It was the fourth anniversary of the Great Thaw, and the usual celebrations of one more year under Queen Elsa's reign were just hours away. But this year there was to be one additional celebration – an Arendelle royal wedding. Princess Anna, the queen's younger sister, would be marrying Sir Kristoff Bjorgman on this day, and the full complement of foreign nobles were on hand to wish the new royal couple all their blessings.

But the energetic princess who usually headlined any Arendelle royal celebration was less enthusiastic about this particular celebration than any other in recent memory.

"Do I have to?"

Even at the ripe old age of 22, Anna could still pout and whine like a five-year-old child…

"Anna, we've been over this a thousand times."

…but Elsa's patience could never be exhausted when it came to her adorable little sister.

"I know, I know," the redheaded princess grumbled in front of her body-length mirror, "we need heirs and Kristoff makes a good cover…" she lifted her arms up for Elsa to slip the dress on from behind her, "doesn't mean I have to like it, though." She crossed her arms and glared at Elsa in the mirror, showing her typical "stubborn Anna" posture.

"Aww, come on… give the poor guy a chance before you decide you don't like him." Elsa ran her fingers through Anna's hair as she spoke, adding bits of ice to build her hair into its proper ceremonial appearance. "Who knows, maybe you'll enjoy him so much you won't need me anymore?" She looked at Anna through the mirror and winked saucily.

There was a knock on the door. "Your highness," Gerda's voice called out, "the ceremony begins in half an hour!"

"We're almost ready, thank you Gerda," Elsa answered without turning to face the door. Then she turned Anna around in her arms and gave her a quick kiss. "Come on Anna, you can do this," she said encouragingly. "Just pretend you're saying your vows to me instead of Kristoff."

And the two royals went downstairs, hand in hand, looking like nothing more than an affectionate pair of sisters.

Later that night, after a great deal of rather exhausting celebrations, the newly married couple retired to their home just outside the castle.

Four years ago, upon his initial appointment as Royal Ice Master, Kristoff had been offered a room in the advisors' wing of the castle, along with the other members of the royal council. But Kristoff had declined, uncomfortable with being constantly waited on by servants. As a peasant by birth, and unaccustomed to the luxuries of palace life, he instead preferred to build his own simple house adjacent to the palace grounds, with an adjoining stables for Sven. This had become the official residence of the Royal Ice Master, and resembled any other artisan-class dwelling in Arendelle, distinguished only by the constant presence of one or two palace guards stationed at the entrance.

Over the course of those four years, due to the royal courtship, Princess Anna came to Kristoff's house quite frequently. They had agreed that she would move in with him, since she felt more comfortable in the cozy house than he did in the palace.

They entered the dark house, and Anna tried to keep herself awake in anticipation of the wedding night, only for Kristoff to say, "Anna, you look as tired as I am. Do you want to do the wedding night stuff tomorrow and get some sleep? There's no rush…"

Anna easily agreed to that suggestion with surprisingly little disappointment.

The next morning Anna woke up to the smell of ham and eggs from the kitchen, Kristoff making breakfast since he normally arose earlier than she did. She lazily stretched out for a while and before she moved to get up, Kristoff came into their bedroom with the food.

"So… do you want to eat first or… you know?" Kristoff gestured between them, his hand moving back and forth, the awkwardness making his meaning clear. Anna hesitated, looking back and forth at her husband and then at the tempting tray of breakfast in his hand…

"Um… can we eat? Not that I don't want to – uh – but the food's going to get cold and we'll still be here anyways - ?"

Smiling affectionately, Kristoff set the tray down between them, and they ate on the bed. When they were finished, he moved the tray with its empty plates onto the floor next to the bed.

"So… what now?" Of course, Anna was no virgin, but the nervous tremor in her voice sure made her sound like one in that moment, which didn't surprise Kristoff in the least (as he still thought she was one).

"How about we start with a kiss?" Kristoff suggested.

They did so, and it proved to be not unpleasant for either of them. Kristoff wasn't quite the same as Elsa, but Anna could close her eyes, ignore the bulkier size of Kristoff's arms around her and the rougher texture of his face and hands, and almost imagine Elsa being there instead.

