Bucky shook his head. "No. Thank you." He didn't want to be rude but he also didn't know anything about what Dean was offering him and didn't want to choose that moment to figure out how it may or may not react with a super-soldier. And, though he didn't particularly want to admit it, Dean catching on that he was in pain, to begin with, put him on edge. He'd spent most of his life shielding things like that from the world and, most of the time, people couldn't figure him out. He didn't like that he'd been read so easily and it made him want to shut down further. "I'm fine."