**I.**
The training continued in much the same shape for the rest of that week, small sessions, small increments, the limit shifting a little further each day exactly as Suzu had promised it would, and it was on the evening the week closed that Hikaru finally returned, travel worn and quieter than usual, from the mission that had kept him away since before Muzan's training had even begun.
He found Suzu in the study, the same room that had hosted every one of Muzan's lessons that week, scrolls still scattered in their careful, deliberate disorder across the floor.
"You're back." Something in her whole posture eased at the sight of him, relief she didn't bother disguising. "I heard fragments, nothing complete. Are you all right?"
"I'm well," he said, before she could finish asking. "Tired, more than I'd like to admit, but well." He settled onto the cushion across from her with the particular careful slowness of a man whose body was only now allowing itself to feel the full weight of the week behind it. "You should hear the rest of it properly, before I let myself think about anything easier."
He told her plainly, the way he told most things, without softening the parts that deserved to stay unsoftened. The salt caves, the fifteen survivors found chained more by exhaustion than by anything physical, the children among them too quiet in a way children were never meant to be. The matriarch, Sumire, found half dead in the field before that, fighting a battle she had no real chance of winning alone and fighting it anyway, because there had been no one else left standing to fight it in her place. The slow, careful journey home, and the offer Butsuma had made her once she was strong enough to hear it, an alliance, not a surrender, terms she'd accepted with her spine still straight despite everything that had been done to break it.
"Fifteen people," Suzu said quietly, once he'd finished, "out of five hundred."
"Fifteen more than the Kemuri intended to leave standing," Hikaru said. "I told her much the same thing, when she said it to me first. I'm not certain either of us fully believed it made the number feel like enough. But it was true regardless, and true seemed like the only thing worth offering her in that moment."
Suzu reached across the small distance between them and took his hand, saying nothing for a long moment, simply letting the weight of what he'd carried home with him settle between them instead of asking him to carry it alone any further. "You did well," she said finally. "Whatever it cost you to do it."
"It cost less than staying home and doing nothing would have," Hikaru said, and though his voice stayed even, something behind it suggested the week had asked more of him than he was fully prepared to name aloud that night. He let out a slow breath, and some of the weight visibly eased from his shoulders, as though the simple act of having told her had lightened something he'd been carrying the entire ride home. "But I find I'd rather think of easier things, now that it's told. Tell me about our son. How did the first week go?"
---
**II.**
Suzu's smile answered before her words did. "Better than I dared hope, if I'm honest with you. He took to it faster than I expected, faster than I think even he realized. His limit moved every single day, sometimes twice in a day, and he never once complained about the repetition the way I half expected a boy his age to. If anything, I had to hold him back more often than I had to push him forward."
Some of the road weariness in his shoulders eased further as he listened. "That doesn't entirely surprise me. Tell me the rest."
"There isn't much more to tell yet, not after only a week. But I'll say this much." She hesitated a moment, choosing her words carefully. "Given what he carries, Senju blood from his father, and whatever thread of Uchiha runs through Iori's line however many generations back, I would expect his physical and spiritual energy to sit well above an ordinary talented child's, even accounting for how young he still is. Everything I've seen this week hasn't contradicted that expectation. If anything, it's confirmed it rather plainly."
---
**III.**
Something quiet and unguarded crossed Hikaru's face at that, the look of a father allowing himself, for a moment, the simple pleasure of wondering. "There are three kinds of genius, or so the old instructors used to say when I was young enough to be taught by them," he said, half to Suzu, half to himself. "The first grows slowly, so slowly that most give up on him long before anyone realizes what he's quietly building toward, until one day the ceiling above him turns out to have no visible end at all. The second blooms early and brilliantly, faster than anyone around him, and then, somewhere in his early twenties, simply stops, having reached whatever limit was always going to be his and finding no further room to climb. And the third," and here his voice softened further, something almost wistful in it, "learns quickly, reaches a high plateau faster than either of the others, and then, rather than stopping there the way the second type does, simply keeps climbing past it, year after year, as though the plateau were never really a ceiling at all, only a resting point on the way to something higher."
"Which do you suppose he'll be?" Suzu asked, quiet, genuinely curious.
"I don't know," Hikaru admitted, and there was no frustration in the admission at all, only a kind of warm, patient anticipation. "I find I rather like not knowing. It gives me something to look forward to, watching which one of those three he turns out to be, rather than simply being told the answer today and having nothing left to wonder about." He was quiet a moment, turning something over. "There's a great deal more I'll want to teach him, in time. Chakra and the body are only the beginning of what a shinobi needs to understand to actually survive and matter in this world. Once he's old enough to hold it properly in his mind, I intend to teach him the political landscape myself, the Fire Country's shape, the lords and clans that hold it together or threaten to tear it apart, the way alliances are built and spent and sometimes betrayed. That's knowledge no scroll teaches nearly as well as someone who's lived inside it can."
"He has time yet for that," Suzu said, gently. "Let him have his chakra and his hand seals first. The rest of the world will still be there waiting for him when he's ready to understand it."
"It will," Hikaru agreed, and for the first time since he'd walked through the door that evening, something in him finally, fully relaxed. "I'm in no hurry. I find, watching him, that I've become a rather patient man these last five years, whatever else I might have been before them."