Author's Note: This starts a few minutes before the movie ends, making some tweaks to the ending events of the movie to set up for the rest of the story. Also, you have /frz/ to thank (or threaten) for this even existing. I don't know how I'm managing to write this.
Elsa, Anna, and Kristoff waited nearby and watched as a pair of guards pulled Hans from the water. Anna was still upset, her punch doing little to calm her attitude towards the now-soaking wet prince. She asked her sister, "So... what are you going to do with him? He tried to kill both of us!"
The Queen looked at her sister with a soft expression for a moment before straightening and issuing a command to the guards holding Hans, "Bring him to the center of town. We'll make an example of him." She turned to another nearby guard and said, "Find the Duke of Weselton and his men, as well. He had some part in this and will need to answer for what he's done."
A short while later a crowd had formed at the center of town. Many of the townsfolk had heard whispers and rumors of what had happened with the prince and what was going to happen to him now that their Queen was back. A squad of guards surrounded the four captives and held the crowd back, leaving a moderate sized area clear for whatever was to happen when the Queen arrived.
After a short absence spent at the castle changing outfits, Queen Elsa slowly made her way to the gathering, followed by Anna, Kristoff, and a handful of royal guards. Her sister stole nervous glances at the Queen as they progressed through the crowd, unsure of what was going to happen. She wanted Hans brought to justice, but she didn't know what Elsa had planned for him and the Duke.
As the Queen and her entourage stepped past the perimeter of guards, Elsa slowly turned and addressed the crowd, "People of Arendelle, as well as my guests and visitors, I apologize to you for what has happened. I lost control of my emotions and did a terrible thing to you all. I know I've made a mistake, but it's not one I anticipate will be repeated. My hidden ice powers can only be accidentally revealed and cause an eternal winter once before they stop being hidden." There was a small murmur growing in the crowd. "I will find a way to atone for what I've done and make it right with you." Elsa glanced at her sister as she spoke the last few words.
Elsa turned to the four men in the very center of the square and uttered a quiet command to the guards holding them. They quickly obeyed and separated the men, bringing one to each corner of the cleared space.
Turning back to the crowd, she continued, "I am not the only person who has made a grievous mistake recently. These men," she paused and gestured to the three from Weselton, "they tried to murder me after I fled Arendelle. I cannot forgive these actions." The Queen motioned with her hands and formed cages surrounding the men. Made completely from brilliant translucent ice, the bars were thick and sturdy and left the men with little room to move.
Elsa moved to Hans and began again, "And this man... Prince Hans of the Southern Isles..." she cooed as she walked around him, "not only did he try to kill me, he tried to kill my sister, Anna, and usurp my throne." The Queen stepped away from him and brought her arms together, encasing him in a cage similar to other three. But this one was more... menacing. It had jagged protrusions on the bars and the floor that jabbed into Hans as they grew and made him squirm away, desperate to not be skewered by the icy spars. To his relief, they stopped before they punctured his flesh but not before they forced him into an unbearably uncomfortable position. Elsa turned away and raised her voice as she continued, "Let him be an example to all who would seek to harm or threaten my kingdom, my person, or my family. Send word of his betrayal and his punishment as far as your ships can carry you, so that others may learn from his mistakes." Satisfied that she had made her intentions clear, Elsa walked next to her sister, took her hand, and began the walk back to the castle.
Anna stumbled as she hadn't taken her eyes off of Hans and his newly formed prison. Catching herself, she matched her sister's pace and looked up at her, and with a hint of worry in her voice she asked "You're just going to leave him there in the middle of town?"
Elsa replied without looking at her sister, "For now. Would you prefer I give him a room in the castle? I think he deserves a few sleepless nights in his cage. I'll decide on a more permanent solution later." She squeezed Anna's hand and smiled at her, "I wouldn't waste time worrying about him, Anna, when we have so much lost time we have to make up for together." Anna returned her sister's smile and felt her cheeks grow warmer as she thought about finally being able to spend time with her beloved sister.
Late that night a hooded figure stole away from the castle and made its way swiftly into the city center. Peering around the square and seeing three men sleeping uncomfortably curled up in their cages and a fourth squirming and grimacing as he did what he could to keep from impaling himself, the figure walked to the fourth man and chuckled.
At the sound, the man turned his head to see who was approaching him. He couldn't make out the face underneath the hood, but he was surprised and started to relax as he noticed the pointed ice of his prison recede into the bars. "Starting to warm up to me, your majesty?" he asked with a smile and a weak voice.
The only response he received was a grunt of derision and the feel of cool ice wrapping around his hands, feet, and waist, locking him in place as the bars in front of him disappeared. Something flashed in the figure's hand as light from a nearby lamp fell onto it and the prince's eyes widened in fear as he recognized the object. One final patch of ice surrounded his throat, locking his head in place as the figure closed the last few feet between them and brought the jagged ice knife to his face.
"This is for what you did to my sister," said Queen Elsa, of Arendelle.
Hans screamed.