They pulled apart and both opened their eyes again, staring into each other's eyes.

"So… we should probably take these off, then?"

Kristoff nodded in agreement. They shed their few nightclothes, tossing them to the foot of the bed. Kristoff gently laid Anna down on the bed and crawled over her, then closed his eyes and felt his way along her body, applying gentle kisses from her jawline all the way down her body to her sensitive parts. She lay back and closed her eyes, pretending. At first his rough and chapped lips spoiled the illusion for her, but once he began using his tongue, things got a lot better. Even if he wasn't her true love, he was an attentive and considerate lover, and actually did bring her to an orgasm with his mouth before finally flipping her over on the bed and thrusting into her from behind.

The months went by, and they settled into a routine. Kristoff was frequently away due to the ice business, but always endeavored to spend at least every other week at home. He loved his work, and was always excited for his next ice-harvesting trip by the end of his weeklong stay at home. Anna was quite happy with this arrangement, and truthfully preferred those weeks when Kristoff was up on the mountains, since she could sleep over with Elsa for those nights. In any case, while he was home, Kristoff never failed to fulfill his marital duties whenever Anna was up to it, and he always made sure she came before he did. But it just wasn't the same; no one could ever replace Elsa.

Elsa always seemed to be rougher and more possessive with Anna on the day after Kristoff did his duty as a husband. Anna noticed this pattern within a few months, but never mentioned it to Elsa. Instead, she used it as extra motivation to keep trying for heirs with Kristoff. The thrill of keeping a secret from both of her lovers almost compensated for the fact that she was knowingly married to the wrong one for the sake of her royal responsibilities. It never occurred to Anna that her dutiful husband might have a secret of his own…

Things went well until their one-year anniversary.

Anna normally spent her days with Elsa, being "the Queen's right hand," only returning to Kristoff's house for dinner (which she usually brought with her from the palace kitchens, a treat for Kristoff after his delivery rounds across town). But on this day, at Elsa's insistence, Anna went home to her husband early – bearing Elsa's anniversary present for the couple: an intricately carved set of animated ice figurines depicting Anna and Kristoff ice-skating together, holding hands. Kristoff loved ice, especially Elsa's ice sculptures and carvings, and Elsa often regretted that he could never be allowed to know just how much she had to thank him for.

Thus, Anna strolled into the cozy little house an hour earlier than originally planned, with Elsa's gift in their cloth bag, ready to surprise Kristoff. His sled was parked right outside the door, chained to its post, so Anna knew he must have gotten home before she did. He had promised to try to be early for their anniversary.

After checking all the rooms in their house, Anna decided that Kristoff must be in the backyard or in the stables with Sven, as he often was. So she proceeded out the back door, gave a quick glance at the yard (no Kristoff) and then turned and knocked on the stables door. "Kristoff? I'm home!" No answer.

The door was very thick wood, though, and more than once she'd found Kristoff napping in the straw with Sven, not having heard her knock. So Anna pushed open the door…

…and froze at the sight of Kristoff, naked and sweaty, gyrating behind Sven as he thrust into the reindeer's hindquarters and grunted in pleasure. The same sound she had often heard when he took her from behind and filled her with his seed…

Evidently neither Sven nor Kristoff had heard her knock, as they both froze in mid-thrust upon looking up and seeing Anna, both of their expressions morphing from pleasure to horror at being discovered.

Anna stood in shock as she slowly put two and two together – Kristoff was always excited to go on his weeklong ice-harvesting trips, alone with Sven – suddenly it made terrible sense why Kristoff always favored the doggy-style position in bed – and then she fought back a suddenly rising tide of disgust welling up in her abdomen and crossed her legs unconsciously and dropped the satchel in her hand as she realized that the part of her husband that had been inside her had also been inside the reindeer's…

At least Kristoff had always been considerate and taken a bath before getting in bed with her, but still –

Anna squeezed her eyes shut with all her might, and then counted to ten, praying that it was just a bad dream or something…

When she opened her eyes again, Sven had begun to smile, even though Kristoff was still frozen in horror – the reindeer dipped his head, bowing low as he looked up at Anna with a seductive expression, beckoning her forward with one front hoof –

And that's when Anna screamed and ran faster than she ever had in her life.

