different women – had brought some emotional support to them at a time when they needed it. They had seen the box one last time, shortly after Elsa had managed to thaw the winter she had set on the country, but the lone man inside had been very different, even though he had insisted he was also called the Doctor.

The sisters had exchanged their stories about the mysterious box and its occupants, and had wondered time and again about who they could have been, and how this box could disappear and reappear. Anna held that the man was a wizard, and the women with him his apprentices, with the other man being one of his successor. Elsa had been trying to find a more rational explanation, but had been hard pressed to find one, even though she entertained a few wild theories that she had not dared sharing even with her sister.

The box appearing in the castle was an opportunity to learn more about this it. It was not something to be missed anyway, and was certainly a good excuse to take a break from the stack of letters. Elsa rushed out of the study in the wake of Anna and followed her at a brisk pace to the courtyard.

The box was there, blue and incongruous in the large space, getting curious glances from the people walking around it. It looked exactly how Elsa remembered, which was like nothing she knew. She still did not understand what "Police public call box" was supposed to mean exactly, for a start.

The sisters gathered in front of the box, trying to catch their breath.

"Do you think we should knock?" asked Anna, looking at the door hesitantly.

"Why would you knock?"

Anna jumped back with a little cry of surprise, and Elsa had to steel herself to avoid doing the same.

A man had appeared in the door frame of the box, looking like neither of the men they had seen there. He was far older, with grey hair and a wrinkled face, and piercing blue eyes staring at them under bushy eyebrows.

"Um… hello Sir" Elsa said hesitantly. "We thought you were the Doctor."

"I am the Doctor" the man said curtly. "Why would you knock?"

"We wanted to… talk?" Anna ventured.

"Talk about what?"

Elsa took a deep breath.

"I'm sorry, Sir, but we had been visited by someone in a magically disappearing blue box just like yours, and we wanted to see him again. But it seems there is more than one person using this box and…"

"No", cut the man. "There is only me, and this is my box. My TARDIS." He looked at them intently for a few seconds. "Oh wait, are you supposed to be the Princesses of Arendelle?"

Both sisters looked at each other, then back at the man.

"Yes we are" Elsa said eventually. "I'm Queen Elsa, actually, and this is my sister…"

"How old are you now?" he asked, squinting at them. He pointed to Elsa. "Your hair is white, does it mean you are old?" He leaned forward. "No, wait, that's not white, that's platinum blonde… Your species does not get platinum blonde hair with age, does it? One of you could create ice, right? Was it you, with the freckles?" he asked, pointing to Anna. He frowned. "There was one with the ice and one with the snowmen. Aaand… the sky. Something about the sky." He looked at them impatiently. "So? Which one is which?"

Anna hesitantly raised a hand. "I'm the one with the snowmen, Sir. My sister does the ice thing. How did you know…"

"I told you. I am the Doctor. I already visited you three times. You saw me twice with a bow tie and once with sand shoes. Is that right?"

Both sisters looked at the man intently. Try as she might, Elsa could not see the slightest resemblance between this man and the tall man with the bow tie, even though her memories of him were a bit blurred with time, nor with the sad stranger she had last seen exit the blue box.

"There was someone else in the box" Anna said eventually. "She was called Amy. A very nice woman. Did she change her face as well?"

The man looked down.

"No" he said, in a suddenly sad voice. "Well, yes she probably did, eventually. But she's not with me now."

Elsa had been struggling with her memories.

"Clara" she said at least, remembering. "There was also a woman named Clara. That was ten years ago."

"Clara is with P.E. right now. Why she would want to spend so much time with a soldier, I would not know, but that's Clara for you. So, can we proceed now, or is there anyone else you want news from?" He turned brusquely to Anna. "Before you ask, the snowmen we built together have all melted by now. There is no need to ask me how they are doing."

"So… It was really you?"

The man sighed exasperatedly.

