"Hey, awesome," he heard Iron Man saying, and even through the distortion caused by the voice modulator, Bucky could tell something was wrong. "You’re awake."
With an effort, Bucky managed to open his eyes, tried to sit up, but hit an unexpected wall of pain. Hissed, body jerking reflexively, his heels digging into the ground as he attempted to move, and failed.
This is a great example of comedy putting tragedy and suspence in stark relief. Bucky desperately tries to keep Tony awake and thinking and their good humour barely misses a beat, exposing their fear only more powerfully as the situation grows more dire.
Great - Bucky is confident, aware of himself and so alive; you can see him keeping up with Tony at every turn, just by watching their one desperate moment.