The story begins shortly after "Arthas: Rise of the Lich King"
Arthas' side:
"The snow glows white on the mountain tonight." Arthas smirked at his rhyme. He was standing over Angrathar or "The Wrath Gate" staring at the snowy plains of Dragonblight ahead of him.
The air was still, yet frigid. Back when he was alive this sort of weather would have been unbearable. But now none of the elements could really cause him any discomfort.
He looked again at the snowy plains and saw a figure. At first he thought that it must've been a well preserved female human he raised. But she was moving completely independently. He had no idea how this being made it to Northrend much less alone. But he wasn't going to allow foreign beings in his domain.
Arthas quickly opened a Death Gate and walked through it and arrived on the other side of the portal where he was standing in front of whoever this intruder was.
Upon closer examination he realised whoever this human was, she was alive, and she was not bothered by the frigid air in any way at all. Her hair was white like his yet it had a creamy look to it. Her skin was also pale but clearly alive.
The woman looked up at his relatively tall figure with an expression of minor shock but mostly curiosity and irritation.
Arthas really did not want to deal with a nuisance like this yet at the same time was curious about the peculiar human.
"What manner of being are you?" he boomed in his reverberating voice.
The woman jumped at the loud voice but looked at him with a puzzled look.
"I'm a sorceress!" she replied, it sounded like she had more to add but she decided against it.
So it was just mage of some sort. His mind flashed to Jaina but the image didn't bother him like it used to.
This young woman must've had a curious ability to come here, but still a mage none the less, tired of this interaction he thrust Frostmourne at her. But before Frostmourne could draw blood it was stopped, and Frostmourne made a hissing noise in disappointment.
The woman had shielded herself with a wall of ice. Ice that was powerful enough to stop the runeblade Frostmourne, which could shatter the diamond ice gathered from the Twisting Nether.
"What kind of mage has this kind of power?" Arthas thought to himself while pulling back to thrust Frostmourne again, but then found an icicle at his throat that looked sharp enough to pierce steel.
The woman spoke up, "Now you are going to tell me where I am and why do I keep seeing you in my dreams!"
Elsa's Side:
Elsa lay down in her bed made of snow wondering if she would have the same dream.
It had been about a week since she erected her palace of ice and every night she dreamt of a tall man with white hair. Not white like hers. His had more of a lifeless quality to it. He wore a helmet the resembles a crown in a way, his eyes glew light blue, and he wore armor that was shaped like skulls. She wondered what it meant as she dozed off.
When Elsa began to wake up she felt like something was different. She was still lying down on snow but she could feel the open air. When she opened her eyes she realised she was in the middle of a snow covered landscape. Everything was snow as far as she could see.
She touched her wrist to see if this was another dream. Nope. She could feel her wrist, she was awake.
She sat up and began to walk, she didn't know where she was going but it was better than just sitting there.
Elsa looked up at the sky to use the stars so she could have some idea of which direction she was going. But she quickly noticed that wherever she was, it wasn't Earth because there were two moons in the sky. One was white like Earth's moon. But the other was a strange light blue.
As she moved forward she saw an intimidating black-blue gate in the distance. It was clearly built to discourage people from approaching, but she decided to move towards it because she had no idea how far she'd have to trek to find some other sign of anything really and she was sick of walking through this snowy wasteland.
Suddenly an arch-like purple and black glowing portal appeared before her and a large figure walked out of it.
It was the armored figure from her dreams!
In a reverberating voice that was much louder than Elsa expected he asked "What manner of being are you?"
Elsa jumped at the booming voice, but quickly composed herself, then thought about the question. "What manner of being am I?" she thought to herself "What else could I be other than a Human and a…"
"I'm a sorceress!" she replied, she wanted to also say she was "Queen of Arendelle", but that wasn't true anymore was it?
The armored figure appeared to ponder her answer for a moment. Then suddenly thrust his large sword at her. By reflex she rose a thick wall of ice to shield her from the blow. The sword made a hissing sound it almost sounded, disappointed?
The armored man tugged his sword free but before he could prepare another thrust Elsa shot a pointed icicle at his neck and stopped it right before it impaled his throat.
"Now I can get some answers and he probably knows a lot."
Elsa rose her voice, the same voice she used to tell Anna she couldn't marry Hans and said "Now you are going to tell me where I am and why do I keep seeing you in my dreams!"