"Is it so hard for you to understand? Are there really only pudding brains on this planet?" He pointed an accusatory finger at Elsa. "You, Platinum, can create a thermodynamic inversion at the subatomic level, and you still have trouble grasping the concept of people changing faces? I'm the Doctor. The same Doctor who built snowmen with you, and the same one to whom you gave that little ice sculpture that took ages to melt. I simply changed. Now there was something I had to tell you and I will finally do it now."

The man drew a deep breath. He then spoke in a more subdued voice, like someone who has to perform an unpleasant task but will not back up from it.

"I was with your parents on the ship the day they died."

Both sisters let out a gasp. Elsa heard a familiar creaking and realised that ice was forming under her feet. The man went on, looking from one to another with a softer expression.

"The ship had been… contaminated by an alien consciousness. It would have spread to anything wooden on Earth. Oh, and it was homicidal too. I tried talking to it, but all it wanted was to kill sailors."

Elsa reached out and seized Anna's hand, who clasped it tightly. She was relieved to feel the ice at her feet receding.

"So we had to sink the ship. Your parents were very brave. They remained until the end to make sure it was destroyed. I could not save them. I'm... sorry, I think" the man added gravely.

Elsa tried to speak but realised her voice was not steady enough for that. Instead, she drew her sister against her.

"They told me to ask you to speak to each other. But I kept missing the right time. I can travel in time, you see. And it appears that you not speaking to your sister was a fixed point in time, and I could not change it. So I never managed to arrive before you actually did it by yourselves. There, that's done."

"Wait, what?"

The man sighed exasperatedly at Anna's exclamation.

"Fixed point in time. Something that can't be changed. I did not realise it at first because I was probably too busy trying to impress my companion. I used to do that."

"You can travel in time? With this box?"

"Yes. It's called the TARDIS." The man hesitated a second. "You can take a look inside if you want. But don't! Touch! Anything!"

Elsa tried to pull her sister back, but Anna was drawn to the box like a magnet. The man stepped aside to let her pass the door. Elsa watched worryingly her sister disappear into the strange box.

"It's all right", the man said. "She will be safe as long as she does not touch too many buttons. You don't want to see it?"

"There will hardly be enough room for both of us here", Elsa said dismissively, trying to look through the slightly ajar door at what her sister was doing inside the box.

"Oh, it's a bit more spacious than it looks."

The queen looked the man squarely in the eye.

"My sister is a bit quick to trust strangers."

The man looked at her uncomprehendingly.

"This includes strange men and their disappearing boxes."

"Ooh, you were talking about me, then? But I'm not a stranger! I built snowmen with her, some centuries ago, give or take. For me, at least. For her, this must have been… two, three decades? Or maybe just one. It's hard to keep track."

Elsa crossed her arms and cocked her head.

"But you are not this man."

"Yes I am. The packaging may change, but I remain the same person. With a better taste in clothing."

"But this man was nothing like you!" Elsa burst. "He was taller, much younger, and that was only a dozen years ago. Not to mention… somewhat nicer" she added pointedly.

The man looked at her intently.

"And you were a frightened little girl who shut herself in her room because she was terrified of not controlling her powers" he said eventually. "People change with time. It is simply a bit more obvious when it happens to me."

Elsa, taken aback, was looking for a retort when Anna slowly exited the box, walking backward. She stood for a few seconds some feet from the door, looking at it in awe, then ran in a circle around the box, stopped, peeked through the door, before rushing back in the other direction, repeating this routine a few times. Eventually she stopped and ran to Elsa.

"You've got to see this, Elsa" she shouted excitedly. "It's not a box on the inside!"

"What?"

The man smiled, not unkindly, and opened the door of the box wide. Elsa gazed with incomprehension at the sight before her.

"There is a whole room inside" Anna babbled without stopping to catch her breath. "There are a lots of lights all around, and some big desk in the middle, and corridors leading away, and strange knobs and switches everywhere, and this big column at the centre, and…"

Elsa slowly walked to the box. As she reached the door frame, she gazed at the face of the man who was standing on the side. His defiant expression was off-putting, but there was something in his piercing blue gaze that indeed reminded Elsa of the bow-tied man somehow.

