He could have behaved as Zemo sucked him off, relatively keeping himself in line. That mouth of his, if it kept going like that, definitely would get him to that happy ending. But when Zemo replaced his tongue with his hand, the rough contrast between the two turned his stomach inside-out and he almost fell back into the bed at the sudden change in intensity. Bucky knew he wouldn't be able to restrain himself after that. He let out a strangled moan, then a very happy noise when Zemo's hand found its own rhythm. Bucky was nearly disappointed when Zemo made the switch back.
But not for long. Zemo continued on with the same fervor as he'd started with his hand. If his goal was to tear his dear soldat apart by the seams, he was well on the way there. Bucky could feel everything inside of him rush to his center, pleasure trickling under his skin. At moments, it was hard to think. Especially whenever he could feel the ridges of Zemo's tongue brush against the side of his cock in the most delicious way.
He slid his hand through Zemo's hair again, twisted his fingers around what he could. Short nails scraped the skin as he collected a firm grip. His hips lifted off the bed briefly as he bucked slightly into Zemo's mouth, testing his resistence. Not that it would matter soon, Bucky thought wickedly. He smirked down at Zemo, those nails scratching behind his ear affectionately. "You ready to see what someone can do with leverage?"
That first thrust was hard and unkind. He held onto Zemo's head as he forced himself in deep. And he was fast, never intending to cut Zemo's air off entirely ...yet. In and out, keeping his grip steady in Zemo's hair. Too many times he forgot to breathe himself and when he did remember that, he forgot about trying to be quiet.