I'm no longer the Winter Soldier. I'm James Bucky Barnes.
Background
Personality
Bucky is loyal, brave, honest to a fault, headstrong, resilient, and has a strong sense of justice and honor; during the 1940s he was charming and a ladies man, in present times he tends to be more distant and self-contained.
As the Winter Soldier, Bucky was an elusive, dangerous, and amnesiac assassin. He was ruthless, brutal, and under the complete control of HYDRA. After Steve Rogers reminded him of his past, Bucky broke from his programming and saved his friend and former target from drowning.
Powers and Abilities
He's fast... strong... had a metal arm
Powers
Super Soldier Serum/Bionic Arm: Bucky's bionic arm gives him enhanced strength superior to that of A normal human's. However, the bionic arm is not the only source of his physical attributes; he was given some form of the Super Soldier Serum, which affected his tissue strength and physical capabilities to the very peak of human potential.
Enhanced Strength
Enhanced Durability
Enhanced Speed
Enhanced Stamina
Enhanced Reflexes
Enhanced Agility
Accelerated Healing
Slowed Aging Process
Bionic Arm
Superhuman Strength
Superhuman Durability
Abilities
Master Hand-To-Hand Combatant/Martial Artist
Master Marksman
Expert Pilot
...
Name figuring upon "The Wall of Valor" memorial wall at the SHIELD Science and Technology Academy.
Most of the intelligence community doesn't believe he exists. The ones that do call him the Winter Soldier. He's a ghost, you'll never find him..
Steve Rogers’ best friend Bucky Barnes was a member of the Howling Commandos and a former member of the 107th Infantry Unit. He had been captured during the Italy campaign by Red Skull's HYDRA forces and experimented on by the Swiss HYDRA scientist Arnim Zola, with Rogers, re-branded as Captain America due to Project Rebirth, rescuing him from the facility. He joined the Howling Commandos in gratitude, specifying he was joining for Rogers, not for Captain America. On one mission to capture Zola, however, Barnes was thought to have died from falling down a crevice while pinned by HYDRA soldiers. However, thanks to the experimentation done unto him earlier, he survived and was recovered by Zola (who had presumably just been released by the SSR in exchange for information about HYDRA) and some Soviet agents, with his arm forcibly removed through surgical operation and replaced with a bionic arm, and presumably undergoing brainwashing to remove any memories of his former identity. However, he resurfaces decades later as the Winter Soldier, a brainwashed, mega-enhanced Super-Soldier doing dirty work for a mysterious organization. By the time of the end of the Cold War, he was kept so classified that most of the intelligence community had doubts that he even existed, and gained the codename "The Winter Soldier," acting as an assassin for the USSR and presumably HYDRA. He once had an encounter with then-KGB agent Nastasha Romanoff while she was protecting a nuclear engineer, where he managed to shoot out their protection vehicle's tires and also kill the engineer by shooting straight through her gut. His MO was using Soviet rounds that were from antiquated weapons and thus "untraceable." By the time of the 21st century, the hardened Winter Soldier has no memories of his former identity and that suits him just fine — he is simply a killing machine. The Winter Soldier is first seen in the film leading a herd of fake police to chase after Nick Fury. Eventually, the Winter Soldier shoots a bomb with a magnet that attaches itself to Fury's vehicle, which explodes and flips the car over. The Winter Soldier walks over to Fury, but he finds a hole in the ground where Fury should have been. Fury then limps over to Steve Rogers' apartment to attempt to tell him that SHIELD has been compromised.
However, the Winter Soldier manages to find where Fury is hiding and shoots Fury through the wall, three times, seemingly killing him. Steve chases after the Winter Soldier and attempts to throw his shield at him, but is shocked when the Winter Soldier catches it, and throws the shield back at Steve before disappearing.
