It had started so simply.
"You deny me, brother?"
"Your desires are madness, Loki!"
And like all simple things, it had become complex.
Jane, Thor thought, moaning pathetically.
"Shush, Thor, I'm not hurting you," Loki purred.
And it was true. For the moment, he did no more than kiss down Thor's belly, little provoking licks laid here and there, toying away from Thor's jutting length. The shackles that severed Thor's connection to Mjolnir and bound him to this simple, illusional mattress bit uncomfortably, but that wasn't the reason a tear dribbled down Thor's cheek.
To fuck his own brother—disgraceful. He disdained himself for allowing this.
And Loki was not pleasing him, not really. It was all in the way his brows arched, that nasty look he got when he was toying with an inferior. It had never been directed towards Thor before.
Thor wished continuously that it never would have been.
"How shall I torment you, brother?" Loki said, baring his teeth, the last word an insult more than a term of endearment, a curse if ever Thor'd heard it. "Oh! I have thought of a game."
Loki traced his hands over Thor, down, casually massaging his balls for a mere moment, and then over his perineum, scratching it lightly with his nails. Loki's face twisted into a snarl when he forced three unlubed fingers into his brother's unprepared hole, immediately starting a fast, punishing pace, relishing Thor's spasm of pain.
There was blood on Loki's fingers, but he didn't stop.
"You, the golden lion of Asgard, will be nothing but a Jotun's whore today."
"Loki—" Thor gasped, but he was silenced by a cruel twist of Loki's knuckles.
Loki poured the oil he summoned over his cock, masturbating himself erect.
"You are nothing, Thor," and Thor winced, hearing in Loki's words the echo of how Loki felt for himself. "And it is only fit that, as a Jotun's whore, I take you as a Jotun."
"Ah—ah!"
Thor yelled out, agonized, when the fingers inside him began to burn. He shouted obscenities, trying pitifully to shift his hips from Loki, to break the shackles, anything, but Loki simply shuffled forward on his knees and forced his oiled cock, now erect and blue, into his brother, a snarl on his lips, his eyes glowing red.
It hurt. It hurt like nothing in battle, for there was shame there, too, and the agony that it was Loki, his brother, who was tormenting him seemed unbearable.
Loki rutted into him, and Thor writhed and moaned.
The cruel, hysterical smile on Loki's face turned into a grimace at the pitiful way his brother shook.
Then he saw the tears.
Thor turned to the covers, trying to hide them, and Loki's eyes widened, an expression mirrored from childhood, when he'd taken a prank too far and Thor was in those deep pits of agony, too straightforward to outthink Loki and too proud to give into the rage or sadness.
Loki reached up, forgetting his Jotun skin, and Thor flinched from the caress, howling, a burn over his cheek in the shape of Loki's fingers.
Abruptly disgusted, Loki's sapphire coloring faded back to his usual pale tan. He pulled out and away.
His cock ached, though. Thor was still bleeding, was in fact bleeding more from Loki's cruel usage, and crying freely, as he hadn't since they were children.
Loki finished himself by hand, biting his lips, ashamed, and tenderly cared for Thor's wounds.
He kept him for another week, in which Thor recuperated and neither said a word to the other.
S.H.I.E.L.D. was happy to get Thor back.
It was only Tony Stark who noticed that the brightness had gone from Thor's smile—and it was in Tony Stark's arms that Thor learned that smile again.