It's been two days since Natasha was shot. Two days since Tony's hand was the one that pulled the trigger. Two days since it felt like reality has shifted, but Steve still can't put his finger on why.

He's never been someone who was so serious that he could never joke, or smile. Steve saved that part of him for missions, when he needed to maintain complete focus so he and his team could accomplish what he'd set out to do. Still, even back then, an occasional smile could still manage to peek through. But for two days now, Steve's felt like some part of him has been turned off. That he's lost the ability to feel levity and instead, all he knows is a stern determination to fix what happened. He has to figure it out.

There are too many dangerous questions with unknown answers. When did Tony's conditioning start? Who is trying to kill Natasha? Does any of this have something to do with the mod killings?

And of course, Steve would be lying if he said that there wasn't a part of him that was always worried about Tony. But he tries not to think of that now, as he stands in front of Romanoff's door, knocking. There are things he'd like to tell her, and the rest ... the rest will just have to wait.

"It's me, Steve," he says, as if Natasha wouldn't be able to recognize him by his knock alone.