Steve stopped the instant Bucky stiffened - his goal wasn't to frighten his friend, but to make him feel more at ease (which was feeling pretty impossible right now). And Bucky wasn't the only one that jumped a little when JARVIS interrupted, as it was - Steve blinked, looking around, although of course there wasn't actually a physical presence that he could address. So instead, he just tried to project his voice upward, as calmly as possible. "Can you?" He hadn't thought of that. "I... don't understand Russian at all, and I don't think he's processing English."

And clearly that wasn't good, not by the way Bucky's face was pale, the way he was practically vibrating with fear and visibly trying to keep himself silent. "It's okay to talk," Steve said gently, wishing JARVIS might be able to translate in a comforting tone, though he wasn't sure that was really possible for an AI - let alone one created by Tony Stark. "I'm not going to hurt you. I'm just here to keep you company."