Full Name: Sun-Soo Kwon, nee Paik
Reason for trip: Vacation trip with husband, Jin
Profession: Housewife
Island relationship: Married to Jin

Jin's wife, Sun-Soo Kwon came to the island by accident, after nearly leaving her husband. Her marriage began with great promise, as Jin managed to convince her wealthy father, Mr. Paik, of his intentions. Unbeknownst to Sun, however, her father had placed a significant burden on Jin by demanding he come work for him. Over time, Jin became distant and abusive, and, seeking to escape her failing marriage, Sun began taking English lessons in secret. Finally, with the help of a friend, Sun was given a chance to escape her husband while at the Sydney airport. A single moment of tenderness from Jin while waiting in the check-in line reminded her of her love for him, and she decided not to leave him at the last minute.

On the island, she was initially suppressed by Jin, who felt it was his job to protect the two of them from the other survivors. However, over time, as Jin's attitudes brought the couple into conflict with the others, she began to assert herself, and has since become a very important contributor to the lives of the survivors. Her knowledge of herbal medicine made from plants and wildlife found throughout the island has proven very valuable in a number of instances. She and Kate are growing a vegetable garden with some of the herbs that she has found to be useful for curing common ailments. She has also proven an able medical assistant to Jack, including recommending the use of sea urchin quills to pierce Jack's skin in order to transfuse his blood into Boone, and has been a voice of calm and reason when some people begin to go too far. Unfortunately, her freedom has come at a price: when Jin found out that she had been keeping her English language knowledge a secret, he told her that their marriage was over, and has since refused to speak to her.

On Kate's advice, the day before the second raft was scheduled to leave the island, Sun poisoned Jin's water. But Michael drank the water instead, and fell ill. Only Jack, Sun and Kate know that Sun is responsible for the poisoning.

Prior to Jin's departure on the raft, he and Sun reconciled.