All characters © Marvel Comics

Summary: In which Odin screws up royally, the Casket of Ancient Winters is stolen, and something is the matter with Thor. Set post-Avengers, before Surtr uses the Casket in the Marvel-verse.

Note: This is a gift-fic for the amazing writer Helennotoftroy. Get well soon!

Thunder's Half

I.

"There is a catch," Odin said, looking at Gungnir thoughtfully.

Loki, already knowing this, veiled his inner rancor with something resembling a smile. "Naturally," he said. As if aiding the pathetic Midgardians in exchange for his freedom was not appalling enough. He knew what the Allfather was going to say; it did not help that Odin's good eye crinkled with a look that was genuinely apologetic. It made Loki's stomach curl over itself and bubble.

"The alteration bindings are over a thousand years old and are rightfully troublesome to break," Odin admitted, still eyeing his spear, "but I shall do so in hopes that you will return to me."

"Of course, so that I may be imprisoned in Urd's well once more, "Loki sneered, all attempts at a smile dissolving. "Tell me you are not planning to undo the spells of Mimir all in name of a single dwarf's frivolities? Really, father," his eyes narrowed, "you must be losing competence with your old age."

Odin finally tore his gaze away from Gungnir and peered at Loki from the dais. "If you had not destroyed our guardian armor Vidar would have never been capable of stealing the Casket in the first place." His brow was furrowed, skin folding over itself thunderously behind his shock of grizzled white hair.

Loki's sneer deepened at the Old Norse word for guardian armor. He much preferred the Midgardian moniker Destroyer.

"Is your beloved Thor so ill-equipped on Midgard that you call upon my, shall we say, latent physicality in lieu of the Avengers' efforts?" he asked. As if he had not been humiliated enough already.

Ignoring Loki's mordant, unblinking stare Odin replied, "Your true heritage is what makes you so apt for this task. As ironic as it sounds," he went on, gaze decidedly abstruse, "there is not a single warrior save for you to whom I would entrust the safety of Midgard. You are getting a second chance, my son."

After a minute of rubbing the scars around his lips and chin in a bitter burlesque of contemplation, Loki opened his palms, conceding. "Do not think you hold leverage over me, father. It is only because I detest the bowels of Yggdrasil so that I am accepting your offer," he said.

Odin's mouth tightened around the edges. "Loki," he began.

"You assume I enjoy being forced into a thousand-year slumber at the bottom of a well? I will do your bidding—not as your son," Loki said, overriding Odin, "but as your Jötun slave. I will fain retrieve the Casket of Ancient Winters in return for my exculpation and shall refrain from using it for, ah, further attempts at genocide." He picked at a spot of nonexistent lint on his robes and raised his eyebrows. "If you doubt my truths take a look for yourself from your little silver walls of Hliðskjálf."

"I do not understand it," Odin said, shaking his head sadly. "When did you become so bitter, my son?"

"Since a man found me and raised me as a bastard," Loki replied. "You should have left me to die, Allfather. I rather think I would have preferred it."

He knew his words had the desired impact and his stomach did another flip before balling into a tight knot because Odin actually looked guilty, the wretch. The lost boy in Loki almost protested. For all of the deception, Odin had still been a father figure. Loki quickly pushed that thought away, filling its void with an image of King Laufey baring his yellow teeth and breathing icicles into the snow.

"Loki. Perhaps your anger will fade and your heart will soften with time, but for now I banish you to Midgard," Odin said, quietly, final. He lifted Gungnir and abruptly, his voice rose. "White to black, blue to midnight. I now lift these curses from you—"he uttered a word of power in Allspeak—"and summon the enchantments of Freya to bring you to your destination."

Loki suddenly felt very cold. The sensation began in his chest and spread, like a spill of liquid milk, to his fingers and toes. He felt himself shifting; every molecule stretching and fading with the pull of magicks past.

"Do your duty and return to me, my son," Odin concluded, as Loki shimmered and vanished in a puff of light. He lowered his spear and he bowed his head in the silence that followed Loki's departure. He remained like that for some time.

