It's never enough. Nothing B can do is ever enough. He heaves a shuddery little sigh, turns his face further into Steve's shoulder, and says quietly, "We'll remember. We're both really good at that."

Not just from the serum. They've both lost so much. They're the only ones left from their time, from their war, in a way from their universes. Since neither of them is ever going back. They've got a lot to remember. It's not enough, but it's something they can do.