Five

A former time traveling assassin who is behind some of the most famous unsolved murders in history. Can teleport and time travel, managed to land himself into the literal apocalypse with no way back, with no real idea how he actually time traveled and actually managing it was a miracle. He spent. A lot of time there. Kind of went insane from the isolation, he became very attached to a Plushy he found. Her name is Delores. After a long time with a proper shelter in the wasteland and getting closer to getting the calculations done to travel back someone. Approached him about an opportunity. If he became one of their agents, one of the ones making sure the time line goes as it should by killing beings who would interfere regardless of of its their actual fault or not. If he would do that for awhile they would let him retire in whatever time period he chooses. He wouldn't be allowed close to the start of the apocalypse though, it was a fixed event that can't be changed, she said. He went along with it for awhile. Became their most effective assassin. He was the lab rat for an experiment, to make the perfect killer by injecting the Genes of some of the most famous killers in history. He never complained, never taking joy in killing his marks and continueing to plan how to get back to his family. On one of his missions he finally had a revelation. How to get back to the family, which was the only reason he survived that long. Fought that long. Persisted. It did work, but rather then being the old dragon he was before he was. A lot younger. As small as when he first time traveled. At least he manged to get directly to his family, a week before the end of the world. The commission, his former employees, did try to stop him from averting it but they failed. They did manage to make it a lot harder for him, but he persisted. He managed to keep his family well enough, except the one that got kidnapped while he was investigating a lead and thought everyone else could protect each other. He underestimated how much everyone has grown apart in the years he wasn't there. He did try afterwards to actually comfort him, Klaus, after finding out what he went through, but he was never able to mature emotionally so. It failed. He tried though. He befriended one of the top assassins sent after him, Hazel. Both just wanted a life away from the commision after all they had to do for the job so. They did manage to get along rather well. Finding out the cause of the apocalypse was his small sister though that was believed to not have any magic power, their dad just suppressed it, was an. Experience. They did manage to do something against it. After it actually happened, he manged to make himself and the rest of the family time travel and they had to stop another apocalypse. And Klaus might have started a cult and everyone else mange to just mess things up their own ways but in the end. At least everyone except the one who has died before this whole fiasco, Ben, was alive which is. Something. And better then expected after all the problems. Still, the commission still had a problem with them and they manged to actually get away from that and now. They're here. He adopted a small puppy as an emotional support animal, his name is Mister Pennycrumb.
Five is mentally really old. Physically barely older then a child. Emotionally is a whole other issue, with never really having the opportunity to actually grow up properly or learn how emotions and people actually work. And the commission only really taught what he needed for missions. He comes of as really cold, but he loves his family and the ones close to him dearly even if he's horrible at showing it. He will do whatever it takes to keep his family save.
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Five Hargreeves from The Umbrella Academy
IKTR:1