When Steve finds Bucky on that table at Hydra he's been blinded (permanently or temporarily is up to you) so when Steve saves him he doesn't trust this bulky stranger with Steve's voice, or at least not fully. How can he reconcile that this really is his Steve if he can see him?

My preference is for angsty-missing-his-Stevie!Bucky gradually coming to terms with Steve's new body, believing that it really is him and lots of running-my-hands-over-you-to-learn-your-new-body.