Author's notes/disclaimer: Naruto is owned by Masashi Kishimoto. Errrmm this is pure non-massacre trash/crack because Itachi Shinden is killing my heart with the feels. I don't know how that equated with Sasuke being genderbent but here you go. No warnings for right now except for Satsuki's (and Mikoto's) filthy mouth, but eventually there will be fem!GaaSasu, maybe GaaNaruSasu if that's what people want.

Any advice is greatly appreciated, especially on what to do the question of Itachi: to pair or not to pair. I think Izumi is hella cute but so is Shisui. And older!ItaSaku. And basically Itachi x anyone. I need to stop having shipping ADD.

Satsuki is five years old, eyes wide and pitchy-black like those of the baby seals Itachi has seen in the islands of Kiri, when she smiles sweetly and asks her beloved Big Brother the best way to kill a man. Itachi puts down his stick of dango, nods approvingly, and tells her that the best way to kill a man is a senbon to the internal jugular artery in the place where a man's neck meets the underside of his chin.

Satsuki claps her hands delightedly and demands a demonstration on the practice dummies right now. When she thinks Itachi's eyes are off her for a second, she not-so stealthily shoves all of Itachi's dango in her mouth and tries to swallow it. Chubby chipmunk cheeks bulge as Satsuki closes her overflowing mouth. A piece of dango pops out of her mouth and her bottom lip begins to wobble in exaggerated dismay.

Itachi smiles. His precious baby sister really is the most adorable thing in the whole entire village—no the whole entire nation—at this age. In a few years, Satsuki will be the most beautiful thing in all the lands, even more breathtaking than their mother—and all the men for miles around will come flocking. Itachi's smile freezes.

He thinks of his past missions, of strange men and dead bodies and girls just a bit older than Satsuki killing, and of war and a world gone mad just a few years ago. No—not his baby sister. Nothing will ever touch her. No one will hurt her. Ever.

Then, Itachi flicks her on the forehead and says, "Foolish little sister, you don't have to worry about men coming close enough for you to kill them. Remember, Satsuki, men are lustful, filthy beasts that will want nothing than to act upon their baser urges with you when you're older. Never let them touch you, and if they do, castrate them."

Itachi's pacifist tendencies be damned when it comes to his Satsuki. What are big brothers for if not to happily murder anyone that looks at their baby sisters funny?

Satsuki furrows her eyes together but nods dutifully. "Menaspigswhocastwated," she repeated, cheeks puffing out with her mouth still full of food. Sometimes her older brother is so strange. As if she would get close enough to a boy to let them touch her. Everyone knows boys have chakra-draining lice all over them—Papa told her and Papa never lies—and Satsuki is too clever by far to let herself get cooties. And boys smell. This castration thing that Itachi tells her of must be very powerful enough to chase annoyances such as boys away. Filthy beasts, indeed.

When Satsuki recites what her prodigy older brother has taught her at dinner that night, Fugaku nods his head absently and adds that standard greeting if male outside their clan approaches Satsuki is a knee to groin. Mikoto shakes her head resignedly. And she had though Great-Uncle Madara was bad. There is something severely wrong with all the men in their family.

…

Satsuki, age nine-almost-ten, counts to ten in her head as her too-skinny body vibrates somewhere in between poorly concealed rage and grief. Itachi is in pain. Someone has hurt her older brother, made him paler the white sheets of the hospital bed he is trying to escape. And Father—stoic, strong Fugaku—has been left crippled, unable to go out into the field again, and Mother, belly once fat and pregnant, is pregnant no more. Satsuki hears Father's voice worn-down saying, "Satsuki, go to your Brother, go comfort your Brother. I am fine."

But it is not fine. Orochimaru is the cause of that with his creeping tongue and killing aura. He came of her, came for her eyes. This is all her fault, Satsuki thinks.

"Itachi," Satsuki vows, looking straight into Brother's face, "I will avenge you, and Orochimaru will never hurt you or Father or Mother again. He is going to die. I am an avenger."

