Bucky was Captain America's partner during World War II. After being brainwashed by the Red Skull, he became an agent known as the Winter Soldier but later broke free and became a freelance mercenary.
World War II
In 1943, Bucky helped Captain America to get inside the Red Skull's fortress in Norway. After the two American allies defeated the HYDRA goons, Bucky and Captain America pursued the Red Skull in his rocket ship, but the Red Skull got away and set the rocket to blow in 30 seconds. As Bucky got his leg stuck to the ladder, Rogers tried to free him from the bars, but Bucky said the world needs Captain America more than Bucky, and so he knocked him off the rocket and into the frozen water to save him before he died in the explosion in tragedy whilst saluting farewell.
Change of reality
Bucky crashes into the ocean after Captain America alters reality When Captain America and Baron Strucker touched the Cosmic Cube in the 21st century, Captain America (unknowingly) changed reality to make it so Bucky survived the explosion. Bucky ended up frozen somewhere in the Arctic ocean.
Change into the Winter Soldier
He lost an arm in the explosion and was later found by the Red Skull and HYDRA. He was brainwashed and given a robotic arm. The Skull trained him and sent him on many missions. One such mission was to infiltrate Nick Fury's group when they blew up a HYDRA base. He took out the team except for Fury, and got out of there before the explosion that took Fury's left eye. Between missions, they put him into hibernation so he wouldn't age and left his honed combat skills intact.
Creation of the Red Hulk
He snuck onto the S.H.I.E.L.D. Helicarrier, and stole the sample of the Hulk's blood. Then he injected it into the willing Thunderbolt Ross, who changed into the Red Hulk. Later, he went to Washington, D.C. where he met up with Secretary of Defense Dell Rusk, along with Falcon, Doc Samson, and the Red Hulk.
When a virus affected people outside of Avengers Mansion, Winter Soldier, along with Doc Samson and Falcon, attacked the Avengers. Doc Samson and Falcon were defeated, but Winter Soldier managed to capture Captain America and take him to Dell Rusk, who was revealed to have been the Red Skull. Bucky cured Captain America of the virus and later fled.
Cap defeated the Skull and took him into custody.
Reunion with Cap
After Bucky came out of his mind control, he found out about the Sleepers and started to locate and destroy them to take revenge on what skull had done to him. Steve had suspicions on who Winter Soldier was and asked Nick to help him out, but he had a dislike against it because of what he did to his team while he was still under the Red Skull's control.
After Red Skull broke out of prison and Cap and Nick encountered a Sleeper that they helped Bucky destroy, Steve called Bucky by his name. He ended up attacking Fury while Cap tried to continuously talk to him, to which Bucky showed his anger at him when he thought he'd left him behind. He then told of what Red Skull had done to him and helped to fight him in his Mega-Sleeper. After it was destroyed, Steve asked him to come back and set his past right with the Avengers, but Bucky stated he had to clear up the wreckage of his past alone and disappeared after he blew up the wreckage of the Mega Sleeper. He then told Steve "Tenfold, Cap. Bucky out."
During the Galactus invasion, the Winter Soldier was brought in as a weapon specialist and fought with the team to battle the Fire element of Galactus' Heralds (Firelord).
He and the other heroes left for the Avengers to be praised as Earth's Mightiest Heroes by the people.
He is a true believer in Captain America and is quite a patriot. He usually makes jokes on opponents like the time he made a joke about Baron Strucker about his "hair issue" being bald and all, which angers Strucker.
As Winter Soldier, he is somehow cold and emotionless person as he took orders from Dell Rusk without hesitation or question. After breaking control, he restored his friendship with Cap but retained his impulsive side.
Bionic Arm: Due to his missing organic arm, HYDRA has replaced it with an artificial one, which grants him multiple abilities.
- Super Strength:
- Enhanced Reaction Time: For objects or things which move too fast for Bucky to keep up with ( mostly things that can move many times faster than the speed of sound ), his bionic arm can compensate for this due to its auto reflexes ability. This means that his arm has greater reaction time than any human who has eve lift and will ever lift.
- Super Durability: It is bulletproof, fireproof, shock resistance, knife proof, etc.
- Stabilization Sensors: Bucky can detect the balance of objects (namely Captain America's shield) and throw items with pinpoint accuracy. He was able to throw Captain America's shield with perfect accuracy and cause it to return when he used his bionic arm.
- Sensory Array: The arm houses different sensors which allow him to pass through security such as metal detectors without setting them off. It can also shield other metallic objects from detection such as firearms and knives.
- Extended Reach: He can apparently either control his bionic arm even if it has been removed from his body (possibly by cybernetic implants), or his arm can be programmed to perform certain actions on its own while removed from his body.
- Electrical Discharge: He can discharge bolts of electrical energy from his arm's palm.
- EMP: He can discharge an EMP rendering electronic devices useless. He failed to use it on a prepared Iron Man.
- Holographic Disguise: The arm can create holograms to appear, look and feel like a normal human arm.
- Hacking: The arm can hack advanced computers, such as that of S.H.I.E.L.D or Stark's.
