Rudy Buenaventura was Bucky's father.
Rudy and his wife Gloria were inventors, and passed that trait on to their son Bucky. Bucky was smarter than either of them, and he had to fix all of their inventions. Unable to raise him, Rudy and Gloria put him away at the Sorben Institute as soon as he was old enough.
Donald Tannor kidnapped the Buenaventuras in the hope of fixing his rejuvenation spa. They weren't helpful, and were turned into children themselves. Tannor decided to hold them for ransom to force Bucky to help him instead.