Shannon's dad was the man driving the vehicle that hit Jack's paralized patient, and future wife, Sarah. They refer to the man that hit her by his last name, which is the same as Shannon's last name. Then, if you watch carefully, when the doctor is telling Shannon (and her stepmom) that her dad is dead, Jack is walking by in the background, coming from the room where he first encountered a critically wounded Sarah. Certainly, her father's death leaves Shannon in a horrible position with her wicked stepmother. So yes, you could say that Jack's decision inadvertantly led to Shannon's bitterness. In another interesting twist, Sawyer was the one who bought the round of drinks that led to the death of Jack's dad, Christian, in the Australian bar. Christian had left his wallet in the motel room, so Sawyer offered to buy his drinks. So Sawyer inadvertantly provoked Jack's bitterness over his father dying without reconciling with Jack. Turn about is fair play?

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