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Diluc led the forces of Mondstadt onto the battlefield, entering the legions into attack position as the army of Khaenri’ah advanced on the other side. He squinted through the early morning mist and haze of smoke as the ruins around him burned, trying to make out individual people in the advancing battalion. He had heard there had been a few betrayals, people jumping ship to fight for Khaenri’ah. If he could, he would take them out first.
As soon as the Mondstadt legions had properly arranged themselves, Diluc and Jean ordered them forward, advancing on the Khaenri’ah troops. The leaders were beginning to come into focus, and Diluc noted flecks of deep blue and platinum blond hair on the two front runners. Good, easy targets to pick out in the crowd, he thought. They were close enough now to engage in combat, and at his signal, the archers began firing. He advanced with the swordsmen on foot while Jean broke off and advanced with the cavalry. The blue haired leader broke off to match Diluc’s group and the two charged at each other, the sides locking in a fierce sword fight.
Raising his claymore, Diluc moved to engage the blue haired leader, but stopped short when mismatched pale lilac eyes with star pupils looked back at him. He stood frozen as he took in the sight of his estranged brother, the royal Khaenri’ahn uniform he wore, the glow of the eye he had always hidden behind an eyepatch, the royal circlet on his head.
“Hello, Diluc,” Kaeya called, waving. “A shame we’re on opposite sides, we always did make a wonderful team.” Diluc tightened his grip on his claymore.
“You bastard,” he grit out. “After everything we did for you, after you spent years protecting Mondstadt, you jump ship just like that? What did you do to trick them into letting you lead them, you filthy little traitor.” Kaeya, to Diluc’s chagrin, only laughed at this.
“Come now, Diluc, do you really think so little of me that I would have to trick my own people into letting me lead? I’ve always been their leader, the royal prince of the fallen crown. My people wholeheartedly embraced me when I came back brimming with secrets of our enemies,” Kaeya responded as he cut down a Mondstadt soldier with ease. Diluc grit his teeth, slashing at the Khaenri’ahn soldiers that were beginning to flank him. Kaeya smiled and gave a sad little wave, melting into the battle around them. Try as he might, Diluc couldn’t reach the resurfaced prince, so he settled for destroying as many of the enemy soldiers he could.
The battle continued on well past nightfall, until the soldiers on both sides could barely stand. Jean and Diluc ordered a retreat back to camp as Kaeya and his boyfriend did the same. Jean pulled him up onto her horse and he laid his head wearily on her shoulder. Closing his eyes, he allowed his fatigue to take over, and he slowly slipped into unconsciousness.
He awoke some time later to Jean shaking him awake.
“Rise and shine sir-I mean-Diluc. We have to prepare the troops,” Jean said, continuing to shake him. Diluc groaned and sat up.
“What do we need to do?”
“Regroup and recap what happened yesterday.” Jean walked out of his tent, reminding him again to get up.
Five minutes later saw Diluc running a hand through his messy hair as he listened to Jean’s recount of her team’s fight. Finishing her report, everyone’s eyes turned to Diluc, who sighed heavily.
“Kaeya’s our opposing leader,” he said simply. The assembly sucked in a collective breath. “If I can catch him on our own, I can put him down. Then it’ll be easy to win.” He said it so matter of factly that most of the people assembled found themselves nodding along. Jean, however, frowned.
“Diluc he’s your brother. You don’t need to shoulder that burden,” she protested.
“No brother of mine would be leading the Khaenri’ahn army,” Diluc responded flatly, leaving no more room for discussion.
* * *
Setting foot on the grounds of the Dawn Winery, Diluc stretched, heading for the front door. He hadn’t spoken to Kaeya since the first battle, but he knew he’d be here. Both brothers knew that one wouldn’t walk away from this, and neither particularly wanted the battle to be witnessed by others.
Reaching the stone patio surrounding the manor, Diluc took note of the blue haired figure, still wearing the royal colours of Khaenri’ah. Diluc wrinkled his nose, clearing his throat to get Kaeya’s attention. Kaeya turned, donning his signature smirk.
“Master Diluc,” he greeted, sauntering towards Diluc. Diluc grimaced, materializing his claymore out of thin air. “I have no interest in idle chit chat with a traitor,” he ground out. Kaeya had the audacity to look offended.
“I’m hurt, Diluc. And here I was thinking that we might come to a sort of agreement,” Kaeya gave a halfhearted shrug, materializing his sword.
“Like hell you did you bastard,” Diluc spat, swinging his claymore at his former brother. Kaeya parried it, causing Diluc to note that even his sword had the royal insignia of Khaenri’ah on the pommel instead of the Favonius inscription his old sword held.
