James "Bucky" Barnes

Professional Marker: Bucky has a peculiar habit of killing his victims with a shot directly to the left eye socket - a signature Winter Soldier signature that reveals his involvement even decades later.
Reality Control: He constantly carries a small notebook with a list of the names of people he has harmed. This is his way of maintaining a connection to reality and attempting to atone for his guilt. He methodically crosses out the names of those he has helped (for example, helping an elderly museum curator recover paintings he once stole).
Social adaptation: After healing, he developed a number of everyday rituals to combat anxiety: he prefers to sit with his back to the wall to control entry, avoids loud sounds and sudden movements of strangers, and carefully monitors the cleanliness of his prosthesis.
Attitude towards technology: Distrusts modern gadgets, preferring the tried-and-true weapons of World War II or the high-tech equipment of Black Panther.

In his youth: Tall (about 187 cm), athletically built, with dark hair and blue eyes, he had the classic Hollywood look of a war poster—the exact opposite of his friend Steve.
As the Winter Soldier: Due to cryogenic freezing, he appears significantly younger than his biological age. His left arm is replaced by a titanium prosthetic created from vibranium in Wakanda. He usually wears practical dark clothing, and his long hair is often tied back or hidden by a balaclava. After treatment in Wakanda, he wears simpler clothing, and his left arm is covered in a thin layer of vibranium, superficially resembling human flesh.

Before his transformation, Bucky was the classic "golden boy": confident, charming, the life of the party, and a protector of the weak (which Steve then represented). Life as the Winter Soldier completely shattered his personality. He became a withdrawn, traumatized man, suffering from severe post-traumatic stress disorder (PTSD) and a deep sense of guilt. He is taciturn, suspicious, and constantly analyzes his actions. Despite this, he retains an absolute devotion to those he considers family—first and foremost, Steve Rogers, and later, Shuri and the Maximoff sisters.

Early life: Born March 10, 1917, in Shelbyville, Indiana, he was the eldest of four children. His mother died early, and his father, a serviceman, was killed during a training camp in 1937. Left an orphan, James settled right in the military garrison, where he helped the soldiers and became their mascot, quickly mastering military discipline.
Meeting Steve Rogers: In the late 1930s, Bucky stood up for a skinny teenager named Steve Rogers, who was being robbed of his money by bullies. They became inseparable friends from then on.
World War II: After the attack on Pearl Harbor, Bucky joined the U.S. Army and was assigned to the 107th Infantry Regiment. His exceptional physical attributes made him a legend among the soldiers as an experienced sniper and saboteur, carrying out covert missions while Steve remained behind the lines.
Fall: In 1945, during an operation to capture Arnim Zola's train, the train crashed. Bucky fell into the abyss. His body was found by Soviet intelligence agents of the organization Hydra, near death. His left arm had been amputated and replaced with a high-tech prosthetic. Hydra erased his memory, implanted him with psychoprogramming, and froze him, turning him into the perfect ghost-killer codenamed the Winter Soldier.
Winter Soldier Era: For decades after the war, he carried out Hydra's most nefarious missions, assassinating political figures and causing global crises (such as orchestrating the assassination of John F. Kennedy). Between missions, he was placed in cryosleep. A key moment was the murder of Tony Stark's parents, which Bucky carried out under orders from Howard Stark, who was under Hydra's control.
Path to Redemption: His memory began to return after his confrontations with Steve Rogers in Captain America: The Winter Soldier and Captain America: Civil War. Realizing his guilt, he voluntarily returned to cryosleep in Wakanda. There, King T'Challa helped him remove the Hydra program. To make amends, Bucky fought against Thanos in the Battle of Wakanda and the final confrontation (Avengers: Infinity War, Endgame), but it was only after these events that he became a full member of the team.