Bucky Barnes

Sergeant James Buchanan "Bucky" Barnes was a former soldier of the 107th Infantry Regiment and the childhood best friend of Steve Rogers. Barnes was conscripted and assigned to the 107th in 1942. His regiment was captured by the forces of HYDRA, but Barnes along with what remained of his regiment were rescued by Rogers, who had become Captain America during Barnes' military absence. Joining forces in the continuing war, Barnes and Rogers formed the Howling Commandos to battle the Red Skull's forces and the Invaders to serve the people, stopping any crime.

During an attempt to capture HYDRA scientist Arnim Zola and stop a rocket heading towards Washington D.C, Steve and Bucky tried stopping the rocket where he fell off and vanished and was then presumed to be deceased.

The Man on The Wall
Bucky woke up in a Soviet facility and was given a new arm, Bucky didn’t remember the events of the rocket, so he became a Soviet Assassin as he was slowly brainwashed as he slowly became the most feared man and the Soviets gave him an anti-aging serum, so if that Bucky took an unhealthy lifestyle, his aging and skill would not be affected. Bucky, during his time as The Winter Soldier, he was training Natasha Romanoff (Black Widow), who was working for the Black Widow unit at the time and trained her. Eventually both fell in love, but kept their love secret, but was found out about and eventually Bucky was brainwashed enough to not feel love anymore, later on, she defected to the Americans.

Bucky was approached by current Russian Dictator at the time, Nikita Khrushchev, and was asked to meet him in an undisclosed location at the time. He was lead to the Siberian Bunker where Red Skull (A decoy at the time) and Baron Zemo met and eventually discussed the recruitment and Bucky was Enlisted as the assassin for HYDRA and The USSR (United Soviet Socialist Republic) and was labelled "The Winter Soldier" by the Russian Military.

The first assassination Bucky did was a British Chairman by the name of William McBradley, a former RAF and one of the many men who destroyed HYDRA's Base in Frankfurt, Germany. When the Chairman met a United States Defense Secretary, he was shot in the head by Bucky when he was scouting at the Great Wall of Berlin, where he had got the name, The Man on The Wall. His next one was in 1979, he was tasked of killing former "Bucky", Jack Monroe aka Nomad, Bucky executed this by confronting Jack at a Bar off the coast of Alaska and shooting him dead in his chest twice, killing him instantly. Bucky had many more assassinations that lead up to The Winter Soldier.

The Winter Soldier
When The Soviet Union fell, Bucky went into hiding as he slowly started to emerge taking out key figures in SHIELD and in HYDRA. One night Bucky shot the Decoy Red Skull dead in his office leaving behind a Red Star on his body. Steve Rogers (now with The Avengers) and SHIELD start to investigate the murders as they trace back to the British Ambassador to that. The following week, Bucky plants a bomb under Nick Fury's escort vehicle and as they make their way down to the U.S Capitol, It blows up with Bucky emerging and taking out the rest of The SHIELD soldiers as Steve deals with Bucky after the attack, but Bucky overcomes Steve as Bucky escapes.

Bucky plans to next takedown Black Widow and eventually kill Steve Rogers by the orders of Alexander Pierce (A Hidden HYDRA agent infiltrating SHIELD), Bucky declined his orders and wanted to go right in as he then targets Maria Hill, in a failed assassination attempt, she lives and recovers from the assassination attempt.

When Alexander Pierce launches the attack on the Helicarrier Fleet (Ship Five), this gives Bucky the opportunity to kill Steve by his orders and they do engage in battle, but at the price, Steve snaps Bucky out of the state he was in as they both along with Black Widow take down the invading HYDRA soldiers and kill Alexander Pierce in the process. SHIELD eventually gave Bucky the trust back and he was an ally before he went into hiding.

Civil War
Bucky Barnes retreated to an underground facility in Los Angeles, California where Steve Rogers and Sam Wilson go to meet him as Bucky recalls everything he's done wrong. Steve and Sam recruit him on their side as Steve tells Bucky of the Superhuman Registration Act and Bucky agrees.

They confront Tony at a facility with 30 on 30 battle and eventually follow him to a facility to confront Baron Zemo. Baron shows Tony the footage of Bucky killing his parents, fueling the rage inside Tony as they engage in a fight. While Bucky is punching Iron Man repeatedly, Iron Man blasts off Bucky's arm leaving him incapacitated and unconscious as Steve defeat Iron Man; taking Bucky to Wakanda to put him in Cryostatis where he took a nice nap.