A/N: My second attempt at fic-writing. As with my first fic, don't expect much out of this one. I think I tried a little too hard to make it angsty and ended up failing miserably. Anyway, hope you enjoy regardless of my bad writing!
In the very beginning, it is Loki who has the nightmares.
As a foolish child, Thor often didn't understand when his younger brother woke up in the middle of the night, crying. He didn't know what to do, or why a mere flight of the imagination during their sleep would drive Loki to tears, so most of the time, he'd pretend to still be asleep and let Loki softly cry himself back to sleep.
Sometimes, Thor would hear their mother would come into the room that the two brothers shared and comfort Loki, whispering affectionate words to him and stroking his raven-black hair to soothe him. She'd assure him that he was safe and that everything would be fine if he'd go back to sleep. Thor came to realise that these visits from their mother were effective, but only as a temporary fix, and the nightmares did not cease to plague and poison his dear little brother's mind.
Thor wondered if these constant nightmares of Loki's were the reason why he never wanted to play outside with him and his friends, and would instead choose to stay confined strictly to his bedchambers with the company of his books. He wondered if it was why his brother would remain taciturn and reserved in the presence of others, and he wondered if it was why, as the years passed, his emerald eyes became colder and colder.
At the age of eleven, although he was still a child, Odin said that Loki was much too old to be having nightmares. The Allfather said that it was immature and disgraceful, and ordered his wife to stop going to comfort Loki at night, for the younger prince should learn how to face and fight the demons that visited him at night by himself. Thor was a strong boy and never cried, he'd said, so neither should Loki.
Loki was affected by Odin's words and took their father's harsh treatment of him as an insult. Nevertheless, he acted very much like he always had as they prepared to retire for the night, bidding Thor a good night as they climbed into their beds.
The first few nights, Loki would wake up, as usual, in tears, wrenched from slumber by terror, and also as usual, Thor would ignore these occurrences and pretend to still be asleep. But no matter what, Loki was his little brother, and very precious to him. Thor longed to fight off whatever evil attacked Loki at night, very much like how he had chased away the other impudent children who had teased Loki when they were younger. Finally, he couldn't bear to hear Loki cry anymore.
One night, Loki woke up with a terrified cry. Thor listened to his quick, scared breathing and muffled sobs. He knew his brother was trying to keep quiet. Slowly, Thor slipped out of bed and padded across the room, kneeling at Loki's bedside.
"Brother," he whispered, "It's alright, it was only a dream. Don't cry."
"It's you," Loki said, voice nearly hysterical, "It's you, it's always you!"
"What are you talking about?"
Loki gripped Thor's arm so tightly that he thought his circulation might get cut off. "I always see you and me, and white, everything is white, and it's so cold, Thor. It's so cold and it feels so real, and I am freezing and dying, and then there is a monster, a Frost Giant – enormous, with blood-red eyes and a face like cracked ice. I can only watch as he kills you, brother. I can't move, and he's tearing you into pieces and suddenly everything is no longer white, but red, and you are gone, and he's coming for me next. I can feel his hands around my throat, and I can't breathe, and I'm so cold, and…and…I scream and scream, but no one hears me, and…and…Brother, I…I couldn't help you…"
Thor embraced his precious little brother tightly, and let him sob into his shoulder.
"It was a dream, and nothing more," he assured Loki, "It doesn't mean anything. Don't worry, Loki, you're safe with me. When I'm King, no monster will dare to come near either of us. Even the stupidest beast would know to think twice before touching the King's brother. I'll protect you and slay any monster that so much as looks at you."
"Do you promise?" Loki asked.
"I promise," Thor answered, "Know that I love you dearly. Now sleep, little brother." He kissed Loki on the forehead and ruffled his hair before returning to his own bed.
After that night, Loki stopped having nightmares.
Many years have passed since then, and Loki is gone.
The day that Loki let go and allowed for himself to fall from the Bifrost, disappearing into the darkness, was the day that Thor's own nightmares began.
They were tame enough at first. They started as wide, empty expanses of darkness. Once or twice, he could have almost sworn that he'd heard Loki's voice, lost somewhere in that darkness, soft and silky, just like he'd always remembered it. Then, they slowly became chambers of Thor's own personal hell. Night after night, he'd be unable to see Loki, but he could hear him as vividly as if the dream was reality, calling for help, crying out for him, screaming his name. He'd grope blindly through the darkness, sure that his beloved little brother was lost, in danger, hurt, or even dying. And every time in those nightmares, he'd be too late. He'd find Loki's lifeless form, pale as snow and cold as ice to the touch, emerald eyes still frozen wide open in silent agony. A trail of blood would always be winding about his body, and then Thor would look down, and much to his horror, see his own hands stained crimson with blood – though he was never sure whose blood it was.
He would wake up crying out Loki's name, body shaking violently and covered in cold sweat.
No matter what Loki had done to him and to Asgard, he was still Thor's precious baby brother, and Thor could not forgive himself for what had happened on the Bifrost, nor could he bring himself to fight or lift a hand to harm that baby brother who he had sworn to protect, even if he was now his enemy.
When Thor looks at Loki now, he thinks he can still see that wide-eyed child who had so often been haunted by nightmares and all along, had only needed the love and protection of his big brother.
