A/N: This was written in response to a prompt on an anonymous meme. Here is the full text of the prompt:

I wanna see Thor and Loki duking it out, no Mjolnir, no magic. Basically a fist fight. No weapons for either of them- and Loki totally kicks Thor's butt. He may not be a bodybuilder, but hot damn he can throw a punch!

I'd love for it to end with Thor on his back on the ground, Loki's foot on his chest holding him down, and Thor's like "OK fine, you win… again."

And somebody sees it, too. Be it the Warriors Three + Sif, or the Avengers, they witness the fight and mentally up Loki's BAMF stats. And please try to keep it gen, I just can't get past the they're brothers thing in order to ship it.

Mettle

Loki could see now that his victory was assured. Mjolnir lay in the dirt a distance away, and Thor's hands were bound by Loki's magics, unable to call for his hammer's aid. Loki smiled, triumph singing in his veins as he pinned Thor, a foot placed squarely on his chest. Thor groaned good-naturedly and let his head drop back. "Brother!" he said, tone resigned, yet friendly. "It seems I am defeated."

Loki grinned, releasing his spell's hold on Thor so that he could sit up. "So it would seem." He turned, then to Thor's friends. "So, mighty Warriors Three and Sif, what say you? Perhaps I am not such an unworthy combatant after all?" He spread his arms to them, inviting them to survey the scene for themselves.

For several long moments, the silence stretched on, the faces of Thor's friends unreadable as he stood behind Loki, gathering his wits and dusting himself off. Then, suddenly, Volstagg's laugh rang out, the deep sound of it reverberating in the air.

"Of course!" he said, but his sarcasm was not lost on Loki, who frowned. "Anyone can be a worthy combatant when they rely on trickery and magic to win. That is no true test of skill!" He grinned as the rest of them joined in the mirth as well.

"Indeed, dear friends," Fandral intoned, and Loki felt his annoyance roil further in his chest. "I am sure Thor would have proven victorious had we been more specific with our terms. Isn't that right, Thor?"

Loki turned to Thor then, and felt a brief flare of satisfaction at the discomfort that was so clear on his face. "Friends!" Thor said. "I hesitate to make such a claim. My brother is a skilled fighter even without his magics!" He smiled at Loki, then, clapping a hand on his shoulder. Loki smiled. Thor, at least, knew when he was bested, even if his buffoon friends could not recognize it.

"Perhaps another show is in order, then!" It was Sif who spoke this time, clearly unswayed by Thor's admonition. "This time, with no magic." She smiled, looking to Loki, a challenge in her eye.

Loki frowned again. Of course, he would not refuse, but this petty game irked him. How many times must he prove himself before these oafs would acknowledge the truth? He sighed. "Fine!" He said. "I will prove myself once again. But this time, let us make it a true test, for both combatants." He turned, so he faced both Thor and his friends. "Let us fight fist to fist, no weapons or magic to aid us. Let us see who truly has the mettle in combat, when there is inothing/i to sway favor in either direction."

Thor's eyes went wide, and Loki could see his reluctance written clearly in even that minute change of expression. His friends, though, seemed quite pleased with the idea, and so he could not refuse. The terms, then, were set. They would compete on the morrow, so there could be no blaming the exhaustion from today's fight for a loss. They would come with no armor, and no weapons, and Loki's magic would be bound for the duration. It would truly be a test of their fortitude, and Loki knew, without a shadow of doubt, that he would emerge victorious.

When morning came, and Loki worked the spell to bind his own magics, his resolve had not wavered. He wore nothing but a light tunic and a pair of soft leather breaches, and as he entered the sparring ring, he saw that Thor was dressed to match. The Warriors Three and Sif stood outside the ring, the morning sun only serving to highlight their delight at the upcoming contest. Loki knew that they anticipated the chance to see him fail, and he knew that they enjoyed nothing more than the chance to mock him. He knew, too, that he would not allow them such a chance on this day.

