Y/N has a mastery of every weapon: be it melee or firearm, but his prefered weapons are his Vibranium cybernetic arms and a grenade launcher.
History:
With the disappearance of North-America's Hero Captain America and the leader of the Nazi criminal organization Hydra: Red Skull, Hydra knew there would be a time when their star-splanged enemy came back, and even with their most recent adquisition: Captain America's best friend James Buchanan 'Bucky' Barnes, they were at severe disadvantage and needed to prepare a better soldier to stop their enemy once and for all!, all they needed was a opportunity.
And one came around when they kidnapped an Afro-American child, a child that was born unnaturally strong. With their success at his kidnapping, they proceeded to supress his memories so they can condition him to their benefit: They also trained him in different martial arts and fighting styles, they experimented on him with a perfected Super Soldier serum, they also installed cybernetical fibers in his arms to turn them into stronger, robotic arms, they also fed him information so he could be strong and smart at the same time. When he was sent on missions, his ruthlessness and professional behaviour gave him the codename "Soldier of The End" because they knew he would be the end for Captain America if he indeed came back.
Their experiments, extreme training and conditioning produced some after-effecta on Y/N's body: his skin turned pitch-black and had orange glowing cracks across his body, his cybernetic arms turned black and grew spikes giving them a more menacing appearance and his eyes glowed the same shade of orange as his body cracks.
To keep their best soldier (weapon) always around, they put him sometimes in cryo-stasis to keep him fresh and living. Years passing as ages changed and Hydra still was around and with it, the Soldier of The End, the time came when their suspicions were proven true: Captain America was back!, so they prepared their Super Soldiers to start their plans of obtaining more power and destroying Captain America with any other Hero.
Now, with the desertion and disappearance of the Winter Soldier, Hydra defrosted and dispatched their trump card: the Soldier of The End. With it's constant attacks, the Avengers were very wary and careful of what they could do to defeat that unbeatable behemoth of a man, as him was gaining too much advantage over them and with him in Hydra's side it would be dangerous for the people if they didn't take care of him!
