As Sasuke swept through the treetops, towards the Uchiha compound where a weak, naive Madara no doubt would be, he began to think.
Contrary to popular belief, you didn't feel overwhelming guilt after you made a kill. By now, Sasuke had snuffed out many lives, and while he did feel a bit guilty, one fact/thought barricaded him from crushing guilt: that, while there may be an alternate way, killing was sometimes the easiest, most convenient way. And it's not like the people he killed were bloodless either.
How old would Madara be? Presumably his age, perhaps a little younger, and definitely without the Mangekyou. It was probably stupid of him to want to venture into enemy territory (let's forget the fact that these people were his ancestors). Obviously, there was a high risk, but the fact remained that people from the future were just a lot stronger than people right now.
It's because, unlike the ninja here, new techniques had been invented and taught to him. In the future, there was a more in-depth understanding of chakra and jutsu. Now, they barely had healing jutsu and he doubted if germ theory was even a thing. He figured that since he had access to a wider repertoire of jutsu, he'd be a lot stronger.
Which is why all Sasuke needed to do was put up a little genjutsu and trot into Uchiha territory. Which is what he did, wandering the corridors aimlessly, hoping to stumble across Madara's room. He almost expected it to have 'Keep Out' scrawled on the door in bubble writing like a regular angsty teenager.
It was located in the centre of the compound, considering that Madara was the son of the clan head at the time. Just as expected, his room had an organised, yet chaotic atmosphere. Madara had decorated it with a personality, with clothes and weapons and riffraffs strewn across the floor. Sasuke presumed Madara was out training, but judging by the schedule near his bed on the wall, he'd be back in an hour.
Sasuke nabbed Romeo and Juliet from Madara's shelf and tossed himself onto the bed, helping himself to the cookie jar on Madara's nightstand. He sniffed it, determined no poison, and shoved the whole thing into his mouth. It didn't matter, because Madara was gonna die soon anyway. And it's not like fingerprints were a thing.
It was almost funny how the Senju and Uchiha were fighting like this, and yet, the first book on Madara's shelf, evidently read numerous times, was a play about two feuding families keeping two star-crossed lovers from being together. Especially if you considered Hashirama. Haha.
The door creaked open. Just as Madara walked in tensely, Sasuke flipped to the next page, bookmarked it and set it back on the shelf.
"Hello," he greeted, still poised gracefully on Madara's bed, munching on a cookie. Madara was tense and wonderfully frightened, albeit he hid it well.
Madara backed himself into the door, rummaging through his pockets for a weapon. He came up with a single kunai. It was large, sharp and no doubt heavy and hard to throw, because nobody understood simple aerodynamics right now. Sasuke moved his gaze from the kunai to Madara, taking the opportunity to examine his teenaged great-great-great grandfather.
His hair was shorter, about shoulder length and significantly less messy. His expression was youthful and panicked. At this point, considering Madara's current age, Sasuke should've felt the slightest twinge of guilt. If Madara was a baby, he probably would've. But this Madara was still a licenced killer, just waiting to turn into one of the biggest villains in all of history.
"You're the man from the battle. The weak, chakraless one," Madara muttered. Sasuke caught onto what he was trying to do: stall. He let him. After all, Madara still didn't realise that his own dumbass self was the one who soundproofed the room, and that Sasuke merely performed a jutsu that included miniature snakes entwining into the door lock. Teenagers - you could always rely on them to want that much privacy (but Sasuke took the cake for the most private teenager, considering his family was too dead to annoy him).
"Chakraless is a temporary state. You caught me at a bad time," Sasuke shoved his hands into his pockets. Despite this, he didn't seem any less threatening. Honestly, he didn't need a weapon to take this weakling on. Madara's strength was apparently 90% reliance on the Sharingan.
"Why are you here then? Are you a trick of the Senju?" Madara glared at him, but it lacked the danger Sasuke was used to seeing. He smirked. This was an opportunity to shake him a little.
"I'm here to kill you," he simply stated, "No, I'm not a trick of the Senju. Funny you'd say that. Aren't you best friends with one?"