Itachi—slightly doped up by pain meds and caught up in his own fantasies of happily murdering the man that had the gall to go after his family—nods his head seriously and wonders when Satsuki became so mature, issuing death threats as bright red eyes glare out at imaginary enemies. Not so adorable anymore. That is good. Little sisters should know how to look after themselves. Not that Satsuki will ever have to. Itachi remembers the ultrasound of two twin girls and Mikoto's devastated face as the medic-nin bore her away on a stretcher.

No, no one will hurt Satsuki ever—or Mother or Father. Orochimaru is going to die.

He beckons Satsuki with his hand and pokes her oh-so-lovingly on the forehead. His baby sister is everything that is right with the world. "Don't worry yourself, foolish little sister, why don't you rest? You can think about avenging another time. All this excitement is going to make you overexcite yourself," Itachi says reassuringly.

Satsuki's eyes turn black and her body stills. Poked on the forehead by Itachi. Carelessly ignored as Orochimaru as he advanced towards Mother. Both dismiss her, seeing a little girl and thinking her weak for it. Satsuki rearranges her face into the most placid imitation of a smile she can possibly fake before biting pointed teeth down into Itachi's finger.

Let Big Brother see how overexcited she is now. For a minute Satsuki thinks about how more convenient it would be if Itachi was standing up so she could more easily knee him in the groin; then Satsuki stops herself. If she is going to channel these violent twitchy urges she keeps having, she must never channel them at Brother. There are better targets. Enemies, enemies are good targets.

"Fuck nuggets, 'tachi, Orochimaru is a puss-eating, goatish, hells-hated son of a misbegotten gutter whore, and he is my kill. Don't try to take him from me, Big Brother," Satsuki says in her Tea-Ceremonies-and-Other-Polite-Occasions voice. "Please," she says as an afterthought. Mother always said it was best to be polite before forcing one's opinion upon others.

Aghast, Itachi is thrown back for a second. Then, his mind comprehends what his paragon of perfection has said in her childlike lisp. Cousin Shisui has corrupted her. "S—Satsuki," Itachi says, stuttering for the first time in years, "You shouldn't talk like that. It isn't—"

"Fucking lady-like?" Satsuki injects, face scrunched-up and slim brows furrowed. "But Mother speaks like this all the time when she thinks you or I aren't listening."

Oh, well apparently Satsuki did not get it from wayward cousins then. Itachi is not sure what to say to that.

…

Satsuki, recently graduated, pointedly taps her foot on the floor and places a hand daintily on her hip. These are ways that a proper kunoichi femininely shows her displeasure, or so the Academy teachers taught her. "Composed and aloof in your killing beauty," the textbook had called it. Even when Satsuki thinks her lessons are stupid, she excels at them. She is, after all, an Uchiha clan head's daughter through-and-through. And an avenger.

The pink-haired annoyance and orange-clad imbecile that call themselves her teammates are not, however. Apparently, they do not understand that Satsuki's composure and aloofedness can be equated with killing beauty. They are positively gawking at too-naïve-for-their-own-good Shisui and Itachi as they spar. Her Itachi.

Then, Shisui adds an Exploding Tag to the already-sprung trap and stretches casually, muscles rippling visibly under his shirt. "Hello ladies. Why didn't Satsuki-chan tell us she had such adorable teammates?" Shisui calls out to them with a wink and a laugh. Satsuki's foot stops tapping and her eye twitches.

Sakura, at the very least, has the good grace to blush and attempt to avert her eyes as she leers. Naruko, on the other hand, opens her mouth and—

"Nee, Satsuki-bitch, did you know that your cousin is really hot? Wait, no, your brother is even hotter. Damn. How'd you like me as a future sister-in-law as well as Hokage? Believe it!"

Then, a tan arm is swung around Satsuki's neck and the orange fungus attempts to give her noogie. Satsuki tenses for a second, trying to recite the lessons that were pounded into her head by kunoichi class.

Composed and aloof in your killing beauty. Composed and aloof in your killing beauty. Composed and—

"Fuck this shit," Satsuki grinds out, coming to a decision. After she sets the orange fungus currently growing on her on fire, she will visit the Academy library. Those textbooks do an injustice towards her entire sex, and Satsuki, after all, is an Avenger. That transcends all these stupid things adults say she should be like because of her gender.

