The wind kept Elsa company within her frosty palace. It sang to her, and she ahd made a habit of listening to it on the balcony each night. Her newfound freedom was still exhilarating, but there was little for her to do, save to test the limits of her power.
So, during the day Elsa crafted furnishings for her new home and raised minions from the snow and ice. Though fun and loyal, they were unable to speak, and so did nothing to keep her company. By the time night fell, the loneliness was unbearable - and so Elsa went out onto her balcony and listened to the whispers the wind brought her.
But tonight...tonight was different.
At first she heard nothing, but then a powerful gust began to pick up. Upon it, Elsa heard a familiar strain of music - one that she herself had given life to.
Fascinated, the snow queen used her magic to give the wind strength. She listened to the unfamiliar words it brought to her and sensed in them a kindred spirit - someone just as lonely and misunderstood as she; someone with a frozen heart.
The song reached its climactic ending, capturing Elsa's heart as the harsh voice cried out:
Let the dead rise u-u-up! -
Undeath never bothered me anyway.
Elsa listened to the silence that followed, for some reason breathless. Then, to her surprise, the song began again. It seemed the mysterious stranger needed to get the words out. The snow queen listened in silence for a moment - then, her heart pounding, she sang back to the unknown voice with the original words of the song. Their words wove together at the same time as their hearts, a strange duet of ice and death. A common link of loneliness, of powers misunderstood and feared, bonded the duo.
Elsa's heart continued to pound long after the song had ended. Here, she knew, was someone who would understand her. Here was one with whom she could be herself.
A strange sensation filled the Lich King's empty chest as he stood atop his lonely mountain. The lilting voice that had joined his echoed around him, given life by the storm.
Arthas stood there in silence, listening to the faint remnants of their duet, until Invincible nudged his shoulder curiously. Arthas reached back and soothed his friend by stroking his nose. Then he withdrew Frostmourne from the ground with a shower of snow. Sheathing it, Arthas turned and mounted Invincible.
"I'm going to find that woman," the Lich King swore.
...
Beneath the citadel, the ice upon the frozen heart had begun to crack. A golden-haired little boy watched it - and smiled.