Steve held Bucky to the ground, pinning him even though he wasn't really struggling too much against him. He didn't want something like that to happen again, so he did his best to make sure that he couldn't get out of his grasp. Steve still didn't understand why he reacted like that, but he was going to get answers out of him this time.

He was willing to let some things go unanswered, but not this. Not when he could've killed Tony.

"Stop struggling."