"Come to visit me again, brother?" Thor's voice rumbled through the prison block like thunder in the distance.

Loki stepped out from the shadows of the stairwell. "Disasters are always so compelling to watch," he replied. Magics flared along the edges of the cell at his approach; Loki reflexively checked the field bindings, reassuring himself they still held.

Thor flicked a fragment of wood at the wall. "And here I thought you missed me." His cell was largely in disarray, Loki noted. No doubt the product of another temper tantrum. He rolled the bitter words he had come to say over his tongue and looked down at the prisoner on the other side of the field.

Thor lay sprawled across the floor, his back propped up against the wall. His armor had been taken away, and he was clad in nothing but his trousers and sleeveless undertunic. Even his boots had been confiscated, though why the guards had thought it a deterrent was a mystery; Thor could walk over broken glass in the berserkergang and feel it no more than were he walking over mossy ground.

He was magnificent even now, with his killing rage spent. His arms bulged with muscle, his broad hands, lethal whether armed or empty, were lax in his lap. There was so much power in Loki's adoptive brother, even caged like this: a lion with his nails trimmed. The defenses seemed laughable. "Have you another battle for me to win?" Thor asked.

"No," Loki said. It was sharp and too quick.

Thor smirked. "Can't stomach the bloodshed, little brother? You always were a coward. You would as soon run from a fight as face it."

"At least I'm not an oathbreaker," Loki said in measured tones.

Thor shrugged.

"Or a kinslayer."

Thor frowned up at him, opened his mouth to speak—

No, not yet. Let him dangle a while longer. Loki hurried on, talking over his question. "Your company, as ever, is uninspired, Thor," he said. " But I did want to ask why you do it."

Thor's cornflower gaze turned sharp and calculating. "Why, do you intend to take up the battle-fury? You would be good at it, Loki. Magic always did come easily to you."

Loki squelched the tremor of—something. Anger, hunger, he wasn't sure. He chose not to look at it too closely. He rolled his eyes. "I'll leave that to you. Hitting things until they break was more your way than mine. What I mean is, why a berserkr? You were already a formidable fighter, why strip away reason, too?"

Thor was on his feet in a ripple of muscle and scarred, golden skin. The black of his undertunic was stark in the bright white of the cell. He stared into the distance. "It is sweet," he finally said. "It is pure release. All that power, rushing through you, overtaking you; surrendering to it is the sweetest thing you can ever taste." His gaze refocused on Loki, and he stalked toward the barrier. His feet were soundless against the flags. "I can rip a head clean off its shoulders, with naught but these hands." He reached out to splay his hand against the barrier between them. Runes flared beneath the weight of his spread fingers; Loki imagined them about his face, crushing the life out of him the way he had seen them do to hapless einherjar. Thor barked a laugh. "I could rebuild Asgard's walls in a month, brother! What do you say to that?"

Loki kept his face impassive. "I would say it's unfortunate we have no need for walls to be built. Or perhaps, given your situation," he looked significantly to the prison block around them, "it's very fortunate."

Thor sneered at him, then turned away. In a vicious lunge he seized the remains of a table and launched them at the far wall, where they shattered and rained down in a shower of broken wood and splinters. "I can do that as a mere man," Thor said, his voice deep and rough. "I can do so much more in the trance." He turned to face Loki again, rubbing his hands together, and something in his expression made the hairs stand out on the back of Loki's neck. His voice, when he spoke, was soft. "Do you want to see if these walls can hold me back?"

"You know what will happen to you if you enter the berserkergang in here, Thor," Loki said, a sudden thrill of adrenaline surging through him. Oh, but how he wanted to see it again… It had almost been artistry, the way his brother had torn through the line of Malekith's elves, rending limb from limb and howling in maddened rage. Loki could see the arterial spray even now, in his mind's eye; could hear Mjölnir hum through the air like a dynamo. Could smell the sizzle of ozone through the reek of fear, blood and shit.

