"Harder," Bucky instructs, and when Sam does he slowly spreads his fingers apart. "Just like that, keep it up." Reaches for that spot inside and rubs against it a little. The noise Sam makes in response drives his cock to jump against Sam's lap as Bucky covers Sam's mouth with his free hand.

"Breathe. Relax." Sliding his fingers out and wiping the slick on his own cock before he coaxes Sam to arrange himself further forward, so that he can enter him again. He kisses Sam through the intrusion, swallows every sweet and plaintive sound Sam makes into his mouth. "Squeeze again. As hard as you can, then breathe out and relax." Which will allow Bucky to get even deeper. "Shit, baby, you feel amazing."