Simon
Simon Tam joined the crew when he paid for passage on Persephone, bringing with him some rather important cargo. After a run in with another passenger who turned out to be an Alliance agent, it was revealed that he was a fugitive who had spirited his sister away from an Alliance facility.
Before becoming a wanted man, Simon was a talented young surgeon on Osiris having finished top 3% of his class and completing his internship in just 8 months. However, on discovering hidden messages sent in letters from River he threw himself into finding a way of getting her out.
He clearly felt responsible for River in using his not inconsiderable wealth in a plan to rescue her from the place that his family initially thought was a school for gifted children. After his fugitive status has been discovered, Simon strikes a bargain with Mal to serve as ships medic.
He doesn't really socialize with the rest of the crew, preferring to spend his time trying to find out what had been done to his sister. He has a rather antagonistic relationship with Mal and has an outright disliking for Jayne. He also has feelings for Kaylee, but his preoccupation with River and his ineptness at talking to women has so far ensured that nothing has happened between them.
