Bucky Barnes

"This isn't a backyard, Steve, it's a war!"

- Bucky Barnes James Buchanan "Bucky" Barnes is the protégé and childhood friend of Captain America, and a member of an elite special unit of Allied soldiers formed in World War II known as the Howling Commandos. He was assumed dead after falling off of Zola's Train but somehow survived to return as The Winter Soldier.

The Avengers
Bucky Barnes' files is among the ones studied by Steve Rogers, awakened at the present days. Oddly enough, he's reported as "Missing in action", implying that S.H.I.E.L.D. thinks he may still be alive.

Captain America: The Winter Soldier
To be added

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 when Bucky said the world needs Captain America more than Bucky, he knocked him off the rocket and into the frozen water to save him before he died in the explosion in tragedy.

Change of reality
When Captain America and Baron Strucker touched the Cosmic Cube in the 21st century, Captain America changed reality to make it so Bucky survived the explosion.

Bucky ended up frozen somewhere in the Arctic ocean.

Change into the Winter Soldier
"Captain America has abandoned you, little one. You have a new teacher now."

- Red Skull to Bucky

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.

Creation of the Red Hulk
He sneaks onto the S.H.I.E.L.D. Helicarrier, and steals the sample of the Hulk's blood. Then he injects it into the willing Thunderbolt Ross, who changes into the Red Hulk. Later, he went to Washington, D.C. where he meets up with Secretary of Defense Dell Rusk, along with Falcon, Doc Samson, and the Red Hulk.

Code Red
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.

Character traits
Bucky Barnes is a loyal and brave man, a honest person and a good soldier. He firmly believes in the duty of protecting his Country, and is eager to test his own value. He's a very close friend of Steve Rogers, who he has always protected from bullies.

Barnes is a highly trained soldier, an expert fighter and a talented marksman. In battle, he uses canonical firearms.

Behind the scenes

 * Sebastian Stan was considered for the role of Captain America, but got the role of Bucky instead.
 * Bucky's uniform is based on his original and his codename The Winter Soilder.
 * About the role, Stan stated, "Steve Rogers and Bucky are both orphans and kind of like brothers. They kind of grow up together and look after each other. It's a very human, relatable thing.... I also wanted to look out for how their relationship changes once Steve Rogers becomes Captain America. There's always a competition and they're always one-upping each other. I paid attention to how Bucky is affected by Steve's change and suddenly Steve is this leader".
 * When Steve finds Bucky hooked up to machines in Arnim Zola's HYDRA Lab and Bucky is in a sort of trance, many fans assume Zola was experimenting on Bucky and brainwashing him with dormant Winter Soldier programming, thus possibly allowing him to survive the fall and appear in a a sequel (as Stan is contracted for more Marvel films).

Trivia

 * In the comics, Bucky is younger than Steve Rogers. In the initial stories by Joe Simon and Jack Kirby, Bucky was a teenage mascot for Captain America's regiment. He was later adapted to having been older. In the Ultimate Universe, Bucky was a paratrooper/war photographer who was a childhood friend of Steve Rogers, often having defended him from bullies. Fifty seven years after Steve Rogers fell into the ocean and shortly after Rogers was revived, Bucky had become an aging, cancer-ridden veteran and he married Rogers' wartime girlfriend.
 * Bucky's codename is Winter Soldier, much like his older self in the comics.
 * Notice that Bucky does not wear a mask like in the comics, and his identity isn't a secret.
 * Bucky used Captain America's shield, in the comics Bucky becomes Captain America when Steve was supposedly dead.
 * In the comics, Bucky was a trainer and lover of Black Widow, and the two have rekindled their relationship anandd remained steady since Bucky's resurrection.
 * The Winter Soldier is very similar to Rinzler/Tron from TRON: Legacy and Kingdom Hearts: Dream Drop Distance in that they were one best friends with a protagonist (Steve Rogers for Bucky, Kevin Flynn [and in Kingdom Hearts 2, Sora] for Tron) and were seemingly killed in a batle (Bucky was seemingly killed when he broke into the Red Skull's train, whereas Tron was seemingly derezzed during CLU 2's coup), but later revealed to have been brainwashed into a masked assassin.