Senjuro's age: 12
Kyojuro had achieved the rank of Hashira, and Senjuro was both prouder than he'd ever been and terrified that someday soon he would receive a crow that said his brother had died in battle. Though being a Hashira meant Kyojuro was now one of the most powerful Demon Slayers, it also meant he was now in far more danger. Rather than facing just any demons - which was dangerous enough - he'd regularly be fighting some of the strongest demons in existence. He might even have to face Upper Moons. His wounds had been bad enough after his fight with Lower Moon Two and Senjuro shuddered to think of the damage an Upper Ranker might be capable of inflicting.
He sighed as he watched Kyojuro run through some katas in the yard. Kyojuro seemed untouchable now, but he knew all too well that that wasn't really the case.
A flash of black feathers caught his eye; he gasped as a crow swooped into the yard. "Kyojuro Rengoku! Kyojuro Rengoku!" the bird cawed as it circled the yard. "Report to Ubuyashiki Manor for your official appointment as Flame Hashira!"
"Oh!" Kyojuro said, dropping his stance. "All right! I'll be there shortly!" He waved to the crow, then started jogging toward the house.
Senjuro followed him into the training dojo, where he was returning the practice sword. "Um, brother…?"
"Yes?"
"Now that you're a Hashira…" What was he doing? He couldn't ask Kyojuro not to take more dangerous missions. He certainly couldn't ask Kyojuro to prioritize himself over the civilians. But he couldn't bear to watch his brother go to accept a position that would almost certainly end in death. Not without imploring, even if it was futile, that Kyojuro be careful. "I know you can't guarantee it," he continued, "but please…be careful. Please - please try not to…" He couldn't finish the sentence. The thought of Kyojuro dead made him feel like he was suffocating.
And if Kyojuro died, he couldn't shake the thought that it would be partially his fault. He was supposed to be a Demon Slayer too; he was supposed to have Kyojuro's back. But because Senjuro could barely use Flame Breathing, Kyojuro would be going into this alone. Because Senjuro was too weak to help him.
Kyojuro tilted his head and stepped closer. "Senjuro—" he started.
"No, I know," Senjuro shook his head. "You need to do whatever it takes to protect people."
"That's true," he agreed, "and it carries a risk I'm willing to take." His tone was completely serious in a way Senjuro almost never heard from him. "That doesn't mean I won't fight my hardest to always make it home. That will always be my second priority."
"But it can't be your first."
"No," he conceded. "There are too many lives at stake."
"I know," Senjuro admitted. Tears stung his eyes and he sniffled, trying to hold them back. It wasn't right that he was getting this upset about the most basic fact of Kyojuro's job: being a Demon Slayer meant Kyojuro could die on any mission at any time.
"Don't cry, Little Flame," Kyojuro murmured, wiping away a lone tear that had leaked down Senjuro's cheek. "I'm still here. And who knows - maybe we'll defeat Muzan before you even finish your training."
He knew Kyojuro was trying to reassure him about a situation where reassurance was almost totally pointless, and he had to appreciate the effort. So he nodded and allowed Kyojuro to pull him into a tight hug, hoping with all his heart that this embrace wouldn't be their last.