Later, Natasha reveals to Steve that the Winter Soldier has been responsible for many assassinations for 50 years. After Steve and Natasha escaped Hydra once again, Rumlow requested the Winter Soldier's help. ("Call in the asset")
Alexander Pierce, the official head of the reorganized HYDRA terrorist group operating within SHIELD, finds the Winter Soldier in his apartment, and tells him to assassinate Captain America and Black Widow, wanting their confirmed deaths in ten hours. However, Pierce's house-keeper stumbles upon their meeting and sees the Winter Soldier, resulting in Pierce shooting her with the Winter Soldier staring unfazed.
After realizing that Alexander Pierce is a follower for HYDRA and is intending to use Fury's insight project to kill anyone who could potentially oppose Hydra, Steve, Natasha, and Sam Wilson attempt to drive to the Triskelton, but are confronted by the Winter Soldier and his men. The Winter Soldier successfully manages to kill Jasper Sitwell by throwing him into the path of a truck. The heroes are split up, and the Winter Soldier sends his men to kill Steve Rogers while he goes after Natasha. A battle ensues, with Steve and Sam fighting the other assasins while the Winter Soldier fights Natasha. Eventually, the Winter Soldier is about to shoot Natasha, only to be charged at by Steve. The Winter Soldier quickly stops him by punching his shield. Steve fights the Winter Soldier, but the latter is able to match him move for move. Steve eventually removes the Winter Solder's mask, and much to his horror, Steve recognizes the Winter Soldier as Bucky Barnes, his friend from the past and whom he thought to have died. Steve says Bucky's name, but the Winter Soldier responds, "Who the hell is Bucky?", before disappearing.
The Winter Soldier returns to HYDRA's lair to get his mechanical arm fixed up after being damaged during the battle. While his arm is being fixed, he has brief flashbacks to his old life, from the fall he took to the moment he was recovered by Zola and the HYDRA agents, his left arm being amputated and replaced with the metal arm, and finally being placed in suspended-animation. The Winter Soldier cracks and attacks the person fixing his arm, sending him flying across the room, causing the other people in the room to point their guns at him. Alexander Pierce is called and comes. As he walks in he tells everyone to lower their guns, and asks the Winter Soldier for a mission report. Bucky however, merely stares out into space his mind on other things. Pierce, annoyed slaps him, which prompts the Winter Soldier to ask who Steve was. Pierce tells him that he met Steve earlier this week on another mission. Bucky then remembers the moment before he fell off the train during WWII, how Steve had reached for his hand. Bucky then claims to have known Steve. Pierce tries to appease him by praising the Winter Soldier's work and asking him to come back to do it again. Bucky, however, insists that he knew Steve. Pierce tells the scientists to prep the Winter Soldier to continue his mission, however one of the scientists comment that he's been too long out of cryophase. So Pierce orders the agents erased Bucky's memory again to start over and reset the Winter Soldier to his original killing machine mindset. Pierce walks out of the room with Bucky wailing in pain from being brainwashed.
Later, Steve, Falcon, Natasha, Maria Hill, and Fury, who survived his injuries, attempt to stop Alexander Pierce's plot. While Steve and Falconput overriding chips into two of the Helicarriers, the Winter Soldier is seen attacking the only people that were going to support Captain America. He then hijacks a Quinjet and heads on up.
When Cap and Falcon arrive on the third Helicarrier, the Winter Soldier suddenly appears out of nowhere and bowls over Captain America, seemingly making him fall off the Helicarrier. Winter Soldier then attacks Falcon to keep him from rescuing Steve, by ripping off one of his wings and throwing him off of the helicarrier. Winter Soldier had gotten close enough to the edge to notice that Captain America indeed had not fallen off the Helicarrier, and proceeds to head to the control panel to confront Steve. Steve attempts to talk with the Winter Soldier, telling him that a lot of people are going to die. After receiving a blank stare from his friend, Steve pleads with Bucky to not make them fight each other. However, the Winter Soldier doesn't move, leaving Steve with no choice but to attack the Winter Soldier with his shield.
