In her apartment, Natasha anxiously poured tea into two cups. She gently handed one to Steve. "Here, Steve," she said. "Drink."
"Why are we sitting here, doing absolutely nothing and sipping…" -he took a sip- "green tea? We should be going after Bucky!"
"Tea is good for the spirits."
Steve knew when she was deflecting a question, and persisted.
"Because I'm telling you, he's not the man I knew anymore. And he's no longer your brother." If Natasha had been on her own, she would have gone after the Winter Soldier by herself, but Steve was with her now. That changed things. She didn't care what happened to her, but if Steve had any hope of getting out of this alive, he needed to rest first.
"I don't-"
Steve saw something different in Natasha's expression. There was the same death in her eyes that Clint Barton had described when Natasha was found on the beach, but there was also a certain solemnity to it. Natasha simply said that the Winter Soldier, or Bucky as he knew the man, had forgotten what love and family meant to him. If he killed them, he would not grieve, because he did not remember.
This was the only time that Natasha admitted she was afraid. Not for herself, but for her brother. Believing that this mission would be her last, Natasha decided to tell Steve the full story of her connection to his brother.
She had grown up under the system; fighting for the Motherland had been all she'd known her whole life. The Winter Soldier appeared when she was barely sixteen, and even though there were things about him that didn't make sense, she never questioned it; questions were acts of rebellion. Because she and the Winter Soldier were the top two in their class, they often trained the other recruits and went on difficult assignments together. They were supposed to be monsters: ruthless, efficient, and deadly. They would tally their kills and make light of the situation, because if you ever stopped to think about what you were actually doing, you would never get anything done. But sometimes, when Natasha would hesitate to kill, the Winter Soldier, for her sake, would spare the target's life without the KGB's knowledge (as far as they knew, anyway). He still retained some humanity, even if it was only out of his love for her.
"Why are you saying all this?" Steve was uneasy; Natasha seemed to think that she wasn't going to come out of this alive.
Natasha explained, because the Winter Soldier's emotions had been completely stripped away from him. If the Russians had brainwashed Bucky Barnes and turned him into the Winter Soldier, then they were certainly capable of reforming him into a mindless killing machine who only followed orders.
"I'll save him; I know it. But I'm scared of what he's become. I don't know what he's going to do anymore."
So they were stuck here. The Winter Soldier would come to them, instead. Natasha was sure he had found out where she lived anyway.
"There's just no other way."
After that, everything happened so fast.