A.N. Fair warning, this is not a morally good Loki.
How to Earn an Enemy
When Sif awoke, she found the room was colder than she remembered. The shifting light from the fire still painted the walls in flickering orange and yellow, but the flames were lower now, the hearth covered in gray ash and smoldering embers that gave only faint imitations of their earlier warmth. She shifted, pulling her bare leg back beneath the sheets. The smoothness of the fabric was unfamiliar, fine and rich as the court dress she had worn earlier and that now lay puddled on the floor near the hearth where she had left it. Or he had, she supposed. He had undone the complicated closures and lacings, a simple spell, wordless and quick.
A chill crept across her back, and she realized he was no longer there. She turned towards the vacant spot, wondering when he had left, but in the dim light she saw him sitting in the chair by the window, his face illuminated half by the pale light of the stars on this moonless night, half by the dying light of the fire. His expression was unreadable in the shadows, casting his familiar features into strange shapes.
“Loki? Won’t you come back to bed?” she asked, her voice sounding too loud in the silence of the room.
“No, I don’t believe I will,” he said. He turned something over and over absently in his hands, a dagger perhaps, its form lost in darkness save when the light caught it and made the metal gleam. “I have no desire for sleep.”
“Is something wrong?”
“Not in the least,” he said, not moving from his place but still playing with whatever was in his hands.
He sounded as though he were smiling, but not in the gentle way she had seen earlier. At the feast, the dark jade of his eyes had softened when he looked at her, the delicate press of his lips against the palm of her hand quickening her breath. He had danced with her, fulfilling her fantasy of the prince noticing her at last as both warrior and woman. Drawing her to the terrace, every ridiculous comment about the charms of his silver tongue had proven true as he whispered in her ear, telling her of his love for her, how he had long desired her but thought her interested only in war, how her beauty on this night had driven him nearly mad with longing. She had been the one to stop his mouth with a kiss, but he had turned it into another battle, one that she was happy to lose. Between one heartbeat and the next they had disappeared from the din of the crowd and reappeared in his chambers. It had been fast, too fast to think, to consider. Heat and breath and skin were all that existed, and then exhaustion had claimed her, carrying her into the darkness of sleep at his side.
“Surely, something is amiss,” Sif said, feeling ill at ease.
“No. In fact, I should thank you,” he said, finally standing and coming nearer. “You see, you have done me a service this night.”
“A service?” she said. “An odd way to put it.”
“I agree,” he said. “Forgive me. It sounds like what one might say to a harlot under similar circumstances, and you are not that.”
Sif had drawn herself up against the headboard, her eyes still trying to make sense of the images around her.
“I do not think I understand you,” she said, her words becoming careful.
“No, not at all,” Loki replied. “You are not a harlot. A harlot would have at least asked for pay, but you have given yourself for nothing at all. I should not sully a harlot by comparing her to you.”
Her mouth fell open for a split moment before rage contorted her features.
“What means this?” she said angrily. “What manner of trickery are you practicing now?”
“My very dear lady, you have been the object of a bet,” he said. “The other party involved was my brother, who, as I am sure you know, is smitten with you.”
“This is utter madness,” Sif said, drawing back, holding the sheet tighter to her. “Thor has no love for me except as a comrade!”
“Oh, I assure, that is not true,” Loki said conversationally. “Well, perhaps not after the dawn brings all to light. I merely made him a wager that I could get you willingly in my bed this night, but he was certain you were too virtuous and too clever to fall for my paltry tricks.”
“Liar!”
“Yes, obviously, but then you already should have known that about me, my dear,” he said, and he sounded almost pitying. “I believe I shall enjoy both breaking my brother’s heart and having the use of his best sword for the next month. So, yes, I really must thank you.”
Naked or not, Sif flung herself at him from the bed, her nails positioned to claw at his flesh until blood came, but he was already dressed again, and by some power his strength was more than hers, grabbing her by the forearms and holding her at arm’s length.
“Now, now, sweet,” he said, the words dripping with condescension. “Be calm. As a lady, your reputation is, of course, ruined, but you may still be a warrior of renown even with this stain, and that has ever been the more important of the two for you.”
She tried to kick him in the shins to release her, but he wore knee high boots of heavy leather, and her feet were bare. Instead, she found herself unceremoniously pushed back onto the bed, where she landed with a strong desire to pluck out his eyes.
“You do realize you have made a tactical error,” she said, her gaze filled with hate.
“And what might that be?”
“As you said, you are a liar. No one will believe you,” she said.
“But I did think of that,” he said.
His hand reached to touch her face, and her instinct was to bite him, but then she noticed something strange. His fingers traced her cheek and back into her hair, but it felt wrong.
“What have you done?” she asked, horror beginning to spread over her heart.
She plunged her hands into her own hair, but instead of the long waves that swept nearly to her knees, on the left side of her head, it was cropped short, coarse and prickly.
“I shall treasure your gift to me,” he said, pulling a long tress from his pocket. “Well, for a bit, until I give it to Thor as proof that you lay with me. I fear that my skill in hairdressing is less than my gift with sorcery, though. It’s quite uneven. Would you like me to try again and cut off the rest for you? It’s already destined to fall beneath the shears.”
“One look at me and everyone will know!”
“Of course. That, my dear, was entirely the point.”
He disappeared, leaving her alone as dawn entered the room. Beside the chair where he had sat, she saw a pair of scissors glittering in the first rays of the sun. She breathed, steeling herself, refusing to allow weakness or tears to come forth at her plight. Instead, she picked up the scissors, went to the looking glass, and cut away what remained of her hair, snipping it close to match his handiwork. When she was done, she ran her fingers through what little remained, and she gazed at the unfamiliar face in the mirror, her hair shorter than any warrior’s. It looked like the fields after the wheat had been cropped. She left, fury in her heart, enough to fuel her endurance of what lay ahead.
When he returned, he found a pile of her locks on the floor, as good as a promise of revenge.