Miles Straume (Ken Leung) originally appeared in "Lost" as one of the members of the expedition team from the freighter Kahana. He met the survivors of Oceanic 815 after parachuting on the island and it was soon discovered that he was a spiritualist with the ability to receive messages from the dead. His mission as part of the expedition was to capture Ben Linus (Michael Emerson) for Charles Widmore (Alan Dale), but he offered to tell his employer that Ben was dead in exchange for $3.2million, which was double what he was being paid.
While the survivors were planning to escape from the island, Miles decided to stay behind. When Ben moved the island, Miles traveled through time finally arriving in the 1970s where he joined the DHARMA Initiative. As part of the DHARMA Initiative, he worked on the security team under James "Sawyer" Ford (Josh Holloway). It was later revealed that Miles' parents were both part of the DHARMA Initiative and in 1977, he was present on the island both as an adult and a baby.
After the survivors of Oceanic 815 returned to the island, Miles assisted Jack Shephard (Matthew Fox) with the plan to change the future. This was to be done by detonating a nuclear bomb at the Swan construction site. After confessing his identity to his father, Miles changed the future by saving his father's life. After the bomb exploded, Miles was transported back to 2007, where he was abducted by "The Others" and taken to the temple, where he stayed until the massacre. After the massacre, he was rescued by Ilana (Zuleikha Robinson) and journeyed to the beach where he "read" the ashes of Jacob (Mark Pellegrino) and confirmed that Ben had killed him. He then visited the graves of Nikki (Kiele Sanchez) and Paulo (Rodrigo Santoro) and recovered the diamonds that had been buried there.
After Ilana died, Miles joined Richard Alport (Nestor Carbonell) and Ben on a mission to destroy the Ajira plane. This was to prevent the Man in Black (Terry O'Quinn) from leaving the island. Upon meeting Widmore again, they were told that the plane was booby-trapped. Miles fled when the Man in Black arrived and met up with Richard and Frank Lapidus (Jeff Fahey). They managed to repair the plane and fled the island with Claire Littleton (Emilie du Ravin), Sawyer and Kate Austin (Evangeline Lilly).
In the alternative, flash-sideways, shown throughout the last season, Miles was a Los Angeles detective who was partnered with Sawyer.
"This conversation already happened, we just don't remember it."
"Well, I lived in these houses 30 years before you did, otherwise known as last week."