As the battle between the two waged on, the first drops of rain began to fall. Diluc paused for just a moment to admire how fitting it was. It had been raining the night the brothers had parted ways, and it would be raining the night one brother departed to Celestia. Kaeya quickly forced him out of his thoughts, however, as he was forced to block a blow that would have been fatal without his quick reflexes. So thus they continued their deadly dance, fire against ice, sword against sword, brother against brother.
The sun had long set behind the clouds when Diluc finally found an opening in Kaeya’s defence and swiftly knocked his sword out of his hands. Instinctively, Kaeya threw up an ice shield, similar to the one that appeared the night he had gotten his vision. This time, though, Diluc was prepared, and sent a flaming Dawn phoenix to melt the ice. A quick slice to the stomach and Kaeya was on the ground, staining the flagstones red with blood. Seemingly in a trance, Kaeya brought a hand up to his stomach, as if to try to stop the flow of blood. The reality of what he had just done suddenly hit Diluc, and he dropped his greatsword with a thud, kneeling down to cradle Kaeya’s head in his lap.
Kaeya looked up at Diluc with a sudden clarity in his eyes, and Diluc realized in horror that Kaeya hadn’t been in a clear state of mind since Crepus had died. Almost as if corruption and abyssal magic had—with dawning horror, Diluc frantically tried to apply pressure to the gaping wound in his brother's stomach, but was stopped by Kaeya’s hand.
“D-don’t,” Kaeya stuttered, choking as blood oozed out of his mouth. “Th-they’ll just control me again if I stay alive. I-t’s better thi-is way.” Diluc shook his head hysterically.
“No, no Kaeya please, we can save you, we can-we can get help and we can stop them together!” But even as the words left his mouth Diluc knew it was too late to get help. Even if the staff had still been in the Winery, there wouldn’t have been time. Diluc found Kaeya’s hand, holding it tightly while his other hand cradled his head delicately. Kaeya gave him a soft smile, turning his head to the side as he coughed up more blood. Diluc tried his hardest to ignore the growing puddle of blood haloing them.
“Remember when we collected seashells that time father took us to Liyue?” Diluc asked softly.
“And you tipped the bucket over when you tripped. We spent so long picking them all back up,” Kaeya responded with a raspy laugh.
“Father was so exasperated that we were soaked to the bone, I think he went through the five stages of grief in five seconds,” Diluc laughed.
“We should do it again sometime,” Kaeya said wistfully, and Diluc wiped at the trail of blood at the corner of his mouth.
“Yeah, next summer we’ll go, and it’ll be a competition, see who can get more shells,” Diluc ignored the tears dripping down his face.
“Look, Luc, it’s snowing,” Kaeya exclaimed, raising a shaking hand to point at the sky. Diluc looked up, and sure enough, big white flakes were beginning to fall from the sky. When he looked back at Kaeya, the fluffy flakes were nestling in his blue hair as he shivered. Diluc took off his coat, placing it over Kaeya’s body.
Kaeya coughed blood and smiled at Diluc, “Always the caring brother, huh Luc?”
“I’m sorry, Kae, I should have been here for you all these years,” Diluc whispered. Kaeya raised a shaking hand up to touch Diluc’s face.
“It’s okay. You were here when it counted, thank you,” his lips were turning blue and the light in his eyes was fading fast.
“I love you Kae,” Diluc whispered, tears dripping down his face more frequently.
“I love you Luc, my brother…” Kaeya’s hand dropped as the final light faded from his eyes and he took his final breath. Diluc bent over his brother’s body, not bothering to hold back his sobs anymore. Through the blur of his tears, his brother’s face morphed into Crepus’s as he lay dead in Diluc’s arms. But he blinked and it was his brother’s face again, pale and lifeless as the warmth quickly left his body.
* * *
The battle with Khaenri’ah had ended quickly after the death of their prince. Overcome with grief, the prince’s boyfriend died soon after, leaving the Khaenri’ahn army in disarray, allowing Mondstadt a quick victory. No one bothered Diluc much, in fact people scrambled out of his way when he walked by. He didn’t really care, there was no one who would be able to console him, and no one who he wanted to talk to.
When he returned to Mondstadt, he left the Winery in Elzer and Adeline’s hands. He didn’t stay long, packing his things and moving away from Mondstadt permanently. He returned once a month to reassure Jean he was alive, and to tend to the two graves in the back of the church. He had no family left, and no reason to stay. Looking up at Celestia at night, he sent up a silent prayer to any god who would listen in hopes his father and brother were happy there, and a silent promise that he would one day see them again.