Once Steve gets over the shock of seeing Bucky again, once he’s thinking about what Zola did, all he can hear echoing through his mind is
I should have known.
He should have known because when he pulled Bucky out of Zola’s lab, he could barely walk, but he marched back to base at Steve’s side, under his own power.
He should have known because none of the injuries Bucky suffered in the field took the way they ought to have.
He should have known because while the Howling Commandos fought their way through Europe, Bucky was always at his side, always keeping pace with him.
He should have known because Bucky shouldn’t have been able to keep up with him, and he always, always did.
He should have known, but he didn’t – because his whole life, he’d been trying to keep up with Bucky.
And it never once occurred to him that Bucky shouldn’t be able to keep up with a super soldier. Because Steve was the super soldier, and of course Bucky could keep up with Steve. Because Bucky had always been ahead of Steve, and Steve’s new body just meant he could catch up.
It just meant Steve and Bucky were finally side by side, just like they were always supposed to have been.
This hurt me.
And yet I accept it completely.
Not only that, you’ve got to think Steve is going to wonder why Bucky DIDN’T say anything to him. Bucky had to be aware SOMETHING was going on, even if he didn’t know what. And he chose not to tell Steve, more than likely from a combination of issues over Steve suddenly not exactly being STEVE, and also because Steve was pretty preoccupied. But that’s going to hurt Steve when he thinks about it, not only because he didn’t notice, but because Bucky didn’t confide in him. For whatever reason, Bucky shut him out there and that’s going to hurt. Steve’s going to wonder if maybe Bucky was hoping he’d notice and he didn’t. So many little signs Steve just didn’t notice because he always thought about Bucky a certain way and didn’t take into account he SHOULDN’T be able to do what he was doing.
And Steve is so smart. He’s able to pick up things so quickly. He knew something was happening with Bucky, but he didn’t push the issue. He didn’t really sit down with Bucky and try to get him to confide in him. He was fighting a war and time was vital, so when Bucky didn’t volunteer his issues, Steve didn’t press.
Not having a serious discussion with Bucky is going to hurt Steve.