"You keep saying you are the doctor. Doctor of what? Doctor who?"

"Just the Doctor."

"Do you heal people?"

"I try to help. Sometimes I don't fail too much."

Elsa looked intently at him one more time. She had noticed that her first impression of people were often the right ones. The Duke of Weselton had made her skin crawl when she had first been introduced to him. Hans had felt almost frightening, despite his polite smile, or maybe because of it. Kristoff had felt reassuring, although the fact that he had been rushing to Anna's side when she had first met him had probably influenced her judgement.

This man, this Doctor… felt dangerous, but kind at the same time. And very alone.

Elsa stepped into the box.

Anna had not lied. The cavernous room had no right to be in such a small space. And yet it was there, full of strange lights and sounds, extending in corridors beyond what she could see. Her sister was still babbling excitedly, running back and forth around her, pointing at everything and commenting on it.

The Doctor joined them, then stepped up near the big strange console that occupied the middle of the room.

"This is my time machine, the TARDIS. She can move in space and time."

Anna gently led her hand on the console.

"Hello, TARDIS" she said softly.

"Anna!" Elsa hissed softly, "you were told not to touch anything."

"I was just saying hello to it. It's polite."

"It's a machine! You don't speak to Kristoff's sled."

"Well I could" Anna said sulkily. "If he was not looking. Besides, this TARDIS is not a sled. It feels… not like a machine."

"Your sister is rather perceptive for a pudding-brain" the Doctor said dryly. "The TARDIS is actually a twelve-dimensional…"

A bell rang loudly, incongruous in the strange metallic space. The Doctor started.

"It was not me!" Anna cried, hastily removing her hands from the console while slowly turning crimson. "I did not touch any button!"

"No, it's not you" the Doctor scolded, running frantically around the console and hitting various switches. "There is a temporal alteration… oh no, no, no, don't do that, hold on…"

The floor shook as if they were on a ship in a storm. Elsa managed to keep her balance, but Anna crashed into her and both sisters went down, as another sound filled the room. It was the strange complaint, rising and falling, that they had associated with the arrival and departure of the box. The unseen bell rang another time.

"No!" the Doctor was shouting exasperatedly to the large cylinder that extended above the console. "I did not ask you to take off! I don't want to travel with them! I was only showing them the interior!" The bell rang another time. "And stop doing that! If there is a temporal anomaly, show me what it is instead of fleeing it!"

The whole room shook. Sparks flew from the walls and the console. Both sisters clung to each other as the floor rocked in various directions.

The Doctor was running around the console, frantically hitting switches and knobs. The bell rang again. Then the shaking subsided, as the groaning from the central column became more regular.

"There! It's stabilised" the Doctor shouted.

There was the almost musical chord that the girls had associated with the disappearance of the box. Silence fell again in the big room. Anna and Elsa scrambled to their feet.

"What happened, Doctor? Was it my fault?" Anna asked, brushing herself off, as Elsa noted with some satisfaction that there was only the slightest amount of frost on the floor where she had fallen.

"Maybe" the Doctor grunted, looking at various blinking panels on his console. "Something scared the TARDIS away when you entered. Now I'll have to reset the temporal coordinates but first, I must know where we are. I need to understand what scared her."

"Was that true? That you could travel in time and space."

"Yes, it is!" the Doctor said in exasperation, as he strode toward the door.

"So we could be… in another country?"

"Or planet" the Doctor said, yanking the door open.

A gust of cold wind hit his face as he stepped out, followed by the two sisters.

"Wow" Anna said in an awed voice.

The courtyard, full of the summer sun, had disappeared. They were now in a stone corridor. There was snow on the floor, and ice on the walls. The wind was blowing from a large gap in the wall a dozen feet away.

Elsa shuddered. This dilapidated corridor brought back dark memories.

"Where are we, Doctor?"

The Doctor licked a finger and held it up.

"Still Earth" he said eventually. "Some decades in the future. We did not jump very far." He looked hesitant for a second. "I wonder why she brought us here…" he mused.

