Shisui is tired. Shisui is tired of unspoken tiredness. Shisui is above all tired of how Itachi isn't. "Really, it's dawn. Cousin, you can't be a night owl all the time. It's not good for you."
"Your concern is registered," Itachi says from where he is sharpening shuriken, careful with the edges in his hands and careless of those in his lap.
"Cousin." Shisui sighs and tries not to think about how many shuriken Itachi's sharpened lately, how many more there will be to sharpen. Every tool is a casualty of war, graveyards embedded in bark and bone. Every one of them lines Itachi's eyes. "You need to sleep. You have to sleep."
"Will you force me, cousin?"
Cousin is a barb; it is an endearment in its sarcasm. Why should they be cousins? Why shouldn't they? It is not as though Shisui will ever be Fugaku's son. It is not as though that stops him from trying.
It's wartime. They are all Uchiha sons, and like all good little Uchihas, they die in the muck self-blinded as a final act of goodwill for an unloving village.
Shisui is so tired. He can't force Itachi. Itachi can be ordered, but that's all there is, and pulling rank now is a bad precedent later. He'd rather his baby genius mind followed Captain's orders on the field. Rather than, say, deciding that his sister vomiting on a handy corpse is the perfect time to start running into enemy lines as payback for pulling rank off-field. Shisui had to order his team to stand down so their heads could cool and his baby cousin could come back with the scroll they were there to steal.
Itachi stared at him all through the desperate flee back to Konoha, smug unapologetic condescension.
What else could he expect from his rotten little cousin, indeed. Everything is about retribution for him. Everything. Itachi doesn't even bother to call it justice.
It's a pity, really, that his sister fell with self-blinded eyes like a good little Uchiha. Shisui liked her, sure enough, but she was so fucking malleably blank with being the eldest child of a clan head that didn't want her silly feminine ways, murdered and replaced her for a son that drowned in a puddle at four months old.
Itachi loving her so much makes so much fucking sense in retrospect, and Shisui curses himself for being oblivious.
He's so tired.
"Five year olds shouldn't be sharpening shuriken til dawn," Shisui says.
"Fathers shouldn't be waiting on whether to murder their children."
Shisui winces. The issue of Sasuke is a sore point, particularly with ink not even on the parchments declaring an end to the war with Iwa. Mikoto was injured in battle, and Fugaku is so much harsher in the absence of war, not quite knowing what to do without a threat or dozen, and the combination bodes ill for an infant.
Mikoto hadn't wanted another child, wasn't in condition for it, but somehow she was giving birth now, barely declared healthy, and the halls had the air of Fugaku's angry waiting.
They are given the news by a clan elder a little past noon, sliding the door to their room with a pointed cough at Itachi's slumbering curl in the bed, Shisui's jittery sprawl on the floor.
Itachi wakes, watchful, and Shisui stays decorously silent, biting his tongue until it swells in his mouth. "The child has potential for Sharigan," the elder announces. "It is in good condition. We shall name it within the year."
"His name is Sasuke," Itachi says.
The elder frowns. "Don't get your hopes up, boy. The babe is such a little thing. Your mother's too old for childbirth. You ought to take a bride of your own. Keep the blood flowing."
Itachi closes his eyes, relaxes his hands, opens them with the shadows of Sharingan. Shisui knows, in that look, that Itachi will never marry. "How is my mother?"
The elder dismisses him with a snort. "Well enough."
Shisui feels the weight of the hatred that simmers around Itachi, staring calm and narrow-eyed at the screen door, and it disturbs him. Killing intent isn't unheard of in children raised by war. But this focused desire to maim and decapitate is something he wasn't sure Itachi was capable of. Yet. War fosters depersonalised hatred; this is personal.
Too personal.
Shisui watches Itachi take Sasuke into his arms, crying and ugly, watches him blink at the fragility of this trusting little thing.
This living little thing that is one of his, not the enemy's child requiring snapped fragile spines as part of the war effort, but his.
Itachi has never had anything that is his before.
Sasuke, baby Sasuke with his matted cowlick and angry pout, and Shisui watches Itachi's resolve harden, watches the smile spread into the corners of his eyes in chilling decision, and knows that Itachi has declared war.
And Shisui is the enemy's child.