Jin's character was the outcast among outcasts. He had a language barrier so he could not communicate with his fellow castaways. He was suspicious of everyone around him. He was a traditionalist who wanted his wife, Sun, to obey and follow him. He would have found it acceptable to be on the outer limits of the beach camp, alone with Sun, rather than trying to integrate into the new community. Jin's story is like the story of an immigrant landing in a new country and trying to adapt to a new culture.
The writer's guide described Jin as:
Jin was born into an impoverished family in a fishing village in Southern Korea. After meeting Sun, the spirited daughter of the most powerful auto magnate in the country, ,Jin fell deeply in love. Unfortunately, due to a fierce class system, Sun's father refused to give his permission for the two to marry... unless of course Jin was willing to play ball. The result was a Faustian deal- Jin promising to keep Sun squarely within the strict confines of Korean society in exchange for a high-paying, high-ranking job. While the agreement afforded Jin VIP treatment, it left Sun betrayed. Jin is preoccupied by what he considers a far greater betrayal: his wife's INABILITY TO CONCEIVE. On the island his own inability to communicate with the others is balanced by his knowledge of the oceanand his knack for capturing marine life for food... but when he realizes he must now rely on his wife, he must choose between attempting to regain her love or fall prey to the dangerous allure of the island's dark influence.
Jin's story was always going to be tied to Sun's story. Whether it was going to be a take on modern or traditional marriage, the issues between couples, or stories of lost loves . . . the two would be paired in their actions and events on the island.
Jin's guide story tracks what was shown in LOST (to a degree): born to a poor fishing family, he leaves his family to find fortune (in Sun's back story in college). He falls for Sun, but cannot marry her without making a deal with the devil, Sun's father. He must change his plans and become a company man in order to marry Sun. Jin bows to tradition. As a result, Jin demands what is expected of his subservient wife, children. But Sun cannot conceive, which Jin considers a betrayal to him (since she married him only to get back at her father and not have a true family with him).
So Jin's dilemma parallels the actual story line show in LOST: his conflict that he apparently married Sun for the wrong reasons, and he was caught like a fish in a trap, at the mercy of others like Sun's father or cultural demands upon him. We also see that Jin's skills on the island were quickly dismissed by the other castaways, who did not want to eat "foreign" food. He becomes quickly isolated, but for his marital bond with Sun.
In the guide, that marital bond with Sun would quickly collapse, leaving Jin totally isolated on the island. He would view from a far when Sun takes her English language skills and becomes an active member in the beach camp. Her happiness of being accepted by new people who respect her and her talents, would make Jin angry, depressed and lonely. His only hope for emotional survival would be to regain the trust and love of Sun. He would have to plan to woo her back.
But the writers add an entirely new element in the guide, especially as it relates to Jin (with application to any other person on the island): fall prey to the dangerous allure of the island's dark influence. The idea that the island has a "dark influence" over people is an agent of change that could dramatically affect relationships, bonds or even life and death decisions. The darkness could be the evilinside all primordial instincts and fears that could be released in the unchecked lawless society that is the island (survival of the fittest).
The concept of the characters having an opportunity to "change" themselves and live out their dreams because the plane crash has given them a second chance is a prime motivation to action, but if the island has its own, involuntarily, sway over character actions (dark influence) that could have been a devilish monkey-wrench in any decision making process. For example, crime without punishment. Some may consider this as a vague reference to the smoke monster's ability to shape shift, read memories, and create ghosts on the island to manipulate the feelings and actions of the candidates. That could be a fair assessment of a dark influence, but it would seem that the writers' premise would be that the island itself harbors something that would trigger dark thoughts in any human (i.e. sort of more like the vague "infection" story arc).
Of course, the motivation of Jin to have a traditional family after being spurned by Sun could have led to the ultimate emotional double cross - -Jin fathering a child on the island with another woman. Would have Sun felt betrayed by Jin's actions? Would she have had an emotional melt down if Jin found happiness and her new independence was not all that it was cracked up to be? That would have created a more layered story line between these two characters than the one ultimately shown in the series.
In the series, Sun and Jin are not really main characters. They are secondary people whose job is to help more important characters do specific tasks. For example, Jin became Sawyer's deputy. Sun began a gardener and nurse to Jack. Their story lines act more as filler than as key moments in island events. Again, the producers and writers made a conscious decision early on in the series to down play the Jin-Sun story.