"Yes," Thor said, grinning. "But I have a feeling it wouldn't stop me." He clenched his fist and raised it to shoulder height, pressing his knuckles against the spell-reinforced stone of his cell. "'He must early go forth, who fain the blood or goods of another would get...'" His voice was dark, almost seductive, and the undertone of eager longing set Loki's heart skipping.

"You will find no wolf's blood or pelts here, Thor," he snapped.

Thor turned to him, face cracking into a dangerous smile. "Nervous, Loki? Afraid I might make good on my words?"

Loki stood firm. "'Within the gates ere a man shall go, / (Full warily let him watch,) / Full long let him look about him; / For little he knows where a foe may lurk, / And sit in the seats within.'"

Thor looked unimpressed. "If I wanted to leave, I would have already. I hardly need a pelt to do it anymore." He lowered his fist all the same.

Ice slipped into Loki's stomach, and he couldn't resist the urge to poke, to pry away the armor to expose the tender underbelly and then pry further. "Is that why you came back?" he asked, goading. He wanted to see it again. "Because you were bored? Because you wanted to try yourself against the walls of Asgard's prison? Come now, brother. Didn't you have any better places to be? Wait, no, of course not. You're nothing but a blunt instrument. No doubt you couldn't imagine anywhere else but coming back home, I swear your hammer is cleverer than you—"

"I came back to protect my family!" Thor bellowed, storming back to the window to glare Loki down. His fury was almost palpable, even through the warding spells. Loki found himself swaying back.

"And you've done a marvelous job," he snarled, finally letting his own anger slip through. Anything to mask his fear. "Father is in the Odinsleep because of you, and mother…"

Thor stared at him, breathing heavily. "What of mother?"

Loki swallowed. Now they came to the heart of it. "Mother is dead."

Thor's eyes narrowed, and he pounded his fist against the field. "You lie!"

"Not about this, Thor. Never about this."

He saw his words sink in, saw them make an impression on Thor's tiny mind. Thor backed away from the window, panting, his eyes wild and wide. He stumbled over the wreckage of a chair. He spun, turning to face the rest of the cell; Loki heard him inhale, heard the catch in his voice, saw the stirrings of power around him. His hands fisted at his sides, trembling; all of him was trembling, as though he burned with fever. The very air seemed to warp, bunching around him as though he were a pulled thread in the fabric in reality.

"Thor, no!" Loki pressed his own hands against the fields.

His words had no effect. Thor threw his head back and screamed, a long, unbroken howl that filled the tiny cell and reverberated through the walls. Loki flinched. Beneath his hands, could feel the magic shivering, bowing outward beneath the strain. Thor screamed, sounding more animal than man. Like an injured wolf, like a wounded bear. Like a man in pain. The sinews of his arms and hands clenched and knotted, standing out against his sweat-streaked skin; his shoulders bunched beneath his tunic as though readying for a strike. Loki sucked a breath, poised for whatever Thor might do.

With a guttural roar Thor rammed his fist against the wall, putting his weight against the strike. Loki saw the runes along the wall flare, saw the magical bindings shatter. He doubted Thor could see them, but it hardly mattered: there was a crack in the wall, now. Panting, Thor turned back to the center of the cell and extended his arm, his fingers extended in mute demand. Blood trickled down his knuckles

"No," Loki croaked. "No, Thor! Don't summon it!"

Thor paid him no mind, and in a fit of desperation Loki sent his double into the room. "Thor!" he shouted in his brother's face, staring down the almost-madness he saw there. "Stop! Mjölnir will not help you!"

"Out… of… my way, b-brother," Thor ground out with what must have been the last of his sanity, his teeth clenched around the words.

