He knew the instant Natasha got cut because he received a slice of his own. His fingers twitched in her hand as the invisible blade cut into his side, carving a long, shallow wound that immediately welled blood. Steve turned his head a bit to see Natasha's face, a faint, sad smile on his face.

"You too? Where did it catch you? Let me see? Please?" Not that he planned to show his own wound, but that was a different issue. If they were both going to be cut up after all, he'd bite the bullet and do as she asked. It was the very least he could do.