Fili knew his role in this battle.
The same as his role in life.
Big brother.
Winning would be a bonus. Fili was fighting to keep his little brother safe.
The brothers had fought side by side or back to back throughout the entire battle, just as they had their entire life. He remembered something his mother had said once, when his father died all those years ago, that he had "died as he lived". We fight as we live. Side by side. Together. Always.
And then an orc attacked Fili, and he was separated from Kili. Not intentionally. The orc backed him into a corner, and after several minutes of one-on-one fighting, Fili could feel himself begin to tire. Still, all the time, at the back of his mind- Get back to Kili, you must, hurry, as fast as you can, get back to Kili, little brother, stay with him, protect him-
And then Kili screamed in agony. The sound of his brother's hurt ripped through Fili's soul, paining him far more than a thousand orc arrows. He turned, and saw his brother, blood running freely from a wound in his shoulder.
"KILI!" he screamed, and his brother looked up at him. Fili saw the silent plea in the young dwarf's dark eyes.
Brother….
Before Fili could move, he felt a fire of agony in his side. Gasping for breath, he looked down to see an arrow sticking out of his left side. No… the pain was fire running through his blood, the pain was torture, he wanted to scream and scream and scream, he wanted the pain gone…. With an enormous effort, he turned back to see Kili collapse on the ground.
"NOOOO!" With an inhuman yell, Fili killed his attacker and raced to his brother's side, all pain forgotten. Kili, no, please, not Kili, please, not Kili, I can protect him, let me protect him, I promised, please, no, not Kili….
Fili collapsed at his brother's side, no longer able to hold himself up. "Kili," he whispered. Covered in blood, his younger brother lay completely still on the ground. "Kili, please, wake up." Tears trickled down Fili's face. The pain of his wounds was nothing compared to this. "Kili," he sobbed. "Wake up. Don't leave me here alone…"
Slowly the dwarf's eyes flickered open. Kili's dark eyes met his older brother's and he gripped Fili's hand, hard, and looked at him with eyes full of trust. "Fili…" he breathed.
"I'm here," Fili said. "Kili, I'm here."
"Stay with me, brother," he choked, struggling for breath.
"I will stay with you, Kili," Fili whispered. "I will never let you go alone. I will always be with you, brother… always."
The faintest trace of a smile touched Kili's lips, and then, with one last shuddering breath, the young dwarf closed his eyes for the last time.
I will never let you go alone. Blinking back tears, Fili gave up his struggle, and, closing his eyes, let his last sleep overtake him.
The brothers died as they lived. Together. Forever.
I will never let you go alone, brother.