Disclaimer: If you know who they are, then they're not mine.
Notes: Gratuitous killing of OCs.
OoOoO
No one knows it, but the first time Kakashi killed someone, he threw up everything he had eaten that day. That's because they all assumed he was shocked over being the one to discover that his father had killed himself. Hatake Sakumo had lost his honor and most of his pride, but not nearly enough for him to resort to samurai methodology. No, Kakashi had killed him on Sandaime's orders, as the last person Sakumo would suspect. Sandaime had said Sakumo would snap, would turn on Kakashi, on the village, for their reaction to his actions. "He could cause the end of our village," he told the eight year old. "Now, do as your Hokage asks, for the good of Konoha."
Kakashi did, and a small part of him was glad that not even Kyouji, his mother's student and by proxy his babysitter on more than one occasion, suspected anything other than suicide. It affirmed that he was not just good at his job, he was one of best.
Uchiha Obito was a mark Kakashi had not intended to go after, and he told Sandaime as much when the man gave out the order. Sure, the taller boy was more than a bit of a crybaby and would only ever be a mediocre shinobi at best, but Obito was a teammate, someone he genuinely cared about. Yes, Kakashi had cared about his father, but the White Fang of Konoha was more often than not in the middle of a battle when he was alive, spending a minimal amount of time with the last reminder of his deceased wife.
At the last minute while saving Rin, Kakashi changed his mind. No matter what Obito had said or done to make him important to his jounin teammate, Konoha always came first in Kakashi's mind. Konoha was home, and Obito, as Sandaime had pointed out, was deadweight. There was more to Sandaime's reason for wanting Obito gone, apparently he had seen something he shouldn't have, but Kakashi was a tool of his village, and tools don't ask questions.
There were others over the next couple of years, more often than not shinobi who Kakashi didn't know personally. Minato, as he became Hokage shortly after Obito's death, gave him the assignments now, though Kakashi had a suspicion that the Professor still had some sway over who lived and who died. The order to execute Rin had been from him. It was understandable, Rin hadn't been stable since Obito died, and Kakashi actually preferred to be the one to do it than some faceless Hunter.
Kyouji was an uninspired target at best. Kakashi had seen this coming for years, even before he was ordered to kill Obito. Kyouji had a devotion to Minato that bordered on blind, and Kakashi had found out months after the fact that what Obito had seen was Kyouji and Minato in a very compromising position. Minato had chalked it up as a moment of weakness when he explained the incident to Sandaime after, which was why Kyouji had lasted longer than Obito. The Uchiha would have told, and that was something Sandaime couldn't afford. The Yellow Flash was all that was keeping Konoha alive at that point, and he could forgive Minato so long as it never happened again and the one witness disappeared.
Somehow, though, Kyouji had known Kakashi was coming, was even waiting with tea when Kakashi crept in. "I knew," he said very quietly. "That you were the one to kill your father. The tanto angle was all wrong. And if it's all the same to you-" In his shock and embarrassment at being caught not once, but twice now, he failed to notice the wires looping around him until it was too late "-I'd like to go out with my dignity intact."
Hours later, Arashi came in and, horrified at his cousin's actions, released Kakashi just as news came that Kyouji had been killed by the Yondaime Hokage trying to assassinate the man himself. Kakashi internally questioned the man's sense of dignity, but figured Kyouji would rather be killed by Minato than anyone else.
With Minato as Hokage, Konoha saw the longest stretch of peace in any Hidden Village's history. While it allowed for the population to be steady for more than a couple of months, the council and Sandaime knew it wasn't good for bringing money into the village or said village's continuing existence. Plans were made so that it would look like the Yondaime Hokage had been murdered by emissaries from Hidden Cloud, thus sparking the war Konoha needed.
The Kyuubi got to Minato first.
Whispers circulated Konoha of a shinobi from their own village with orders to weed out the weak and traitorous of their fold. "Careful," they'd caution, only half joking. "The Executioner will get you."
The Executioner. Sharingan Kakashi by day, a boogieman used to scare child-nin at night. Kakashi didn't care, he had a job to do, and was still damn good at it no matter what Kyoujji had said. Hiko of his ANBU team was the next target he got that he actually knew, and was one of the people Kakashi would've killed without orders. Hiko was scum, dragging the reputation of the ANBU down through the mud and filth. Kakashi killed him while on a mission with his team. It had looked like one of the enemy-nin had gotten him with a poisoned senbon, but Arashi had looked at the dying man and something changed in his stance and he'd never looked at Kakashi the same way again.
The fellow-nin assassinations stopped with the revelation of Orochimaru's treachery, and Kakashi was suddenly faced with someone he'd soon consider something of a friend. Tenzou was a bright boy, smart for his age, and the lone survivor of the Sannin's experiments. He had been adopted by Arashi and Aya, both members of the first ANBU team Kakashi had captained, and looked up to Kakashi like no one ever had. Kakashi refused to think there was anything more to it than that.
Arashi was Kakashi's choice to kill. The blonde had been planning on leaving, it was obvious in his eyes. Like with Rin, Kakashi preferred to be the one to execute Arashi instead of anyone else. Arashi had been his strongest supporter since Minato's death, and a damn good shinobi. Kakashi was almost sad to see him go, but Arashi had outlived his usefulness to the village. Aya lasted a year longer, but then Kakashi couldn't put off getting rid of her any longer. If he was forced to be completely honest, he hadn't wanted to leave Tenzou without some form of family. In the year after Arashi's death, Tenzou moved to the ANBU barracks and distance formed between the teen and his surrogate mother.
By the time Kakashi had passed and subsequently lost his gennin team, the legend of the Executioner had all but been lost as Copy-Nin Kakashi became too valuable to waste on a hunter-nin's job. Kakashi breathed a sigh as he executed his student turned traitor and moved to join the remainder of his team-
-only to feel the prick of a needle in his skin. Tenzou was standing there, holding one of Sakura's hypodermic needles, now empty. The effects, which Kakashi had never felt firsthand, only observed, were familiar as the ones he'd watched Hiko and so many others succumb to. "Why?" he managed as paralysis set in and breathing became that much more difficult. Off to the side, he could see Sakura and Naruto watching impassively, their friends confused but accepting of the situation.
Tenzou just looked at him and gave Kakashi the same reason Kakashi had given his other targets.
"For the good of Konoha."
