Even pumping blood from one shoulder and bruised from Loki's spearhaft, he's too solid to go down, but the impact makes him wobble. When Darcy dives for him all Steve can do is yell "No!" with all the panic and hopeless desperation of someone convinced they're about to see another friend die inches away.

And then Loki... stops.

Steve has his hand on Darcy's shoulder arm and it half-way to throwing her out of the way when Loki does, and he just sort of... leaves his hand there as she points that arm at Loki and talks like her accusation means something.

Steve is so, so confused. "Darcy..."

He sways and drops down on one knee, his hand still on her arm. He has to get her out of here. First, though, that means getting her to listen to him.