Anna was looking around her curiously. Elsa glanced at her sister, clad in her light summer dress, and realised she was shivering.

"Anna! Get back into the… the TARDIS? It's very cold here."

"I'm OK!" she said through chattering teeth. "This is… amaz… zing, Elsa! We are i...in anoth...ther pl...place… and in th… the fut...ture!"

"Oh, seriously!" the Doctor said with exasperation. "Get back in, take the first door to the right then the second to the left, there was a dressing room there last time I checked, and grab a coat or something. Or better, stay in there and don't touch anything. Or quickly learn how to talk without your teeth clacking against each other like that, clac clac clac" he loudly clacked his teeth a few times "it's really annoying."

"Please, Anna, go" Elsa said, taking her sister's hand and gently pulling her back. "It's freezing in here. I don't want you to catch a cold."

"F-fine" Anna stuttered. "B-but d-don't g-go ex-explo-ploring with-without m-me!"

She doubled back to the TARDIS and quickly ran inside.

"Are not you cold?" the Doctor asked curiously. "It's almost minus 40 degrees."

"No… the cold never bothered me actually. I think it came with my powers. Are you not cold?"

"Time Lord physiology. I can be as cold or warm as I need."

"Time Lord? Is that a real title?"

The Doctor did not answer. He reached into his coat and retrieved a metal stick. As he waved it around, the stick emitted a whistling sound. Elsa squinted, looking at it.

"The man with the bow tie… you… had something like this, right?"

"Sonic screwdriver. Always carry a reliable tool with you, you never know when it can come in handy." He looked at the side of the stick and muttered something under his breath, frowning.

"What does it do, exactly?" Elsa asked, following him along the ruined corridor and away from the gap in the wall. The Doctor turned round a corner and stopped in front of a sturdy wooden door in a better kept wall of the corridor.

"Now we are getting somewhere" he said, looking at it. "It's locked. What do you make of it?"

Elsa looked at him cautiously.

"It means you don't like to answer direct questions?"

The Doctor smiled.

"Of course not. What would be the point if people always answered your questions? Life would be boring. Simpler, but very, very boring."

He pointed the sonic screwdriver at the door. There was a whistling sound and a click. Elsa gasped.

"So that's how the man… you… opened my door all those years ago." She refrained from telling him she had barricaded herself for months after that for fear of Anna being able to open it as easily and had eventually asked her parents to change the lock.

The Doctor cautiously opened the door. Elsa stepped back to cast a glance at the TARDIS in the other end of the corridor.

"Is my sister safe in there?"

"Young lady, the TARDIS is one of the safest places in the universe. As long as your sister refrains from doing something foolish, she is as safe as she could be."

Elsa bit her lip, hoping that the Doctor's definition of foolish did not mean being Anna's normal self. After a last glance at the box, she followed him inside.

They had entered what looked like an antechamber. There was a set of doors in the opposite side. Elsa looked a the torn tapestries on the wall. They looked strangely familiar. She slowly walked to one of them, but was interrupted by the sound of hinges creaking. The Doctor had opened the far doors wide, revealing a larger room where a fire was burning.

Elsa joined him in the room. The walls had been patched in places, and the windows had all been boarded shut. There were a few dishevelled chairs and a half broken table near the door.

"Doctor, what is this place?" Elsa asked, trying to make out the remnants of the crests on the walls. The light from the fire was not enough to see them clearly, but she was pretty sure they looked familiar. A horrible suspicion was growing in her mind. "Did we really… travel in time?"

"Yes" the Doctor answered curtly. He turned to her. "What do you make of this cold?"

"I'm sorry?"

"Cold is your area, right? Cryokinesis, insulation… Don't you have special cold senses?"

"What? No, I… I can control the ice and snow but… Listen, a year ago I could not even control what I did… Now I…"

"Is it the same cold than the one you can control?"

Elsa did not need concentrating. She had felt it the moment she had set foot out of the TARDIS. Only now did she dare put words on it.

