Disclaimer: The characters, items, places etc of Naruto are property of Masashi Kishimoto. These objects are used without permission for entertainment only, not for making money. No infringement is intended.
Edging on ItaShi I suppose, but ignorable if you wish.
By Nanaki Lioness
Peace has no price-tag attached to it and Itachi will give everything he can to preserve it until he has nothing left, since no-one else will do so and he is all too aware of this even at his age. When he is given the order to kill Shisui he recoils, he protests, he cries, he bargains and finally he accepts. This is what leads them to the Nakano River on a cool day as they enter summer- an invite from one best friend to another, which is readily accepted because friends trust the other not to attempt murder, which is precisely Itachi's intention.
Shisui is anything but calm as he struggles beneath Itachi's hands, lips moving as he tries to speak. His words are muffled by the water and incomprehensible, but all Itachi can think is 'stop breathing, stop breathing, stop breathing' in more ways than one. He wants him to stop breathing in the literal sense, else he wouldn't be drowning him, but he also wants him to conserve as much air as possible in his lungs rather than filling them with water so Itachi can change his mind if he needs to. Not that he can because this is his duty, but it's always nice to dream.
Dreams, he decides in that moment as he watches Shisui flail and suck in mouthfuls of salty river, are for children and civilians. Shinobi can't afford to have dreams because they get wrenched from them like children are wrenched from their mothers and placed on the battlefield, barely able to walk but forced to hold a kunai and try not to hurt themselves with it. The intrinsic desires of a child to play often leads to them doing just that, turning the weapon over in their hands like one would inspect a favourite new toy.
Itachi's own lips are moving, whispering a mantra that is the only thing keeping him sane- "forgive me, forgive me, forgive me," he repeats over and over, until he is speaking only to himself and he holds a dead body in his hands. He is only thirteen so he is unsurprised by the burning in his eyes and the trails on his cheeks and he pulls Shisui to land, water wrenching itself from his cousin's throat as Itachi tilts his head to one side.
Itachi knows basic first aid and recovery techniques, but all he can remember at that time is resuscitation is done via mouth to mouth and pumps of the chest, so he folds his hands over Shisui's swollen chest and pumps a few times. Water spits itself up from his blue lips before Itachi captures them with his own, closing his eyes and telling himself that they are sharing their first kiss. Shisui tastes of salt and bitter death, and Itachi thinks that his own lips probably taste of failure.
"Stop tonguing his corpse," a voice from his side says, and Itachi reluctantly pulls himself up from Shisui to meet Madara's eyes. There's blood on Shisui's face as he does so, leaving Itachi to wonder if that's why his eyes are on fire after all. He puts a hand to his cheek and cleans away sticky crimson, rubbing his fingertips together lightly in mild shock.
"It's the Mangekyou," Madara continues. "It's awakened thanks to Shisui's sacrifice. You should be proud of yourself."
Itachi can't imagine ever being proud of taking another's life, especially someone like Shisui, but he is still a child. He is aware of this when all he wants is to go home to his mother and curl up with her like he did when he was a small boy, allowing her to stroke his hair in comfort while he cared for nothing but her touch. He tells himself to stop thinking such delusional thoughts, because soon his mother will be as dead as Shisui and then he will have no-one but Madara.
"It hurts," he rasps to this man, because he is the only one who will be his comfort in the future. Madara simply stares at him without a flicker of emotion, finally shrugging the comment off as he turns to walk away.
"Leave the body," he states. "Clean your blood from it first, then come with me."
Itachi stares down at the pale skin of his cousin and does what is expected of him, just like he always has done. He meticulously wipes the blood free from his skin and kneels at his side for a moment before reaching over to shut his eyes. Then he stands and follows Madara into the clearing, leaving behind the shattered remains of his old life so he can head towards his new future. It is his duty, he reminds himself. He must prevent war at all costs, so if that means giving up his life, his soul, his love, his family then so be it. He tells himself he is prepared, but really he knows he isn't- however he can give the illusion of being so and that is enough, for now.