The most important character to the story is in limbo right now. Why didn't Head-Six show up when Baltar was near death on the rebel Base Ship? Is she the center of the universe? Will she fade away? Is she just a number? A literal angel? If the end is the beginning, Six must be there.
Kudos must be given to actress Tricia Helfer who has played the Six character. Cast in the show with limited acting experience and a background as a model she was tasked with creating multiple characters (sometimes for the same scene) and has excelled in the part, holding her own alongside seasoned and talented veterans such as Mary McDonnell, Michael Hogan, Edward James Olmos and the scenery-chewing James Callis. It is the depth and nuance she brings to her performance(s) which has anchored the show.