When Steve finally managed to persuade the ex-Winter Soldier to return with him to the Tower, Bucky haunted the building. He rarely spoke, but unless someone startled him or triggered a flashback, he wasn’t hostile towards anyone either. JARVIS reported that he did occasionally hold conversations with him, finding it easier to speak to the disembodied voice than the Avengers.
Steve was still sad that his friend was staying so separate from the group, but he tried to be as patient as he could be. The other Avengers do notice how Bucky flinches slightly sometimes when Steve talks about their childhood and growing up together, but when Natasha asks him if he wants Steve to stop, Bucky tells her to leave it be.
Then JARVIS alerts them that Brock Rumlow, aka Crossbones, appeared on SHIELD’s radar again, and Bucky insists on coming on the mission.
When Rumlow, Steve, and Bucky all end up facing off while Hydra agents keep the other Avengers busy, Rumlow tells Steve how “his Bucky” remembered him after their first fight, before being wiped again.
It sends Steve nearly into a rage, until Rumlow flees with the few surviving agents, leaving Bucky behind, his face pinched.
He doesn’t say anything on the ride back to the Tower, and then disappears as soon as they land.
Steve keeps trying to lure him out, and finally succeeds when the Avengers have a movie night. Bucky sits in the back of the room, however, nearest the door, and he’s gone as soon as the credits roll.
He doesn’t hide from the group again, though, and several days later, Steve is telling the other Avengers a story of how Bucky saved him and the Howling Commandos, when Bucky snaps.
“Steve, I know you wish I were just like the Bucky you grew up with,” he half-shouts, half-growls, “but I don’t. I hate him!”
Bucky stands so quickly, he topples over the chair he was sitting in, and is out of the room before anyone can blink, leaving very confused Avengers in his wake.
What they didn’t know, was this:
Bucky was only ten the first time it happened.
It was a small thing, fetching protection money for a local gang. They liked hiring kids, since the store owners would rarely hurt them.
He did it for the money, so he could buy medicine for his sisters.
He did it again more regularly when there wasn’t enough food on the table, and it became a steady job when Steve’s mother became ill.
As he grew older, the store owners would throw punches or worse. He told Steve he got in a fight protecting someone, and joked that Steve was rubbing off on him.
Within a few weeks of turning eighteen, he’d hit a second growth spurt and started working out, putting on weight. He’d left the gang when the police began taking them down, and the local mob had snatched him up immediately. They used him as an enforcer, sending him after anyone who missed protection payments.
At home, Steve began talking about the army.
Shortly afterward, a group called Hydra approached him. They offered him more money than the mob, even if the jobs are darker. He accepted, and told Steve he got a better-paying job at the docks.
By the time Bucky was drafted, he’d started to enjoy the double life, even if it meant lying to his best friend.
He knew Steve would never understand, but he found he didn’t particularly care.
Bucky knew it was over when he joined the army, however.
Then Hydra, and Zola, got his hands on them. He never learned exactly what they did to him before Steve showed up, more than a foot taller and a hundred pounds heavier, but after that, the anger inside him was always closer to the surface.
He did a decent job of hiding it, and Steve chalked it up to having been tortured or experimented on, or just being hardened by war.
It was only weeks later, when he was watching Steve and the other Commandos through his sniper rifle, that he felt the first tug of a command.
Kill Captain America, a voice in his head said, and it sounded like Zola.
He buried the voice, and took out a Hydra agent aiming at Steve instead. Steve just gave him a salute as Bucky got ready for another shot, unaware.
It was the one thing he wouldn’t do. He knew he sold his soul, and when he was drunk, he could even admit to himself that he enjoyed the war, sometimes. It gave him somewhere to pour all the anger inside him.
But he won’t let them get Steve.
He took more risks than the other Commandos to protect their Captain, and it didn’t go unnoticed. It was obvious to everyone that Bucky valued Steve’s like over his own. Their superiors liked it, since it rose Captain America’s chances of survival even more.
Steve was less pleased. They fought more than once about it, but Bucky stood firm.
Then the train happened.
A Hydra agent aimed at Steve, and Bucky recognized him. He felt the pull to stand by and let Captain America die, ignored it, and grabbed the shield to save his friend.
When he fell, he guessed it was the price for all the bad he’d done, and liked.
But he didn’t die, and Hydra got their claws on him again, and this time, deeper. They took the remainder of his arm, and then stabbed them into his head. Zola said if he couldn’t follow their orders willingly, he didn’t need his will.
So they took it, and created the Winter Soldier.
When Bucky finally remembered his past, it took him a long time to realize his memories were true and Steve’s stories were missing a lot. Then he hated the old Bucky, for how he’d enjoyed the violence that the new Bucky had to fight so hard to suppress.
The new Bucky didn’t want to be like the old version.
He wanted to be good.