In a blind panic she ran, the horrible vision burned into her eyelids every time she blinked, not even thinking as she ran out of the house, and down the street, and back into the palace (the guards stepping aside for her with slightly puzzled looks) and through the great hall and up the stairs and down the hallway as servants scrambled out of the panicked princess's way. She skidded to a stop in front of Elsa's study and barged in, her sister jumping up from her chair in surprise and hurrying around the desk with a concerned expression.

Anna dashed into Elsa's arms and almost bowled her over, knocking her back against the desk and crushing her into a giant hug as she pleaded into Elsa's ear. "Elsa. Please make me forget what I just saw…"

Naturally, Elsa's first reaction was worry. "Anna! What's the matter? What did you see—mmph!" She was interrupted by Anna pulling her into a searing kiss, staring into her eyes with a pleading expression. Elsa felt her body responding to her true love's presence, but…

"Anna? Please, what happened?"

Anna completely ignored the question, desperately tearing at Elsa's dress and grinding against her as she begged in gasps. "Please… distract me…"

That was when Elsa understood what exactly Anna needed from her. She gulped once and nodded. "Come on, let's move to the bedroom," she said, pushing Anna back just enough to grab her arm and lead her the short distance down their hall to their room.

The moment the door was shut Anna pushed Elsa against the door and ripped her dress open with one pull while crashing their lips together again. Elsa quickly set to work pleasing Anna in all the ways she knew how as they quickly shed their clothing on the way to the bed.

Meanwhile…

A hastily-dressed Kristoff burst through the palace gates into the courtyard, the guards stepping aside for their frazzled prince just as they had for the frantic princess a short while earlier. He barely saw them, his mind filled with the need to apologize to Anna and beg forgiveness. He'd always known he wasn't Anna's true love, and she wasn't his either, but she was still his friend and wife, and he had failed to protect her from the upsetting knowledge of his real true love. He was at fault, so now it was his job to rush after her and calm her down as soon as possible… hopefully before she could run to Elsa and bring her icy wrath down upon him.

Kristoff knew there was only one other person than himself that Anna would ever run to after such an upsetting discovery, especially when he was the cause of it. If he wasn't fast enough to apologize to Anna before she told Elsa, his only chance of survival would be to gain Anna's forgiveness and hope she could talk Elsa down from her inevitable (and justified) rage. Kristoff's lungs were burning and his heart was hurting from the exertion, but he pushed on. The two sisters were his only friends aside from Sven. He couldn't lose them both.

Dashing into the main hall, Kristoff called out to the first servant he saw as he ran up the stairs. "Have you seen Anna?" "Yes Your Highness, she went that way!" "Thanks!" And Kristoff bolted up the stairs as the royal household continued to wonder what was happening, though they all went about their duties with impeccable responsibility. Whatever had happened was between the Prince and the Princess, and none of their business unless they were told otherwise.

"Have you seen Anna?" "Yes, she went with the Queen to her room." "Thank you!"

Moments later, Kristoff threw open Elsa's door. "Anna, I'm sorry!" he started to say loudly, ready to prostrate himself before the two royals…

But his apology trailed off as he was met with the sight of Anna naked and writhing on the bed while Elsa's fingers pumped in and out of her and she let out a moan of pleasure more intense than any he'd ever been able to draw from her… which trailed off awkwardly as she looked over, in the throes of her orgasm, and saw him in the open doorway.

Time seemed to stand still as the three royals gawked at each other.

Author's notes:

Hey, it's canon, the movie says so!

Or at least, this is the obvious result of taking everything literally.
(Edit: No condemnation implied; I'm just saying what is, not whether it's right or wrong…)

Canonical support for Elsa/Anna since it's not directly stated in the movie: elsannaheadcanons tumblr com/post/78785783046/an-au-of-a-sorts-only-not