"Brother," he greeted Thor warmly, knowing that whatever the outcome would be today, Thor would accept it with grace and dignity. Thor would be proud of Loki's victory, even if it meant his own defeat. Thor was his brother, and, so it often seemed, the only one who appreciated Loki's unconventional valor. Thor desired success for Loki as much as for himself, and for that reason alone, Loki would fight honorably today.

Thor smiled at him. "Loki! Let us have a good match and settle this dispute once and for all, eh?"

Loki smiled. "Indeed."

Then there was silence, broken only by the sound of birds' song and the gentle rustle of a breeze through the leaves of nearby trees. The focus of combat settled itself over each brother, and in moments, the fight had begun.

For a long time, they stood at the ready, circling, but neither willing to break their stance to advance first. Loki waited, shuffling lightly on his feet, ready to dodge when Thor's patience finally broke. In this, as in many things, Loki was superior to Thor. His brother was rash, and wild, unable to wait patiently for an opening. Often, his relentless fury on the battlefield was an advantage, but here, it would be his downfall.

Loki waited. Thor did not disappoint.

He came first for Loki's face, his fist hurtling quickly, and with great force, but Loki was quick on his feet, ducking and feinting to the left. Thor recovered quickly, but in the short time that he was off balance, Loki was able to position himself for a quick jab to Thor's open side. He made contact with the delicate flesh just under Thor's ribs, could feel his knuckles press upwards into bone, and he smiled at the sound of Thor's grunt as his brother danced away.

It was too late, though. Loki had gotten the first hit, and Thor had become disoriented. Perhaps another would not have been able to see their advantage, to press it as Loki could, but Thor was his brother, and they knew each other all too well. Loki watched as Thor moved to guard his injured side. He darted forward just as Thor's guard hand dropped, and his right fist made solid contact with Thor's cheek.

He could feel the skin split under his knuckles, and more satisfying yet, he could feel the teeth cracking in Thor's jaw. The power of the hit resonated in his own arm, aching, but it only spurred him on. As Thor reeled, Loki swung his left fist up, catching Thor under the chin, and though skin did not split this time, Loki knew there was blood rushing forth from burst vessels underneath. It would be a vicious bruise. Thor staggered backwards, and Loki swung again, driving his fist into his brother's solar plexus, stealing his breath in the process. Then he swung his elbow around, driving it into Thor's face, and relishing in the feel of cheekbone cracking under the force of it.

He danced away, allowing Thor a moment to spit blood and a few teeth from his broken mouth. Thor looked up at him, raising fists to guard once again. Once more, they waited.

This time, Thor was patient, and he managed to find an opening as Loki moved around him. Pain exploded in Loki's face, and he was sure his own flesh had split open. His thoughts were confirmed when Thor's knuckles came away red with Loki's blood.

He did not allow Thor to press advantage, though, choosing instead to utilize a surprise flurry attack. He advanced on Thor with raging fervor, fists flying wherever he could make contact. Many of his blows glanced off of Thor's arms, but the point here was not to inflict damage, but to force Thor into retreat again. It worked, as Loki knew it would, and provided Loki the chance to drive his fist directly into Thor's nose.

The sound of cartilage collapsing under the force his blow was deafening. Blood rushed forth from Thor's nose in a torrent, staining his mouth, his blonde whiskers, and Loki's fist. Thor stumbled, forgetting his guard completely as his hand came up to cup his pulverized nose. So Loki swept a foot at his ankles, knocking his brother to the ground.

Again, he placed his foot to Thor's sternum, pressing gently, more a show for Thor's friends than anything. Thor looked up at him and groaned. "I think I miss the fights where you get to use magic, brother! My face certainly comes away from them with less damage."

Loki smiled. "Blame your friends, brother," he said quietly. Thor smiled at him, and Loki felt a small bloom of sympathy as he winced from the movement. He stepped back, offered his brother a hand up, and when they were both standing, he turned to their audience and said, "So it would seem I have proven myself again. What say you, Warriors Three and Sif?"

As it turned out, they had nothing to say. Their shock, and Thor's hand, warm on his back as they made their way to the healers were prize enough for Loki, though.