Thor can't help but think perhaps he'd failed Loki in that way. Maybe that's why they're here now, the city around them burning, the air stinking of death and destruction. Maybe that's why Loki is glaring at him with such venomously frigid hatred that he feels like his heart is being seared open. Maybe that's why Loki's hands are dark with Thor's blood. Maybe that's why Thor, for the first time, feels like crying.
"You promised," Loki hisses, his voice trembling with such an air of betrayal that it sends waves of agony through Thor's chest, "You promised you'd protect me from the monsters. You said you'd slay them."
Out of the corner of his eye, Thor sees Tony Stark move forward, but Thor holds out a hand, and Steve Rogers pulls Tony back by the arm. He knows that this is a matter between the two brothers only.
"I am sorry, Loki," Thor manages to say, "I'm sorry about everything. Whatever it is that I've done to you, I'm sorry."
"Shut up, I don't want your apologies, brother," Loki says, spitting out the last word like it is a filthy curse that should never be uttered, "You never kept your promise, and you dare think that a mere apology is all that you need to placate me."
"Loki, please. I don't know what you're talking about."
"Don't you see, Thor!" Loki screams, voice hoarse and breathing ragged, "I'm the monster, you fool!"
Thor looks at Loki, and although Loki's face is twisted with a fiery rage, he can still see desperation in his eyes, which he dares to think are not as cold as he remembers anymore. While the other Avengers may see a lunatic, a madman consumed with greed and jealousy, all Thor sees is his little brother, who he loves more dearly than anything else in the world, lost and tormented by demons in the night, needing nothing more than his big brother at his side.
Thor shakes his head. "You're no monster. You're my brother."
"How dare you act as if you understand me, Thor?"
"Perhaps I don't, but I understand well enough to know that you're not a monster."
"I am!" Loki cries, nearly hysterical at this point. "I'm the hideous Frost Giant from those dreams I had as a child, too stupid to know what they meant. I'm the monster that kills you, Thor, and I will be my own undoing as well! So do it! Slay me!"
"I will not harm you, brother!" Thor roars back, and he feels an indescribable feeling explode from his every pore of his body, potent and powerful – anger, frustration, and most of all, love. His entire body shakes, his heart thundering in his chest as the feeling rushes through his veins, filling his entire being with the white-hot sensation.
"You are a coward," Loki says viciously, gesturing to the wreckage around them, "Look at us, Thor. This…Everything…It's all over already." His voice wavers and quivers, and Thor's heart breaks, because the look on Loki's face is no longer angry, but utterly lost. "I never wanted for any of this to happen. You know what you must do. Save your beloved Midgard from your monster of a brother and be done with it, before I destroy us both."
"It's not the only way," Thor murmurs, "It cannot be." He reaches out for Loki, and his fingers brush against his brother's cold cheek. Loki recoils from his touch.
"It is, whether you want it to be or not. Long has my mind been plagued and possessed by evils that would break the soul of even you, the mighty Thor, pride of Asgard. I am no longer the brother you knew, and I never will be again. I hardly even know myself anymore. You made a promise to me, and so you must do this for me, Thor. For both of us."
"I will not."
Loki is silent. He looks at Thor, studying him. His eyes are eerily calm and resolute as he grips his spear tightly in his shaking hands.
"Then I will."
Thor lunges forward desperately, but he is too late. Loki thrusts the spear through his own abdomen, and their world seems to crumble into pieces around Thor as he screams out his brother's name.
Loki makes no sound of pain as his knees buckle beneath him, the spear clattering to the ground as he collapses with an eerie gracefulness. Thor is at his side in an instant, and he has his brother gathered up in his arms, holding him tightly to his chest, as if his grip alone can stop him from slipping away forever.
"Brother," Loki rasps. His breathing is faint and uneven and sounds like a death rattle. Blood pools at the corners of his lips before leaking outwards in rivulets, leaving long crimson trails down his jawline, stark against the porcelain flesh. Thor can feel blood on his hands too, soaking through Loki's garments. He looks down and sees that Loki has sliced himself open, entrails spilling from the gaping wound. The once glimmering emerald eyes are dulling rapidly as he struggles to draw breath. He doesn't have much time left.
Thor clasps Loki's shaking hands in his own. They are ice-cold. A tear rolls down Loki's cheek as he trembles in Thor's hold.
"I am sorry, Thor," he gasps out, "So…very sorry. I shall never forget your kindness." His heartbeat is faint now, and Thor knows it will soon stop entirely.
"You have nothing to be sorry for," Thor answers, and he tenderly brushes away Loki's tears with the back of his hand. Now, after all these years, it is oddly comforting to have his dear brother in his arms once again, to be able to chase away his nightmares for good.
They are children once more.
Loki coughs again, and Thor's hold around him tightens instinctively.
"Know that I love you dearly," Thor whispers, and he presses a kiss to Loki's forehead, "Now sleep, little brother."
Loki smiles softly, something Thor has not seen in years. Content, his dark lashes flutter for a moment before his eyes close, and his body goes still in Thor's arms. In that moment, he looks so peaceful, so innocent, so much like the sweet child he had once been. Thor cradles Loki's lifeless form to his chest, and holds on to him as tightly as he can. He doesn't know how long he stays like that. It could have been hours, days, weeks, or even years, for all he knows, but he doesn't care.
There comes a time when he has to let go of Loki, and although he is reluctant to do so, he knows that must.
He must do it for himself. For Loki. For both of them.
And the day that he finally does, his nightmares stop.