He watched Tony for a little while longer, but soon returned back to the boxes in front of him since everything seemed to be okay. Steve trusted that Tony knew what he was doing and he was probably the most capable person in fixing Bucky's arm, so he would leave him to that. Besides, Bucky looked okay at that moment. He just needed to concentrate on his task.

He thought everything was going well, he even found one of the things he needed. But that all changed when Steve suddenly heard a hissing sound coming from behind him.

Steve immediately dropped the object from his hand and turned back just in time to see his friend punch Tony in the face. And it wasn't too softly either.

"Bucky!" He yelled as he ran towards the two, unsure why he would do something like that. But he needed to stop him... and probably get some ice for Tony soon.