"It's magical… It feels just like my snow, my ice. I can sense it. But I would never…"

There was a sound behind them. Two armed men had entered the room from a door lateral to the one they had used, carrying a torch. They wore tattered and heavy furs.

"Who goes there?" shouted one, raising his sword.

"Oh hello my good men, you must be the local guards. I always seem to meet guards first when I arrive somewhere. Could you please tell me…"

But the men were ignoring him. Their gazes had become fixed on Elsa, and they were whispering nervously to each other. Finally the first one pointed his sword at them.

"Who are you?" he demanded.

"I'm the Doctor. And this is, err… the one with the platinum hair…"

Elsa said nothing. She was pretty sure now of what the motifs on the walls were, and the way the guards looked at her made her fear the worst.

"How did you come here?"

The Doctor sighed exasperatedly and produced a small paper in a black wallet.

"Surprise inspection. Is that enough for you?"

The man walked cautiously forward and peered at the paper.

"Wood stacking inspector?" he asked dubiously.

"What?" the Doctor said, briefly nonplussed. "Well of course. I'm sure that with this cold you have lots of wood stacked everywhere. Would not want to stack it incorrectly."

"Who is she?" the guard asked, pointing at Elsa.

"Her? Oh she's called… something. Platinum. She's with me. Wood stacking inspector in training."

The man was looking at her nervously. Elsa noted that the second one was staying behind, his body tense.

"Fine. Now can we please see your wood stacks so that we can inspect them?" the Doctor ordered.

The guard hesitated, before eventually showing the door from which he had come.

"This way".

The Doctor strolled with assurance through the door. Elsa followed him hurriedly, trying to avoid the gazes of the guards. The two men followed them at a respectful but still uncomfortably close distance.

Anna slowly exited the dressing room, looking with awe at the door sliding shut by itself behind her. This room had been at least twice as large as the one with the console, and full of an assortment of improbable clothes of all shapes and sizes. She regretted not having had more time to explore it, and possibly play dress up a bit. But she had to meet the Doctor and her sister, who were probably having fun on their own.

She had managed to find a magenta cape with assorted mittens, along with a blue and black dress and black boots that looked a lot like those she had bought from Oaken a year ago, when she had been looking for Elsa. Even if this had been a dark day, this outfit now brought back happy memories, as she had been wearing it when she had met Kristoff and Olaf, and finally reconnected with her beloved sister. She had also discovered that her cape had pockets inside, something that lacked in her own outfits.

She quickly crossed the cavernous console room, briefly pausing to address a little salute of the hand to the central column protruding from the console. She could not really tell why she did this; it simply felt like the right thing to do. Maybe it was the sheer impossibility of the TARDIS, or maybe there was something in the patterns of blinking lights and the distant sounds she heard, but she could not help feeling that the TARDIS was far more than a mere machine.

She closed the door behind her, instantly feeling the cold bite her exposed cheeks. Maybe she should have chosen a warmer garment, she thought as she pulled the cap on her head. She hesitated a second, looking left and right, before walking briskly toward the part of the wall that was dilapidated. Squinting in the cold wind, she looked through the gap in the wall, but only saw mounds of snow and occasional hints of buried buildings.

She moved past the gap, and reached a crossing corridor, which was just as dilapidated as the first one. She walked a few steps, wondering where Elsa and the Doctor had gone and whether she should try the other direction. Reaching another gap, she looked through it and got a better view of the landscape before her.

She recognised it instantly. It was entirely covered in snow, and probably ice as well, more than she had ever seen it, but there was no mistaking the shape of the fjord or the mountains surrounding it. She knew them only too well.

She had spent years looking at them through her window, after all.

A/N: The temperature of minus 40 is the same in Celsius and Fahrenheit. I could not decide which scale the Doctor would be using so I chose the one temperature that is the same in both scales, since it was close to what I needed anyway.

I like Anna's winter outfit, so I decided the TARDIS would have a close copy of it in its wardrobe. It's not that big of a stretch.