A/N: This is the first fanfic I've written in about two years so I don't really know how good it is, but I figured it was about time I got back to writing, and what better way to do that than with some angst.
In seventy-seven years of life, Kili had never given more than one or two passing moments worth of thought to the idea that he could one day be king, for there had never been any reason to give it more than that; after all, it was Fili who was Crown Prince, not him. It was Fili who received the focus of Balin, Dwalin, and their Uncle's training; Fili who had to sit for hours and listen lectures on politics and just what it meant to be a ruler; it was Fili who would occasionally accompany their Uncle to council meetings; and it was Fili, who one day when their Uncle had grown old and gone to his rest, that would take his place as their people's next ruler.
Not of course that Kili himself hadn't had his own fair share of training and lessons, no Heir of Durin would be allowed to get away without them after all, but he was firm in his belief that most of them would never be put to any use. After all, the only way the mantle of King could ever come to be placed on his shoulders would be for both Thorin and Fili to die first, and that was never going to happen.
Not that he was so naive as to think his uncle would live forever, dwarves didn't have the immortality of the elves after all, but he knew without a doubt that Fili would never die and leave him behind. They were brothers after all, with such a closeness that, despite their contrasting appearances, there had been many a stranger who mistook the two of them for twins; you did not have one without the other. From the time that Kili was born, there was seldom a time when the two of them were apart for very long, and when it did happen it was always with great distress. There was no way the two of them could ever be separated even by death, when the day came that they drew their last breaths, it would be together. That was a fact that Kili had full confidence in.
How easily that confidence was shattered by a sword through his brother and the thud of a dead body on the snowy ground in front of him. As his brother's corpse stared up at him with now lifeless eyes, all Kili could think was how this all had to be some kind of horrible joke, how at any moment Fili had to get up and smile at him and explain that it had just been some ill thought out prank, and that really, he was fine. Because there was no way his brother could really be dead, there was no way Fili would ever leave him behind, right?
Fili didn't get up though, he just lay there unmoving, and Kili suddenly found himself filled with a seemingly endless sense of despair and anger. He'd known Azog was a cruel creature, but until that moment, until his brother's corpse lay before him, he didn't think he'd realize just how very cruel he really was.
Fili had been Kili's everything; his brother, his playmate; and sometimes, despite there being a mere five years between them, a father figure. No matter what he'd always been there for him; whenever he'd gotten himself hurt as a dwarfling, or in trouble from their mother, or yelled at by their uncle, whenever things had been hard and scary, Fili had always been there to comfort and protect him. It was Fili who had come home from his lessons and shared what he'd learned with Kili, even when everyone else had said he was too young to understand; it was Fili who'd supported and encouraged him in learning archery, even when everyone else was against it; it was Fili who'd comforted him about his lack of beard and defended him from teasing about it; it was Fili who'd comforted him and made sure he was okay, despite his own injuries, the first time they'd faced orcs; and it was Fili who'd begged their uncle to let Kili come with them despite his age, to not leave him behind in Ered Luin.
Fili alone had known so many secrets about him, things that nobody else knew; like how he wasn't as naive and stupid as people tended to assume, or how so many of his antics were an attempt to make his brother laugh and forget his responsibilities for a moment, or how much he craved their uncle's approval and yet feared he'd never measure up in his eyes. And he'd known just as many secrets about Fili, his brother had been his confident and he his; they were a pair, always Fili and Kili, never just Fili or just Kili. That was the way it was supposed to be, and without his brother by his side, he didn't think he could bear life, for it would really be living.
'No,' He thought, his eyes drifting from his brother's corpse to the stairs, and then back to his brother again. 'It wouldn't be living it all." For while his body might still physically be alive, the truth was that from the moment Fili had died, Kili had as well. Part of his soul had been ripped out and crushed, leaving a gaping hole that nothing could fill.
Soon, he was sure he would be joining his brother in the Halls of Mahal, but before that happened he wanted revenge, he wanted to take as many orcs with him as he possibly could.
Letting his hand drift slowly to the sword at his side, he took a moment to glance down at where his Uncle still stood with Dwalin and Bilbo, noting the expression of anguish and horror on his face. For a moment their eyes met and he watched the expression change to one of fear as he took in Kili's grip on his sword and the determined expression on his face. He watched as Thorin opened his mouth and shouted something, but whether because of the distance or the haze that seemed to have settled over his mind, the words never reached Kili's ears.
'I'm sorry Uncle,' He thought in silent apology as he drew his sword and let his feet carry him towards the stairs, 'I know I'm being selfish, you've already lost so much, you shouldn't have to lose both your nephews as well, especially not on the same day. I can't do it though, I can't continue on without Fili by my side.' It would be hard for Thorin, Kili knew, especially when he had to break the news to their mother; and surely a good heir wouldn't do this, they wouldn't charge in recklessly with the intent of seeking death, but he supposed he'd never really been a good heir to begin with. He'd just been Kili.
Thorin would make it through though, he'd survive the battle and he'd be King Under the Mountain like he was always meant to be; and with at least a good hundred years of life left to him, his uncle could easily find a wife and have heirs of his own. Heirs who hopefully would never know hardship or war, heirs who could grow up safe and happy within Erebor, never knowing any other home but the one that was rightfully theirs. And Thorin could tell his children tells of the cousins they never got to meet, stories of the happy times and all the trouble they got into, and through those stories they would never really die.
Of course, deep in Kili's heart he knew that their uncle would rather have the two of them alive, nothing and no one could truly replace a lost loved one after all, but he couldn't see any other path to take. Just like he couldn't bring his brother back to life, Kili also couldn't heal the hole that now existed in his heart, nothing but his brother could do that. So just like his brother had left him behind, he would now be leaving his Uncle and King behind as well.
'At least' He though, reaching his first orc and blocking a blow aimed at his head, 'At least he'll know I died fighting and not with a sword in my back. At least he'll know I'm with my brother.' As his sword swung down, cleanly slicing his enemy in half and splattering black blood on the ground, he found himself smiling at that last thought.
"Wait for me Fili." He whispered, moving to the next opponent, "I'll see you again soon."