Bucky does tense up when Steve comes in at him, but he doesn't duck away, and after a second or two of the kiss then he relaxes into it with a tiny smile that Steve can probably feel against his lips.

He can't help but be a little afraid that this is just another dream that his mind has cooked up in captivity to help him from going insane. It's nuts enough, with Norse gods and other worlds, and having his best friend love him back. He really fucking hopes it's not a dream, and Steve's lips feel awfully real against his.

"Since when did you get so bold?"

It's said with a proper smile when the kiss breaks.

"Not complaining, just asking."