This is the response to a prompt I got from . I don't know if this is what you expected, but... it happened this way. My stories do that.
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Thor had learned by now that if he didn't want to be found, his brother wouldn't be found. Not even Heimdall was able to spot him when Loki did not feel like it. Their relationship had become less hostile in the last twenty or thirty years: Loki had long since ceased to attack the Avengers and sometimes, he had even worked with them, even if it was begrudgingly and in rare occasions. With the mage's assistance, they had managed to defeat everyone, even Thanos. That was almost fifteen years ago now and Loki had kept to himself.
Mostly.
Sometimes, he still underestimated his elder brother though. Or maybe, he just overestimated Anthony Stark's ability to keep secrets. However, the tentative, hesitantly building relationship between the two – first filled with animosity and spiteful words, later with mutual respect and later on, the burning passion that only beings as short-lived as humans were able to pour into their actions – had not slipped Thor's notice. Neither had the dark-haired woman at the mortal's funeral who had watched the event with an unmoving expression, hadn't said a word and disappeared as soon as the main ceremony was over.
The thunderer found his brother four hours later at a lake's shore, sitting and leaning back against a tree, staring up into the clouded sky. A thin layer of snow was covering his shoulders and apart from the slight raise and fall of his chest, nothing indicated that it was indeed a living being sitting there.
Thor approached him slowly, not really bothering to be quiet; Loki must have noticed him before he had even arrived, anyway. The younger prince did not react, he just kept staring at the clouds and occasionally blinking when snowflakes tumbled into his eyes. Some were nestled in his black hair and his eyelashes.
With a sigh, Thor leaned against the tree heavily, shaking its branches. It caused a heap of snow to fall down, some of it onto Loki. Only then, the younger god glanced at his brother with clouded green eyes. He wiped the snow off of his face and remarked: "Subtle as ever, brother." The comment caused Thor a sharp stab of pain – never before had he heard the younger god's voice sound so dull, so lifeless, so devoid of the biting humour that his remark would have needed to sound as spiteful as it was intended to.
He sat down beside Loki, who was staring at the sky again, and for a while, there was silence between them. The thunderer broke it with an uncharacteristically softly spoken question: "How are you feeling?"
Loki gritted his teeth and whispered: "Don't." He swallowed. "Please don't make me talk about it. It is bad enough as it is, but I..." His voice sounded strangled and he bit out a quiet curse. "Please. I really cannot talk." He pressed the back of his hand to his mouth and stared at the sky, tears gathering in his eyes, and whispered a strained "Damn it, Thor".
"It was to be expected", the blond said quietly, fully aware that it wasn't really consoling. "He was..."
"Mortal, I know, I am not stupid, Thor", Loki cut in, half angry, half choked with tears. "But they... they usually live longer, don't they? I- I mean, he... not even eight decades, Thor. He- he was practically a child. My little boys are older than him and he is- he just- I practically just met him and now..." A wrecked sob cut him off and he pulled his knees to his to his chest, curling up as tightly as he could. "Oh, now you did it, great", he forced out between two choked gasps. "This is why I didn't want to talk."
Humans tended to think that Aesir weren't afraid of death because of their longevity and strength. The opposite was the case though: Death was a rare occurrence, something barely ever witnessed, and therefore far less common and normal than among humans. Death was something even Aesir couldn't recover from, and if it didn't make them fear it, then it at least ensured that it was something they respected.
Thor knelt down beside his brother – it had been ages since he had last seen him this insecure and the fact that the mage didn't even care about his pride enough to just teleport away as soon as he felt his brother approach spoke volumes – and hesitantly reached out to put a hand on the younger god's shoulder. To his surprise, Loki leaned into the touch, another muffled sob escaping him, and Thor wrapped his arms around his little brother who let it happen without offering resistance.
"I should never have come back here", Loki gritted out, wiping his eyes with his sleeve in a vain attempt to keep his face free from tears. "Only three decades." He leaned against Thor's chest heavily. "It's not worth the pain."
"Do you really believe that?", the blond asked. His younger brother didn't reply, but began to draw patterns in the snow with a single finger. Just to fill the silence that the falling snow created, weighing down heavily on both of them, Thor continued: "Jane is sick, too. She has not left the bed in weeks."
"Isn't she even younger than Anthony was?", the other asked quietly, his voice a bit more stable than before.
Thor nodded, knowing that the younger prince would feel it, and explained: "She is, indeed. But apparently the humans can inherit diseases from their ancestors and so she..." He swallowed and tried to calm himself as his voice started to waver.
Loki glanced up at him, his face tear-streaked, and muttered: "Pathetic mortal creatures. Is there anything that does not kill them?" The thunderer bit his lip, feeling his eyes watering at his brother's bitter humour, and Loki immediately reacted: "Oh no, don't you dare, Thor, not you too, stop it!" He shook his head with a sound that was half laugh, half sob. "You cannot cry now, we- this is... look at us, Thor, we're so pathetic." Now it was definitely sobbing, not laughing, and Loki hid his face in the fabric of the other's shirt, curling up against him in a way he had last done when they had been children, terrified of whatever nightmare had disturbed their sleep at the time.
Thor closed his eyes and for a while, he just breathed in and out slowly, hoping that it would calm the younger prince. Empty reassurances wouldn't help, rather make things worse, so he just held Loki and waited for his sorrow to pass.
A mortal's life was over in the blink of an eye – fifty, sixty, eighty or even a hundred years; in the end, it didn't mean anything to someone with a life that lasted millennia. No matter how beautiful the decades spent with a mortal were, in the end, the one who lived longer always lost.
The thunderer wasn't sure how long they had been sitting there when Loki twisted out of his embrace and settled back against the tree, once again staring at the sky. At some point, the snow had ceased to fall and a few patches of pale winter sky shone through the thick, dark clouds. Its colour was lifeless, the sun too far away to grant any real warmth, and sitting in the snow with red-rimmed eyes, Loki made a truly miserable picture.
"Will you come home?", Thor asked when he couldn't stand the silence any longer.
"I am not welcome in Asgard", the mage replied, his voice raw and devoid of any emotions, as if they had left him together with his tears.
"You know that is not true."
This time, Loki took longer to reply, his eyes not leaving the sky for one moment. After minutes of silence, he pushed himself up onto his feet with the help of the tree, brushing the snow off of his clothes before he met Thor's gaze and answered vaguely: "Someday, perhaps. But I cannot- not right now." The blond nodded his understanding and received a nod in return before Loki vanished in a swirl of gold.
He would recover. They had time – more than enough of it; and Thor knew that Loki would learn to deal with it one day, just as Thor would learn to cope with the impending loss of Jane. Both of them had known what would happen when they had their respective relationships and their wounds would mend.
It could take years, yes, but different from their lovers, they could afford to take the time to heal.