Madara flushed crimson. Sasuke felt like he could've laughed his arse off, if only he wasn't about to kill someone.
"How do you know that?" He questioned vehemently. Sasuke paused. Should he answer or not? Well, Madara was dying anyway.
Sasuke leant forward, teasingly putting his index finger to his lips in a shushing motion.
"I'm from the future." He chuckled, no doubt seeming batshit crazy. Madara gulped. He wouldn't have believed when a strange man said he was from the future, but these circumstances seemed to be rather believable.
"Why are you trying to kill me?" At this point, Madara was trying to buy himself an extra ten seconds to live. Sasuke decided to humour him, shrugging.
"Let's just say you're not a saint in the future," he muttered, just as Madara pushed at the door handle, his attempt to escape failing when nothing happened.
Sasuke deadpanned.
"Do you seriously think I'm that stupid?" Madara went silent, glaring at Sasuke. And then he blew up into smoke.
Shit. Sasuke didn't think Madara would know such a high-level attack by now. The door fluttered, the scent of smoke still pervading the air. Sasuke flung into action, hunting Madara down. This was bad. He underestimated Madara and let his guard slip for a moment. Now the whole clan knew there was someone here, but this posed a good thing.
His mind whirred, figuring out how he could use this sudden occurence to his advantage. Before, he would've been silent and surreptitious, killing Madara using the least chakra so as to not alert anyone. Now, he didn't have to be capped, having granted himself access to his full arsenal of techniques.
Madara was quick like a rabbit, rushing outside to an expanse of green land. Sasuke deftly hopped from the compound's rooftop to the grass, quickly followed by numerous Uchiha, surrounding him in a circular formation. As he stared Madara down, his mind screamed at him, in neon, capital letters 'loose end'. He didn't care if he had to fight the fucking world. Madara was dying tonight.
The surrounding Uchiha conversed, but he didn't pay much attention to it, having been forced to dodge several incoming wakizashi and katana and chokuto while he thought up a safe, surefire way to kill Madara but not the clan, considering that his clan would literally die out. This wasn't the whole clan, but there were still several Uchiha to handle.
Wait. Sasuke did a mental pause.
"Hey!" He yelled at Madara, who glared at him menacingly. "Did you get anyone pregnant?!" Please say yes, please say yes.
Madara did not answer, but it was alright, because his body language told him that it was a yes anyway. He breathed a sigh of relief. Evidently, the surrounding Uchiha as well as Madara were perplexed at the question, but it only seemed to piss them off more. That, and the fact that Sasuke was virtually unkillable.
Sasuke never thought he'd be this glad for the dumb reproduction procedures of this time. The clan head, and the clan head's children would all have to pop out babies as quickly as possible, hence why sons were valued. Now, he could kill Madara without any qualms. It would suck if he killed Madara and thereby prevented his dad's birth.
A chokuto nicked him in the shoulder. It healed, but Sasuke had to take a moment to process the face of the wielder; he sort of looked like him, except Sasuke liked to think he was better-looking. The Mangekyo, along with Madara's, told him this must be Izuna Uchiha. Sasuke grabbed the blade of the chokuto with his bare hand, yanking the blade towards himself. He figured he'd use a weapon.
The second he acquired a weapon was the second the Uchiha decided to get more serious: bringing jutsu into the equation. Several deathly techniques came at him, and it would've been impossible to evade even one without dying. Sasuke figured it was time to pull one of his many aces out anyway.
Purple chakra solidified, forming the legendary Susanoo. The tension and fear was almost palpable. Sasuke had played his cards right - creating this beautiful moment of shock that would allow a clean shot at Madara's heart.
"You have the Mangekyou...no, the Eternal Mangekyou Sharingan. How?" Madara muttered, wiping the blood on his face with the back of his hand. Sasuke dug his hand into Madara's chest. Yanking his hand out, he had Madara's no-longer-beating heart in his palm. He let it plop to the ground with a sickening squelch. Madara's body soon followed.
"That would indirectly be your fault," Sasuke whispered. He wiped his bloody hands on his jeans.