Disclaimer: I recommend you read this at least once so you can't say I didn't warn you.
I do not know the Marvel comic books save for what Wikipedia might tell me. Therefore, the characters that appeared in the movies are going to be based more off their movie versions. I'm mixing real Norse mythology in as well, but with my own twist on it, so everything is going to be a little off what 'real' canon is, but not enough that I feel it's a real AU. Considering that Marvel AU's their own canon all the time, though...well...
There are also homosexual dealings. Keep in mind they're not actually related to each other if brotherly love taken to the physical level squiks you out. Also keep in mind that Norse Loki is Omisexual and will boink anything with a pulse, no matter what gender he or it happens to be.
The energy of the Tesseract faded from around the two Asgardians and Thor looked around in confusion, finding that they had appeared on the broken Bifröst Bridge instead of Asgard proper like he had expected. After a few moments, his head snapped to Loki and his eyes narrowed when he saw that the other had an amused crinkle to his eyes above the muzzle.
"How did you do this?" He demanded to know, but Loki only continued to look amused and Thor grit his teeth. Of course it was useless to expect an answer when Loki had the muzzle on and finally the God of Thunder sighed and reached out to grab the chain which dangled between Loki's hands.
"Come then, brother." He spoke wearily. "Your trial and our Father awaits us."
Panic settled on Loki's features and he set in his heels, leaning back as Thor began to pull him, though he very quickly realized that doing so did no good on the bridge where there was no where to hook his boots into. He tried yanking back, but that of course did nothing either. In desperation, Loki finally threw himself to the ground in hopes that doing so would finally make Thor stop dragging him, but Thor only sighed and continued to pull him along.
"Thy childish tantrum is not impressing me, brother." Thor spoke to the other.
Loki would have growled if the muzzle allowed any sound to escape him and followed the only option he felt was left to him. Taking advantage of the length of the chain binding his wrists, he threw himself to the side and managed to dangle himself partially off the Bifröst Bridge. He would have thrown himself further, even though it potentially meant that he would come across the Other and his master again should Thor lose his grip, but Thor yanked him back. It did succeed in finally getting Thor to stop hauling him along, at least.
"What are you doing, brother?" Thor asked, honestly perplexed and looking at Loki as if he wondered if the younger had truly taken leave of his wits. Loki only could roll his eyes in response, and gathering his feet under himself, he stood up and then motioned with a hand at the muzzle.
"Oh no, brother. You must think me truly foolish indeed. I am tired of your lies. I shall not release your silver tongue unless Father would deem it so."
Loki looked to the Tesseract container in Thor's other hand, then looked back to Thor and once more motioned to the muzzle, arching a brow at him.
"No, brother." Thor turned away, but then jerked when Loki kicked him in the back of the leg and then promptly followed up by dropping onto his back and kicking the hand holding the chain to force Thor to let go. He rolled backwards and came up in a crouch again, eyeing the older warily.
Thor turned back to him, frowning. "Why do you persist in this, brother? You have already lost, there is no point in continuing."
Loki looked off to the side and down off the bridge, but then he shuddered and looked back at Thor before getting to his feet and making insistent jabbing motions at the muzzle while giving Thor a scathing look that would no doubt cause a lesser being to combust.
Thor gave a heavy sigh. "You had best not make me regret this, Loki..." He put the Tesseract on the ground and stepped forward, bringing up both hands to press on the sides and front of the muzzle to cause it to retract and release.
"Ackh." Loki coughed and then spit to the side, working his tongue in his mouth. "Vile contraption! Who came up with that?"
"The Rock giantess, Skaði."
Loki looked shocked for a few moments, but then laughed bitterly. "My own teacher creating my entrapments." He smiled in cold amusement. "Do you think she holds my attack on Jötunheim against me, vile cousins to her kind though they are?" His eyes narrowed and he leaned forward. "Or was it her knowledge of what I am that inspired her to make such a painful contrivance?" He bared his teeth. "All of Asgard knows of my true heritage by now, don't they?"
Thor nodded, looking at the one he thought of as his brother in sadness. "Father knew the truth would come forth eventually, but he thinks you are only half Frost Giant. Therefore, you are still Asgardian, still one of us."
Hope seemed to flicker in Loki's eyes briefly, but it quickly died away again like an ember going out and he straightened up once more.
"You know I will be killed."
"What? No." Thor shook his head in adamant denial. "Our Father would never-"
"Your Father!" Loki snapped. "Your Father. Not mine." He looked away.