"Mother died in the final skirmish," Loki said as quickly as he could, adrenaline making his nerves sing. "She was with Freyja, bringing reinforcements from Folkvang. You used Mjölnir on them, brother. You summoned the storms and they burned." Loki remembered it all too clearly. Remembered Thor's wild, whooping cries, how he had laughed as thunderclouds coalesced above him. He remembered the purple afterimages of lightning ripping down from the sky as Thor raised his hammer to meet it. How he had swung that hammer at the oncoming elven army, sending bolts of untempered electricity through their ranks and mowing them down like summer wheat. How he had turned and in the same stroke cut through Asgard's oncoming relief. Loki remembered his own shock and horrified denial, and the sour taste of awe thick on his tongue. He remembered the sickening stench of charred hair and roasting meat. He summoned all of this, and thrust the sensations into Thor's mind, praying to the Ancestors his thick skull was just thin enough. They stood locked like that for countless moments, a millenia of heartbeats compressing between them as they fought each other's will.

Finally Thor's eyes widened, and his breathing hitched. The anger drained from his eyes. He lowered his arm.

"Loki," he said, and this time his voice broke from simple human grief. Loki sighed shakily before dispersing his illusion. His vision doubled over itself for a moment until he reintegrated, and he saw from his new angle the tears that stood out on Thor's face. He was staring down at his hands, and rubbing at the calluses Mjölnir had left on his palms. Loki turned to leave. "Loki, wait."

Loki paused, looking back over his shoulder at his adoptive brother. Waited.

"When is her funeral?"

Loki looked away, jaw working. "It was two days ago. You were unconscious from the berserkergang."

Loki didn't have to see Thor to imagine his broad, handsome, hated face crumpling, or to hear his soft exhalation of hurt. "Thank you, Loki."

Loki didn't answer. He turned and ran up the stairs, fleeing the scene. He left Thor to his grief and guilt.

END

0oOo0

A/N: Okay so I did all this research and obviously I couldn't squeeze it in the fic so here, enjoy my Viking Age nerdery.

The etymology of berserkr is unclear; early chroniclers translate it to mean "bare-of-sark," meaning they ran into battle shirtless or unarmored in their frenzy; more recent translators lean toward "bear sark," referencing their perceived animalistic/shapeshifting powers. We just dunno for sure. We do know they entered a trance-like state of battle rage (either through psyching themselves up by wearing animal pelts and drinking bear or wolf blood, or by ingesting special 'shrooms (not even joking)), often went without armor or care for their personal well-being, and they were nigh-uncontrollable. They would kill until they themselves were incapacitated, or until their bodies gave out. It's believed the berserkir were sworn to Oðinn, perhaps as a part of a mystery cult, and archaeological record has shown depictions of him dancing with wolfmen.

According to Grágás, the Middle Ages Icelandic law code, berserkir were outlawed due to their uncontrollableness and volatility. Before this, they often went together in war-bands or used as shock troops, and occasionally as royal bodyguards. Once Christianity came along, with its dim view of warrior culture and magic, the berserkr became a villainous figure, associated with outlawry and oath-breaking (when Thor and Loki call each other "outlaw" and "coward," they're calling each other one of the nastiest insults in the Norse lexicon: niðingr—honorless, cowardly, backstabbing and prone to sexual perversion).

Berserkergang is the act itself, the trance-state of going berserk. It was not just a feat of battle, however. Men could enter in the trance to perform great feats of strength. One might suggest the Wall-Builder and his horse Svaðilfari (yep, that one) were in the berserkergang, to get that damn wall built so quickly. "This condition is said to have begun with shivering, chattering of the teeth, and chill in the body, and then the face swelled and changed its color. With this was connected a great hot-headedness, which at last gave over into a great rage, under which they howled as wild animals, bit the edge of their shields, and cut down everything they met without discriminating between friend or foe. When this condition ceased, a great dulling of the mind and feeble- ness followed, which could last for one or several days" (Taken from an excerpt on the Viking Answer Lady's page on the subject).

Also, the random poetry bits were taken from the Hávamál, which is basically Óðinn giving advice and spells and talking about some of the stunts he pulled. For the curious: I used the Henry Adams Bellows translation, and Thor quoted part of stanza 58 and Loki quoted stanza 1.

Now you know.