Shannon had a reverse daddy issue. Her father spoiled her. He gave her money. He protected her against the real world. He got her out of trouble. When he remarried, he was the buffer between his daughter and her step-mother. But when in the emergency room, Jack made the choice to "save" Sarah instead of Shannon's father (since both were critically injured), this set Shannon's life on a slow, downward deadspin.
It appears she never held a real job. Being a cute girlfriend, a rich bitch or a party girl were not lasting career choices. She did have the gift of flirtation and sexual promise. But as in the series itself, she was more a cardboard cut-out, a centerfold without a soul, a wasted opportunity to have an interesting life story.
After her father passed away, Shannon was left on a family island. Her stepmother treated her poorly. She was put down. She had no place in the family business. Shannon was not a hard worker because her old life had been handed to her. Without a drive, personal goals or dreams she would wander aimlessly from bad boyfriend to bad relationship.
Lostpedia summarized her as follows:
Before the (Flight 815) crash, her father had died in a car crash and she had been cut off by her stepmother, who also refused to give her any of her father's money. She used men, especially Boone, to get what she wanted, which eventually led to a one night-stand with Boone. After the crash, she was very selfish at times, refusing to help the other survivors, as she insisted they would be rescued. However, she assisted in trying to get a signal on the transceiver, and used her French skills to translate Rousseau's signal. She also had an asthma attack when her inhaler ran out, but Sun eased her symptoms. She eventually formed a romantic relationship with Sayid which helped her realize her selfishness and led to a change in attitude. As she and Sayid went for a picnic, Boone fell out of a plane and died of injuries. After Boone died, Shannon sought revenge on John Locke, attempting to shoot him, but Sayid interfered. She eventually forgave Sayid, but began to have strange visions of Walt who she thought was on the raft. On Day 48 she ran from camp with Sayid to search for Walt; however she collided with the Tailies and was unintentionally shot in the stomach and killed by Ana Lucia Cortez after chasing another image of Walt. She died in Sayid's arms having finally gained his confidence and belief in her.
Many viewers did not find Shannon's character compelling; many felt that the death scene was merely an actor's clip reel (since so many of the characters would succumb in the next episodes). She was a "taker" and not a giver. She had to rely on other people (Boone, Sun, Sayid) in order to cope with the very basic daily routines most people take for granted. Her loss was not taken as a great defining moment in the series.
Even after her death, her character drew ire from some fans. Why would a week long island affair be more important to Sayid than his lifelong quest to find his true love, Nadia? When Sayid wound up with Shannon in the after life, most fans were disillusioned because it really made no sense. Shannon had made no great leap or redemption in the sideways world to merit "a reward" of companionship in the next world. Further, it upset people that Shannon got what she wanted (a man to care for her forever) while Boone sat alone in the sideways church. Boone, the guy who cared and loved Shannon, and who died trying to get her rescued, got nothing for his effort.
It is a sad commentary that Shannon, the spoiled rich girl can be the Cinderella in the end by not doing anything.
