The writer's guide described Sun:
The daughter of a wealthy South Korean auto parts magnate, Sun went to
college and fell in love with free-spirited fellow student Jin. After their
marriage, Jin changed, eventually becoming harsh and distant as he
relegated Sun to give up her own aspirations in favor of a more traditional
life in other words, a glorified servant). This forced Sun to devise an "exit strategy"- For the past two years she has secretly been
LEARNING ENGLISH. planning to ditch Jin in Los Angeles to stay
with a cousin, Sun's skills with Eastem Medicine may just be her ticket to
a new life. The plane crash has shattered Sun's plan, but not her resolve.
Now freed of the cultural and familial chains which have kept her
passive, Sun's evolution as an independent woman has officially begun.
The Sun-Jin island story was supposed to be able a "love conquers all" type tale. Even if they were not going to fit into the main group, they would always have each other. And that is all they needed in order to survive or be happy. In some ways, this story was actually adopted better by the Bernard and Rose story line.
The guide did tell of Sun's unhappy marriage, and her plan to leave Jin for a new life in America (even though the complex legal immigration issues were never resolved in any story; you just can't show up and stay in U.S.).
But her back story changed significantly. First, Sun went to college and fell in love with another free spirit in Jin. In the series, Jin's back story was much harsher: the bastard son of a lowly poor fisherman, Jin had no education - - - he left to the city to become a laborer, a door man, seeking a better life. He was not a free spirit, but a traditionalist. Second, in the guide Sun has her own aspirations in medicine, but in the actual story, we are given no life goal motivation for Sun other than being the heiress to a large fortune, and being rebellious against her father. Her relationship with Jin was more as a stab at her father than actual love. Third, it would seem that Sun "independence" on the island would have strained her relationship with Jin, and her English betray him to further isolation away from the group and her.
The guide places Sun in the role of the modern woman bucking tradition to follow her own path. It is not a love story but one of personal growth over the expectations of others. Her ideas of Eastern Medicine would conflict with Jack's Western approach, so there could have been conflict in the group on who was going to be the healer. Or, it would have led to another form of frustration, since Jack was a doctor and Sun was a foreigner, her skills would be dismissed out of hand by many castaways. This would have lead to further loneliness in Sun's character, which was a main theme of the series.
The writer's guide begins to shape the lower main characters as having personal "plans" to change their situation in life. In Sun's case, it was not divorce her husband but to ditch him in LA. She would start a new life on her own in a new, strange country, with little means of support except for a cousin. Like many plans, including Locke's, it is more based in fantasy than the practical specifics of reality. The guide does express Sun's emotional state by stating her culture and family were "chains" holding her back from becoming true self.
In LOST, Sun had bouts of independence, but in the end she reverted to a sentimental character of being Jin's loving wife which was not contemplated in the original writer's guide.
