Simon Tam is a highly intelligent, well-to-do young surgeon whose life has been completely turned upside-down. After discovering that his beloved younger sister, River, was being harmed at an Alliance-run school, Simon spent 2 years attempting to get her away from there, being set adrift by his father along the way.
Eventually, with 'luck, and lots of money', he was able to pick up the cryogenically-frozen River on Persephone. The ship he chose to take them off-planet was Serenity.
After River was nearly turned back over to the Alliance by a mole, Simon was offered a position on Serenity as the ship's doctor. He and Captain Malcom Reynolds did not trust each other, but they have developed a grudging respect for each other. As Mal said, "Doctor could be called a lot of things. Coward wouldn't be one of 'em, though."
When Mal came back for him and River on Jiangyin after they were kidnapped by the hill folk, Simon began to realize that being 'one of my crew' has deep meaning to Mal, and his trust in the Captain began to grow.
Though he still does not like him, Simon has the beginnings of a misplaced respect for Jayne. Having no clue that it was the mercenary who tipped the Feds off while they were on Ariel, he believes that everything Jayne did was to save him and his sister. Mal has chosen to keep his knowledge of the true nature of the debacle to himself, having made it abundantly clear to Jayne that "you turn on ANY of my crew, you turn on me".
Now Simon is concentrating on trying to heal the damage that the Alliance did to his sister's brain when they stripped her amygdala, and on slowly fumbling his way to a possible romance with Kaylee. He's not doing very well. ;)
http://www.fox.com/firefly The best board ever! :)
http://www.twoevilmonks.org (the two larger pics were from here) Great site with lots of screencaps and hysterical captions. :)