…

Itachi watches as Satsuki, age twelve and something close to beautiful, as she spars with Nara Shikaku's only son in an outstanding display of grace and talent and perfection. No one can compare to Itachi's adolescent sister.

Especially not the Kazekage's little redheaded daughter who that keeps on issuing death threats to everyone and their uncle. Itachi cannot wait for Satsuki's fight against her. That Suna-nin with the mask that looks like bargain-bin drapery covering half his face—Baki, yes that is name—is getting uppity and putting absurd amounts of money in the betting pool against Satsuki every round. Itachi will show him. And win 300,000 ryo. Itachi is running slightly low on funds and has been eyeing the perfect shruiken set for Satsuki when she will undoubtedly win the chunin exams.

Suddenly, there is a collective intake of breath from the crowd around Itachi. The Nara has managed to say something upsetting enough for Satsuki use a fire jutsu so powerful that columns of flame dance to the edges of the arena. The Nara is forced from the shadows and into the light .The fight descends to a brawl and the scoundrel actually puts his hands on Satsuki's chest—a clumsy attempt at a punch, not a grope—but to Itachi, it does not matter. This cannot stand.

While Itachi is not usually one to judge someone before knowing them for at least long enough to inquire about their thoughts on the local sweets shop—such things are important in judging a man's true self—he can tell that this Shikamaru character is no good. Itachi could even say that this boy is representative of the general delinquency all boys in Satsuki's age group. But none of the other boys have the gall to attempt to flirt with Itachi's little sister in front of him. In fact, all of the other boys in Satsuki's age group seemed rather fearful of her after that one instance Satsuki asked Iruka-sensei the best way to castrate the Inuzaka punk after his dog got into her lunch box. Itachi takes this as a sign as their complete lack of taste. Shisui, the dunce, says it is a sign of their wisdom.

This Nara boy is now flirting and calling Satsuki a "troublesome, overly aggressive wench" as they grapple in the dirt. Itachi wasn't born yesterday; he, as well as the rest of Konoha, know very well that when a Nara calls a woman "troublesome" it is practically a marriage proposal. Hell, Itachi would even call it a proposition to his pure, innocent sister to start making babies in the middle arena. Yes, after the match, this boy will be given a good talking-to by Itachi. And Shisui. And Obito. And Fugaku. Perhaps it is time to appeal the Hokage Tower to have a temporarily lift Great-Uncle Madara's house arrest. Itachi has heard tell of the prolonged horror story that was Fugaku trying to court Great Uncle's favorite niece Mikoto. Yes, Madara will be good to bring along when Itachi gives the Nara boy his talking-to; with luck, Madara will make the Nara menace drop dead of fear before Itachi even opens his mouth.

Itachi's daydreams of bloody murder and vengeance are cut short by a shrieking Satsuki in the middle arena. She has pinned the shiftless, shadow-bending pest to the muddy ground and her eyes spin like whirlpools about to suck the hapless Nara down to hell.

"You're hard!" Satsuki growls—or attempts to growl; it is hard to look intimidating when you are ninety pounds and currently look like a disheveled kitten drowning its own sweat—"Does my anger arouse you? Does it, Nara? Does it?"

Overhearing this, Itachi immediately skips from planning a talking-to to considering if that idea of a coup Great-Uncle Madara wanted to throw had some merit. No, Itachi is getting ahead of himself; that would take more planning and dear Satsuki is too innocent and fragile to handle the hardships of a civil war. Also, they are still grounded from the last time Mikoto caught them planning world domination because of a slight to Satsuki's virtue.

"Poor Satsuki, too good for this sinful earth, too innocent," Itachi whispers to himself as he strokes the crow has for some reason landed on his shoulder, plotting even bloodier murder and vengeance.

In the background, Satsuki tries to throw her opponent through the opposite wall of the arena, and Nara Shikamaru realizes he will always regret this as the day he got so scared he popped a boner.