Author's Note: If you have managed to get this far, congratulations, you deserve this well earned hint of smut. Some quick trigger warnings for masturbation and descriptions of physical (and to some degree emotional) pain.
The first night had been by far one of the hardest for Thor. After Vision had escorted Loki and Thor back to the penthouse the brothers had split ways and both receded to their respective bedrooms. Thor had craved a long and hot bath. He felt foul and dirty, he imagined that sleeping through two entire days and sweating throughout a fitful sleep would make him smell like the rotten carcass of a wild bilsnipe. Undressing himself was a tedious task, it made him feel raw with pain. The deep stab wound throbbed upon his chest and radiated pain down into his limbs with every slight moment. He tried to ignore the irony and prophetic nature of his current state. Thor was being forced to intimately deal with the repercussions of the mortal blow he had dealt his younger brother in his moment of rage. It seemed an almost fitting punishment. Still, that didn't make it any easier to deal with. While he had slept, someone must had taken the time to clean the wound, dress it it and wrap his entire upper chest with cotton compression bandages. It was only now as Thor stood stark naked in the reflection of the bathroom mirror that he unwrapped the dressing and examined the damage he'd done.
Loki's body was sickly pale and his completion was akin to wax as a result of the blood loss, while in comparison the wound was deep gash of an angry bloodshot red and the flesh surrounding it was raw. The sides of Loki's wound had been knit back together with black sutures which only served to make it appear uglier. He noticed that Loki's body had lost some tone and defining over the last two days and he appeared slim and undernourished, whereas before he had had the hint of toned muscle. Thor forced himself to inhale deeply in an effort to calm his raging mind. Distantly he could hear the deep roll of thunder. He tried to relax further, to ignore his guilt and the intense sensation self-loathing which was building within his gut. What he had done to Loki was so wrong that he didn't know where to begin to look for forgiveness. Loki may forgive him in time, if Thor was lucky. But Thor was almost certain he'd never forgive himself. As he stood shaking in front of the mirror he couldn't help but take in the image of his brother's nakedness. He had not seen Loki's body this intimately in centuries. Not since the days of their youth, when they had spent long summers afternoons in clear pools of crystal blue water. Dipping in and out of the water too cool off, nothing but their bare skin to shield them from the blistering sun. It had all seemed so innocent and childish back then. It was long ago now, yet a part of Thor remembered it as if it had only been yesterday. Loki had still been growing into himself at that stage. Adolescence was shaping him and slowly turning the boy into a man. Thor remembered observing his brother's body move, inspecting the way Loki was transforming. He'd desired to slow the process, to keep his little brother little forever. Though he had wonder after his brother's effortless grace, how each movement had seemed predetermined. The way his green eyes calculated every minute detail of their surroundings, the way his pristine white skin seemed almost luminous under the light of day.
It was clear now that that time had long since passed and Loki was now a man grown. His shoulders had broadened significantly, his limbs had grown past their once lanky disposition. His face had swapped boyishly charming features for a more dark and foreboding nature. And his green gaze had sharpened, allowing his eyes to project an air of illusive appeal. He admired Loki's slim hips and the was his torso hinted at the beginning of abs and the way his arse was perfectly firm. Thor couldn't help but feel himself stir as he beheld his brother's inexplicably striking physique. Loki had grown into an attractive man and Thor could not deny it. Forcefully he bit his lip and turned away from the mirror. He was disgusting and unworthy of Loki's brotherhood. How ratchet could he be that he would even fathom allowing himself to feel these repulsive passions, born from desire of his own brother's body. It was a blight on his character that he would even consider regarding Loki in such away. Most of all considering Loki had not been able to consent to Thor's witnessing of his naked form. Thor was meant to protect Loki, and of late it was becoming clear that he was failing in a spectacular manor. How could he desire the body he himself was trapped within? It was all simply insanity, Thor was meant to guard Loki from harm and yet he was the one inflicting all the destruction. First, he had temporally killed him and now he dishonoured him by entertaining such impure thoughts. He forced himself to disregard Loki's manhood as it stirred to become semi-erect, and instead he forced himself into the bath tub. He hissed as the blisteringly hot water met his skin. He forced himself to endure the pain as the water collided with the fresh wound and it sent tingling busts of white hot pain throughout his midsection. He decided that it was a fitting penalty for his latest depravities. Besides, a part of him enjoyed the agony. It provided a great distraction from the inner turmoil within his own corrupt mind.
