Skate.

What you saw on television, the show itself, was the ten percent of the 'iceberg' above the water. But the majority of our time in the writer's room was spent constructing the part below it. The details. The timeliness. The intricate backstories... -Darlton

That is an excerpt from the forward provided by Damon Lindelof and Carlton Cuse for the official LOST Encyclopedia. I happen to own that glorious book and I thought I'd take a minute and share with you the parts that included Skate.

Sawyer's section on Kate's page
Both killers, criminals, and con artists, Kate and Sawyer were kindred spirits,...