A brutal fight breaks out between the two, with the Cap multitasking and attempting to put in the third and last chip. During the fight, the Winter Soldier gets a hold of the chip. Steve puts the Winter Soldier in an arm lock demanding he let go of the chip. Bucky however holds on to it, prompting Steve to dislocate his elbow. Steve then holds Bucky in a Rear-Naked-Choke. Winter Soldier then passes out and releases the chip. Steve rushes to place the chip into the Helicarrier's system, but the Winter Soldier recovers and shoots at him, hitting him twice. However, Steve still succeeds in placing the chip. Hill tells Cap to get out, but Steve tells her to shoot down the Helicarriers, making them open fire upon each other.
As the third Helicarrier begins to crumble, Steve heard a cry of pain and saw that the Winter Soldier was pinned down by a rail. The wounded Steve then lifts the rail enough for the Winter Soldier to crawl out. As soon as the Winter Soldier was free, he responds by mercilessly attacking Steve again. Steve again attempts to revive Bucky's memories, telling him his name, and that they were childhood friends, but the Winter Soldier rebuffs everything and yells at him to shut up. Cap, refusing to fight his friend, tells him so and drops his shield into the river below. Winter Soldier simply responds by tackling Steve saying he is nothing but a mission. Bucky repetedly kept pounding at Steve with his metal arm. When he paused for a breath Steve tells him to finish it, because no matter what, Steve will be "with him until the end of the line" (something that Bucky had told him years ago). Hearing those words, the Winter Soldier looks at Steve and hesitates. The Helicarrier crashes, throwing Steve out and sending him into the water below. The Winter Soldier instinctively grabs onto one of the metal supports and watches his friend falling for a moment. Bucky then lets go and falls after his friend. He pulls Steve out of water and to the shore. He makes sure Steve is breathing before limping away, without a word.
A couple weeks later, Bucky, is shown to be visiting the Smithsonian. He visits the Captain America exhibit, where he reads a display of himself. Bucky stares at it, desperate to remember the old life Steve spoke of.
Freed from HYDRA's control, Bucky went on the run from the government. After a bombing at the Vienna International Centre in Austria, it was believed the Bucky was the culprit and the murder of Black Panther's father T'Chaka. Bucky decides to go back under the ice so that Black Panther and his sister Shuri can fix the brainwashing from Bucky's brain.
Two years after civil war, Bucky is reunited with Steve in Wakanda after the HYDRA brainwashing is removed. Bucky later assists, Black Panther, Captain America, Black Widow and others at the battle of Wakanda, but Bucky is one of the 50% of the universe to disintegrate from Thanos' snap.
Bucky is resurrected after Professor Hulk's snap and helps the Avengers defeat Thanos and his army once and for all. He later attends Tony Stark's funereal after he sacrifices himself to defeat Thanos. Bucky is amoungst those who see Captain America return the Infinity Stones and says one final goodbye to Steve, knowing he will spend his time back in the 40's to live his life with Peggy Carter. Bucky watches from afar as an elderly Steve Rogers gives Sam Wilson his shield.
SPOILERS
In the first episode, Bucky is struggling with memories as the Winter Soldier, so he is having therapy to help get those memories out of his mind. It is also revealed that he has been trying to make amends with those who he caused trauma or helped to rise to power during his time as the Winter Solider. He states to a woman that is still abusing of the power he helped her obtain that he is no longer the assassin everyone knew him as before, but now just James "Bucky" Barnes, the best friend to Steve Rogers, and that taking her from her position of power is part of his effort to make amends.
Bucky now spends time with a elderly man called Yori who had lost his son years ago, as he was murdered while traveling abroad. The man sets Bucky on a date with a woman, but Bucky struggles with feelings of guilt as it is reaveled that he is the one who killed Yori's son when he was still the Winter Soldier. Because of this, he leaves the date when the woman starts to mention Yori's son, despite her complimenting him for being nice to Yori.