In contrast, Loki's first evening spent trapped within Thor's body was rather pleasant. Sure, he detested having been forced into Thor's lumbering boar of a body. However, once the shock wore off he couldn't help but find it all slightly amusing, he had to admit that he wished he had thought of a trick this elaborate beforehand. The havoc he could have reaped with Thor's body under his control was endless in its possibilities. He was tempted to defy Stark. If he left the building looking like this he could bring the state of New York to its knees in a matter of minutes. He wondered briefly if it would infuriate Thor as much as he hoped it would. A smirk came to his lips as he imagined how his brother's face would contort in fury as he watched Loki bring Midgard down in a matter of minutes, all the while making it seem as if Thor himself had been the true villain of tale. However, when he realised it would be Thor's expressions displayed across his own face the idea suddenly lost most of its appeal and he decided against it. It would not be nearly as satisfying witnessing defeat and hopelessness spread across his own features. He would stay in Stark Tower, for now at least. It served him well to keep a close eye on Thor. Loki knew his brother was as dense as a log, and he wouldn't put it past him to do something stupid whist in control of Loki's body. What if the big oaf got himself killed while they were in this current predicament? Would that mean that Loki would be trapped like this for the rest of his incredibly long existence? He did want to even give that thought merit. Instead he retreated to his bed and decided to focus on examining Thor's body. He wouldn't deny he had always been envious of his brother. Envious of his natural physique and so much more. He was envious of the way Thor gained muscle effortlessly, the way his skin shimmered golden bronze even through the depth of winter, the way his smile was almost blinding in it beauty. But eventually Loki's envy had given way to attraction and desire. At first, he'd attempted to ignore it, push it down deep inside and never let it see the light of day. But that had failed spectacularly in a matter of months. His next resort had seen him attempt to withdraw from his brother's presence. In retrospect, maybe that had been his life's biggest mistake as the distance had only served to allow him to plant the seeds of bitter loathing which would later grow into his deep hatred of Thor and Odin. All he had wanted was for Thor to notice him, to look upon him, but the further Loki had withdrawn the less Thor remember to take note of him. And the less Odin had favoured him, To be fair, he was never present to allow his father to show him any favours.
He had dreamt of a day when Thor would return his feelings even though he knew it would never come. In the end, it had turned him cold of heart and his emotions became frayed which resulted in a resounding numbness. It had been a world of agony in which he existed, but he had known he had no one else to blame for its creation other than himself. There had been a small part of him that had been relieved the night he had discovered he wasn't actually related to Thor, but there had also been a sinking feeling. He knew Thor would never relinquish the title brother, that he would argue against all reason. In Thor's eyes Loki would always be his brother, blood or not.
But now, Thor's body was his. It belonged to him and he could do with it as he pleased. He didn't have to watch him from the shadows or merely fantasise about touching him. Loki felt Thor's cock harden beneath the fabric of his pants. Loki's heartbeat accelerated as he smoothed a large hand over the bulge. It was hot to the touch and Loki could help but moan slightly. He bit his lip as he pulled off the tee-shirt they had dressed him in while he slept and discarded it upon the floor. Thor's chest was covered in scars, both old and new. He eyes where instantly drawn down to one which rested just below his ribcage. It was small but thick with scar tissue. He hadn't thought it possible but somehow it served to heighten his arousal further. Knowing that he had permanently marked Thor's skin gave him an illicit thrill. He felt a smirk of pleasure graze his lips as he allowed Thor's manhood to spring free from his pants. It was flushed dark with arousal and Loki licked his lips in excitement. He almost didn't want to touch it, he was scared that the moment he made contact some sacred illusion would be broken. He inhaled deeply, closed his eyes, and made himself take Thor's throbbing cock into his wide hand. It stole the breath from his lungs and he was forced to hiss as his nerve endings burst into life with thrills of pure ecstasy. He made himself to wait a moment, to let him collect himself. Slowly the daze past and Loki began to move his hand in steady, tight strokes. His thumb caught and rubbed at the tip with each upwards stroke, he could feel the wetness there as his excitement grew. Cautiously, Loki reached his other hand down and cupped Thor's balls. Gentle at first, but slowly intensifying, his grip becoming tighter and tighter. It wasn't long until he could feel himself careening towards the edge of orgasm. The name uttered upon his lips as he came was the same as it had been for centuries now.