Okay, disclaimer first: Thor belongs to Marvel. I own none of this.

Bear in mind, I'm writing this story from a strictly movie-verse angle. I didn't try to get things to line up with the comics or the myths. These are just my speculations that I think help explain what was going on in the movie.

And I know the Avengers just came out. Better late than never.

Prologue

Jotunheim

So much for getting answers.

Jotun after Jotun hurled itself at the Asgardians, heedless of the danger. Every stroke of Asgardian steel felled a Frost Giant; yet for every one that fell, another stepped up to try its luck.

In the middle of it all stood Thor, hammer whirling, laughing as if the life-or-death battle were no more than a game. At least he was enjoying himself; around him, his friends and brother were fighting for their lives. The Frost Giants pressed them by sheer weight of numbers, and their ice magic was beginning to take its toll.

Volstagg found himself in the middle of a wrestling match with a particularly large Jotun. With one hand it caught his axe, sending ice crystals down the handle. The other seized his forearm, its icy grip searing his skin. Volstagg howled and wrested himself away, felling the giant with a blow before looking down at the frostbitten handprint.

"Don't let them touch you!" he shouted.

Not far away, Loki heard him and caught his meaning on the fly. He was doing well; his knives and magic had claimed more than one Jotun life. Smallest and weakest of the Asgardians, he was by no means defenseless. He was clever, that was his strength. And if anything got them out alive today, it would be Loki's brains instead of Thor's brawn, he thought.

Blast it, where is that guard?

A Frost Giant dropped from a ledge overhead. Loki closed the gap before it could fully rise, catching it with a swift thrust of his dagger. The giant fell to its knees, seizing Loki's arm as it went down. He jerked back, expecting pain, but none came, even as the temperature in his arm dropped scores of degrees at once. Instead, the fine scales of mail that covered his arm broke loose and fell rattling to the ground. Loki felt a chill spreading up his arm, but what froze his blood was this: looking down, he saw the color of his skin changing, spreading out from where the giant held him. Not the charred black of frostbite, but blue, spreading to the tips of his fingers and up beneath his sleeve, turning his arm the same color as the hand that gripped it. Loki's eyes widened in shock. Panicked, he glanced up and saw comprehension creep into his assailant's eyes. He put an end to it with a quick thrust of his dagger and wrenched away from the dead Jotun. Holding his hand up before him, he watched it rapidly return to its normal color. There was no wound, nothing to indicate the change that had just taken place; but the ruined mail sleeve proved to him that he had not imagined it. He glanced around franticly. The others were busy with their own battles. No one had seen what had transpired.

What just happened to me?