It happens so fast that even Steve’s heightened reflexes don’t have time to react. Bucky’s breath is coming quickly as Fitz helps him into his seat; his face is white from blood loss, pupils dilated, and then Fitz is staggering backwards with a shout and Steve’s heart is sinking through the floor.
Bucky still can’t cope with medical treatment. Steve had hoped that multiple shattered ribs and a bullet wound to the gut might convince him to acknowledge the necessity of being treated, but - well.
"I’m - I’m fine," Fitz pants, catching his balance on the wall beside him. "It’s fine, Agent May. Please." On Coulson’s nod May lowers her gun, but she doesn’t holster it. Coulson’s calm gaze turns on Steve, and Steve knows exactly how this ends: they’re going to have to sedate him, again, and when he comes back around he’ll be fully healed and half-panicked and vindicated all over again in his distrust.
And then - Steve is still staring, paralysed, praying to every god he’s heard of for a way out of this mess - then Simmons is shrugging off her lab coat and stepping forward, very slowly.
"For heaven’s sake, Fitz," she says. "You can’t just manhandle our patients like that. Are you alright, Sergeant Barnes?" The tension in the room spikes sharply as she steps closer, but Simmons doesn’t falter. "He must have jarred you, didn’t he? Those ribs of yours look very uncomfortable. Would you like a painkiller?"
Don’t mention drugs, Steve thinks, panic rising in his throat like bile. Bucky is terrified of being drugged. But he doesn’t lash out again, and Simmons makes no move to administer any medication - just tips out a white tablet into her hand and watches carefully for Bucky’s reaction.
His lips are closed tight, jaw clenched, eyes fixed on the pill like he expects it to leap up and hurl itself down his throat. “Actually,” says Simmons, “I think Fitz had better have one too. I think you sprained your wrist in that fall just now.”
"Not at all, I’m perfectly - oh, actually, yes. That does hurt a lot,” says Fitz, catching on only a split second before Steve does: these pills are safe. Look, we give them to our own team as well. And it works: once it becomes obvious that the pill isn’t doing Fitz and harm, Bucky takes his without a fuss. Simmons hangs back for a few quiet moments, lets him breathe. His posture relaxes a little. His eyes take on a slightly glazed look. He’s not calm, exactly, but whatever was in the pill he took has taken the edge off his panic. Just enough that he doesn’t flinch when Simmons steps closer again.
"There we go." Simmons smiles encouragingly, and then somehow - somehow, thank God, and Steve is going to buy Simmons the world’s biggest bouquet when this is over - Bucky isn’t fighting her. She keeps up a steady stream of chatter as she works, telling Bucky exactly what she’s doing, and by the time she’s finished her work Bucky’s breathing has slowed to almost normal and his right hand isn’t even shaking anymore.
It takes Fitz a while to sober up from the industrial strength painkiller, of course - but from the goofy grin on his face when he leaves the medical bay, he doesn’t seem to mind.