Thor looked at him in quiet pain for several moments before he gave a heavy sigh. "Enough. What did you do to the Tesseract to make it bring us here instead of into Asgard?"
"I did nothing."
Thor grabbed Loki by the front of his clothes, jerking him forward. "Do not lie to me!"
Loki flinched, then slowly brought his head around to look the older in the eyes. "I'm not." He stated. "I was amused when I saw it had happened. Perhaps it was drained by being used to open the portal and then bring us here."
Thor searched Loki's face for a few moments as if trying to discern if this really was the truth or not, then let him go and took a step back. "Your eyes..."
"...What of them?"
"They used to be green." Thor frowned. "Now they're blue."
"...Truly, Thor? Of all things, and you take issue with the color of my eyes?" Loki smiled ferally. "At least they're not red."
"...Come, brother." Thor once more sounded tired, emotionally wrung out. He brought up the muzzle. "We-"
"No! Wait! Wait!" Loki held up his hands and stepped back, only lowering his arms again when Thor slightly lowered the muzzle. "One last thing, Thor." He took a deep breath, then continued. "On your precious Earth, in the part of that world you so love to frequent called 'America'...they seem to have a...boon they give to those they have sentenced to death. A last request. I would ask of you to follow this, and grant me a last request."
"Father will not have you killed, Loki."
"You don't know that for certain!" Loki gave Thor a panicked, almost desperate look. "Sometimes he does things not expected. Thor...please."
Thor sighed heavily. "Make your request, and I shall consider it."
Loki shifted on his feet, looking uncertain and even nervous, gaze dropping downward. He stood like this for several moments before he lifted his eyes again, then swallowing hard, he stepped closer to Thor.
"We slept in the same bed as children, and all our lives have bathed, wrestled, played together...I watched you as we grew, watched as your shadow grew and I was cast within it." Loki brought his hands, slightly trembling, to rest on Thor's armored chest. "I watched." Loki whispered. "I always watched." He gave another hard swallow, and then leaned forward to touch his lips to Thor's. A brief contact, nervous and unsure and then Loki withdrew slightly, though he kept his hands there on Thor's chest.
"You keep claiming you love me. Well show me how much, Thor." His tone firmed, though his eyes searched the others face for some kind of sign. "This is my request. Show me how much you love me."
Thor furrowed his brow in puzzlement, and then slowly his eyes widened in realization. "Brother..."
"Not your brother." Loki corrected, though almost gently. "Please, Thor...please...if you removed these shackles, I could even become whomever you'd like..."
Thor smiled, though it was a sad expression and he brought up the hand not holding the muzzle to touch Loki's face. "You truly must think little of my wits to believe I would trust in your intentions that far after all of this deceit."
"Well..." Loki gave a wan smile. "It was worth a try."
Thor sighed. "Come. Enough time has been wasted." He brought up the muzzle quickly, but Loki pushed it aside by throwing his arms as much around Thor as the shackles allowed to grab his cape and give him a far less hesitant kiss than the last.
Thor stiffened, but to Loki's surprise and no doubt his own, he began to respond. When Loki finally pulled back, the both of them were panting, short of breath.
"Acquiesce or not, but don't keep me waiting." Loki rasped after a few moments, letting go of Thor's cape and lowering his arms to grasp the others hips instead.
Thor moved his own free hand slowly, bringing it to rest on the younger's hip in turn. "Loki..." He intoned softly. "Why now...?"
Loki smiled sadly. "Because I was your brother then," He responded softly. "and that was more important. Now...I have nothing left to lose..." He cast his eyes down.
Thor sighed softly and moved his hand to tilt Loki's chin up. "You will always be my brother." The two looked at one another in silence for several moments before Thor closed the small distance between their faces to initiate the next kiss.
Loki kissed him back, hands tightening on the others hips. It wasn't passionate, but it was a bit possessive and the younger found that he liked it. He didn't know or care why the one who called him brother was actually giving him what he wanted, but he wasn't going to complain about it in the least.
Thor pulled back slowly, eyes looking over Loki's face. "...When you say for me to show you how much I love you..."
Loki laughed softly and leaned forward to kiss the hollow of Thor's throat. "Everything." He whispered. "Or at least as much as you're willing to give me."
"...I don't..." Thor frowned. "I only know...with Sif...I..."
Loki snorted softly. "It's not so different, Thor. Pretend I'm her then, if your imagination can stretch that far."
