He like O'mara was another character that went from a no name to Actually becoming a flushed out member of the Raptors crew. His design has changed a little over the years but i'm happy with this finalized look. He was originally supposed to be the Ratpor's Commander but that didn't work out. He is Harry's Current first officer and runs the Ops station since he's familiar with most of the crew and the ships operations. They have a a grudging respect for each other and Rivas tries to keep a professional candor with Harry although occasionally they have had words with each other