Bucky followed, and waited until they were in the lab, both of them seated, before he spoke again. He tried not to touch anything, resting his hands on the table and scowling at them. "I know it won't make anything easier on you, but you deserve to know," he says softly.

"During the war, Howard worked closely with us, with all the Howling Commandos. He was brave and stupid and terrifyingly smart." His mouth twists into a grimace. "He was my friend." His hands curl into fists as he fights down the nausea, takes a deep breath to steady himself.

He knows what he's saying will make Tony hate him. It should. It should make everyone on this whole god forsaken train hate him. The tears burn in his eyes, and he can't even look away from the one little stain on the table that he's focused in on. There's nothing else in the whole world, until he says it.

"He knew it was me."