Before the Crash
Dexter tells Jack that when he was younger, he was on his Cousin Jay's yacht when he forgot to pack the cooler, which was a disaster for Dexter as he claimed to be prone to dehydration. His cousin offered him $1000 if he stayed alive until they reached the marina as his face had turned bright red and his cousin thought he was going to die. They were 1 hour out into the bay when they realized they had no cooler.
Dexter had a bad encounter with a bully when he was in the fourth grade. He was jumped on by the bully and received a bloody nose, black eye and a cracked head.
Dexter fell off a horse when trying to learn how to play polo, but claimed he wasn't any good at the sport: Damn horse tossed me right into the goalpost.
His aunt received a great deal of money from a 'legal dispute', and sponsored his college tuition. He went to an unknown Ivy league school, where he studied Psychology as well as British Literature, Economics, Chemistry and Spanish. While there, he met his dream wife, Daisy Ward, on campus. He pretended that he was from a wealthy background to keep her, and the plan worked. He went to a trip to Australia with Daisy, her brother Jason and her parents. While in Australia with Daisy and Jason, after their parents had gone home on an earlier flight, Daisy was mugged. Jason asked Dexter if he could pay for the rest of the trip. It was at this point that Dexter was forced to reveal that his family was not wealthy and that he had been lying to Daisy and her family.
On the Island
After the crash, Dexter made some connections with the other survivors. He met Leslie Arzt and became friends with Shannon and Boone. He was one of the many injured survivors of Oceanic Flight 815, and did not hear the Monster on Day 1.
He fervently searched The Island for Daisy, which consumed a lot of his time on the Island. He even dared to enter the fuselage, with dead bodies inside, but didn't find her (but he did find Sawyer, stealing things from the fuselage). It is unclear if she was even on the plane or if she had cancelled that flight because of their fight in Sydney. He did, however, find his girlfriend's brother dead in the jungle. He is revealed as Dexter Stubbs when George finds his suitcase with the name Dexter Stubbs on it.
- He is named Dexter Stubbs, but adopted the name "Cross" from a brand of soup, as the image on the cans had always implied wealth to him. His amnesia from the crash led him to believe his stories of being wealthy were true, and so he became "Cross" rather than "Stubbs".
- The character seems to be an homage to Jay Gatsby in F. Scott Fitzgerald's novel, "The Great Gatsby". Many similarities - attending a prestigious college, falling in love with a wealthier woman named Daisy and assuming a new, wealthy identity to woo her, even his cousin's name Jay - reference The Great Gatsby.
- Dexter Stubbs has no relation to Charlie's ring. The 'D.S.' on that ring refers to the similarly named Dexter Stratton.
- For fan theories about these unanswered questions, see: Dexter Stubbs/Theories
- Who is Dexter's father?