"Mm..." Thor's fingers tangled into Loki's hair and then pulled his head back to kiss his throat. "I will try..." He trailed off when he felt vibrations traveling through the bridge and he turned his head to see horses approaching in the distance. He hastily let go of Loki and turned, dimly acknowledging Loki's hands taking the muzzle from him.
"Heimdall." Loki muttered resentfully and Thor heard the sound of the muzzle engaging as the younger put it back on himself. Loki then stepped to Thor's side and stood quietly while the riders approached and pulled up in front of them.
"Prince Thor." One of the guards spoke while another jumped off his horse to retrieve the Tesseract. "We have been sent by Heimdall to escort you back."
"Ah. Of course." Thor tried not to seem awkward and only stepped forward to take the reins of an unridden horse. He paused and looked around at the others. "Only one?" He pursed his lips, and then turned to Loki. "Brother. You ride."
Loki gave Thor a look and snorted through his nose, but he didn't give protest other than that and stepped forward to get into the saddle, accepting a boost from Thor to get seated. The guard who had dismounted to retrieve the Tesseract handed the object to another and offered Thor his horse instead. Shortly thereafter, they all save that guard, turned to ride back to Asgard and begin Loki's trial.
"Loki Odinson." Odin spoke, his voice booming throughout the throne hall. "For your actions against Midgard, I hearby sentence you to lie beneath the crust of the world you wronged and endure the venom of an acid viper dripped upon you until your term is deemed complete."
Loki, who had been staring down at the floor since being escorted into the hall, felt a myriad of emotions. Relief that he was not to die, but fear at the idea of being at the mercy of an acid viper for an untold amount of time and also, there was pain...heart pain that in spite of all that he had done, he was still Odinson, still a Prince of Asgard.
"Skaði." Odin addressed the eight and a half foot tall giantess standing by the throne. "Take Loki to his prison."
"Wait!"
Loki's head lifted and he half turned to look along with the others present as his wife, Sigyn, ran forward. She stumbled and fell just in front of Loki and though he was the prisoner and the one on trial, he reached down to help her up. She touched his arm briefly in mute thanks, and then turned to the All-Father.
"Great Odin. Though I do not ask of you to reconsider your sentence, I beg of you to please let me serve it alongside my husband. Allow me to catch the venom in a bowl so that his suffering is not constant, for I fear if his pain were to be never ending that his mind would shatter before he would have a chance to be redeemed!"
Odin smiled tiredly. "Your fidelity is heartening as always, Sigyn. If this is your wish, then I will grant it. Go and fetch the bowl, but do not tarry."
Sigyn gave a deep bow and turned to run off, lifting her skirt with her hands so she wouldn't trip again. Loki watched her go and then faced forward, dropping his eyes again. He could feel the glares of the court, and he found that he could not bear to meet their eyes, nor dare to look at Odin, or even Thor who stood by him. Most of all, he did not want to risk his eyes meeting those of Skaði, who had designed that which restrained him and would be the one carrying out his sentence.
Skaði. His once teacher in the arts of magic, or at least, the magics she could teach him. He had surpassed her long ago, or so he believed at least. Many of his powers were unique to Asgard, and had been oddly powerful for one of his age. It had taken Odin's confession that he was Laufey's son to explain it. But not all of it, no. There were still mysteries of which Loki knew not the answer to regarding himself, one of which was his ability to change form, a skill which no one else on Asgard showed the ability to do. An ability that he wished he could currently access so he could escape his fate.
After several minutes, Sigyn returned with a plain blue salad serving bowl and held it toward Odin for approval. Odin nodded in agreement of her choice, and then turned once more to Skaði, motioning her forward.
The giantess approached, drawing something out of her dress and holding it up, which appeared to be a gold necklace with a green jewel in the center. Once Skaði was certain everyone had seen it, she held it to Loki's throat and it latched itself there.
"Your powers to travel the paths between realms has now been taken from you." She informed the trickster. "So long as that collar is worn, you are bound. Only Thor Odinson and Odin All-Father can release you from it now."
What she wanted to say complete, she then drew forth the Tesseract to use its energies and transport herself, Sigyn and Loki to the location beneath the surface of Earth where Loki would serve out his term.
Magic ripped at Loki's clothing, tearing them apart and he found his arms yanked above his head by the chain before he was thrown backward with great force and pinned upon the ground by rock that had come to life to become his bonds. By the time he stopped seeing stars from his head hitting the ground, he found Sigyn kneeling at his side and he could hear the dripping of the venom from the snake as it fell into the bowl. Naked but still muzzled, Loki could only look at his wife gratefully for her sacrifice.