Naturally Enhanced Physiology: Bucky is a gifted Olympic-class athlete and expectional acrobat. Even before being turned into the Winter Soldier, as Cap's sidekick, Bucky has already performed incredible physical feats when it comes to strength, speed, and durability. His physicals is even enough for him to regularly contends with superhuman beings and highly trained peak humans. After his transformation into the Winter Soldier, Bucky received more rigorous training from HYDRA, combine with various types of steroids, biofeedback treatments and a strict diet, he becomes powerful enough to contend with highly skilled enhanced humans like Captain America himself.
- Peak Strength: Bucky possesses peak human level of strength, enough for him to overhead 454 kg with exceptional effort. With this strength, he is strong enough to lift a full grown man with one arm, lift a motorcycle with maximum effort, toss heavy objects dozens of feet away and hurt beings with superhuman durability even without the use of his metal arm, he is also strong enough to punch through hard materials cut as concrete, wood and dent steel.
- Peak Speed: He is exceptionally fast, being able to keep up with Captain America in close quarter combat, defeat Nick Fury in around 10 seconds or so, and catch up with modern motorcycle on bare foot.
- Peak Reflexes: He can react at great speed, this was proven when he dodged attacks from a low level superhuman (Captain America) and destroy Stark's and HYDRA weapons before it get to him. Even Captain America was surprised at how fast he was moving.
- Peak Agility: He is exceptionally agile, far more than an Olympic level athlete, and he can combine this agility with his fighting style to create a more acrobatic way of fighting, which makes it very hard to hit him, even if the opponent is a superhuman.
- Peak Durability: Bucky possesses incredible durability, surviving a massive explosion point blank (though at the cost of his left arm), the same explosion knocked out Captain America with just its shockwave. He is also durable enough to be uninjured when falling from hundreds of feet, tank punches from Captain America and only received endurable discomfort when having all of the electricity in Red Skull's giant robot ran through him.
- Peak Stamina: He can exert himself at his peak for a hour or two before finally run out of breath.
- Peak Endurance: With HYDRA's rigorous training, he has gained enough willpower to endure pain, hunger, thirst, far for longer than a normal human can
- Accelerated Healing Rate: He can recover from injuries at a very fast rate. His immune system is also stronger than normal humans, and he ages a lot slower than an ordinary man
- High-Level Intelligence: He is very intelligent, often being tasked with dangerous missions that most normal soldiers can't handle.
Master Martial Artist: Barnes is a dangerously skilled martial artist and hand-to-hand combatant. He received training from World War Two hand-to-hand combat luminaries William Essart Fairbairn and Colonel Rex Applegate as well as Captain America (Steve Rogers) in multiple martial arts, and acrobatics as a teenager during WWII and was trained in more of them while being molded into an assassin by the Soviet Union. He has single-handedly beaten Captain America, a squad of S.H.I.E.L.D. agents, Nick Fury, defeated a giant HYDRA robot by himself.
- Master Shieldmanship: Barnes became rapidly proficient with his former partner's shield. He is able to throw it with near perfect aim striking multiple targets in a single throw and achieving a boomerang-like return after throwing it at single person or object.
Master Marksman: He is an extremely accurate marksman. Skilled in sharpshooting and knife throwing.
Master Acrobat: He is an Olympic level athlete and acrobat capable of many difficult acrobatic feats.
Advanced Scout: Barnes is a very gifted scout and adept at stealth and concealment.
Multilingual: He is fluent in English, Russian, German, Japanese, and a little French. He might be able to speak other languages.
Master Spy: He is an expert in the field of espionage thanks largely to World War Two hand-to-hand combat luminaries William Essart Fairbairn and Colonel Rex Applegate, his former partner, Steve Rogers, the United States military, British SAS regiment, and the Russian Government. He is skilled in stealth, demolitions, survival, deducing other persons ways of thinking and other fields.
Master Assassin: Barnes is an adept of his generation as Matthew Murdock and Elektra Natchios is of theirs, possibly the most lethal assassin in the Marvel Universe rivaling others such as Bullseye or Elektra. During an operation on the Russian Front with the Invaders, Barnes has from concealment thrown a 60 centimeters-long knife to penetrate the winter uniform outer garment of a German soldier with such accuracy as to pierce his heart in high arctic winds several meters. Barnes has mastered and implemented several methods to silently eliminate sentries with bladed weapons, garrotes or his bare hands, making him as lethal in his own way as his former Invader teammates, the Torches, Union Jack or Namor. He is a master at stealth and tracking and is very intelligent. He was able to render Wolverine's superhumanly acute senses such as smell completely useless by luring him to an abandoned warehouse that was completely soaked on the inside with oil and even soaking himself to make it so that Wolverine could not detect him. Barnes has made a habit out of constantly studying his surroundings and depicting what he can and cannot do in whatever situation he should fall in much like his former partner, Captain America before his death. During Barnes' visit to the Captain America exhibit that had been made to honor him after his death, he was constantly detecting potential ways to sneak in and out of the museum and the room without being detected and only taking out a small number of security to do so. The Black Widow stated to Tony Stark that he was one of the most dangerous men she knew.
Bionic Arm: Bucky possesses a bionic as replacement for his missing left arm.
Winter Soldier Uniform: Impact resistant, bulletproof and security jammers are built into it.
Modified Handgun: The gun is capable of penetrating even fabric of the thickness and composition of AIM uniforms, a combat knife, sniper rifles, various other automatic weapons and various other mission-special equipment.