"And forgive me."

x

With the Bifröst still in repairs, Asgardian ventures to other realms were temporarily limited. This certainly did not hinder the Warriors Three, who opted for stone-circle travel, as well as other Æsir vigilante who chose less desirable methods of transportation.

Loki vaguely recalled, some eons ago, having questioned Thor about the dark energy Odin had used to summon him in the absence of the Bifröst. Now, as he was dematerialized and scattered across the realms, Loki realized something terrible.

Odin's spells of travel (a product of Vanir's lost scrolls) undoubtedly consisted of dark energy. As a practicing sorcerer and agent of the ancient Seid of Freya, Loki descried this in a manner of seconds. He also recognized that the energy was all-corrupting. There were threads of Karnilla's black matter woven in, not to mention tendrils of Draugr, red snaps of revenge from Bergelmir, and traces of ash from Surtr himself. It would have terrified a lesser sorcerer down to the soles of his boots.

Dark energy in and of itself was only remotely problematic; if one did not know how to dispel its deleterious effects and let himself be corrupted by it, however, it could have unpleasant results. Loki gathered his own magic within the corners of his consciousness and dispelled the dark energy before it could start eating away at his essence. He was left clean, white, but with a sense of disquiet gnawing at his mind in the place of magic.

Was this what the Allfather had been using all this time to send Thor to Midgard?

Chances that Odin knew his spell was corrupt, or of its prolonged influence on those who were subject to it on occasion, were slim. If Loki were fully materialized he would have groaned as he realized what this meant. Thor. Of course.

Thor was not the imbecile Loki often made him out to be, but he was about as well-versed in spells as a battleswine. He would have had no idea that the magic used to transport him to Midgard was also slowly polluting him from the inside out. A double-headed snake, if there ever was one.

Had Tony Stark known of this, he would have sympathized.

x

Tony Stark, at present, was sneezing into the inside of his mask—an experience that shall not be recounted in order to preserve the well-being of everybody around. He subsequently let out a string of curses that made Steve glance over.

"You alright, Stark?"

"Peachy," Tony replied, sniffing. "I love my interface covered with mucus. Shouldn't there be a law, or something, against Scandinavia being this cold?"

"You should see the mountain peaks of Jötunheim," Thor said. "Goats there are known to freeze solid in the middle of the night."

"Thanks for the lovely image," Clint said as he rubbed his fingerless gloves together. "By the way, I like the getup." He gestured to Thor's armor, which was slightly different from what he had worn in New York. It was missing the six circular discs down the torso and the cape was a few shades darker, among other minor alterations, yet the garments still projected a sense of authority and power.

"My raiment is most suitable for the forests of Kiruna," Thor explained, gesturing around them. "We will need all reinforcements possible if we are to kill Vidar the dwarf."

"We're not killing him, just taking him down," Steve reminded him. Thor frowned, as if puzzled that there was a difference between the two expressions.

"If Vidar opens the Casket of Ancient Winters—"

"The Earth will be in mortal peril, we know," Tony said. "It's not like it hasn't happened before. Just take this guy back to your place once we stop him, like you did with Loki—"a mechanical arm came up and made a dismissive gesture in the air—"and do with him what you will there. Capital punishment isn't really up our alley."

"I would have his intestines strung out and made into a wreath," Thor remarked casually—almost as casually as he had described the goats of Jötunheim. Tony dropped his end of the end of the conversation then, deciding that whether serious or not, Thor's comment did not merit a response.

"All right, boys," Natasha said, catching up with them and sliding the last of her weapons into place on her belt, "are we ready to defrost?" Nobody noticed Steve's Adam's apple bob once in a swallow.

Clint paused a moment as the others passed him, his eyes still resting on Thor. His soldier's sense, which he had come to regard as an actual sense despite the cliché, was throwing off sparks. Something was off, but damned if Clint knew what it was.

It was not the looming battle but this lack of insight that bothered him most of all.

to be continued.