From Tv Guide

First, on Lost, we’ll learn that Jacob—soon to have a confrontation with Jack—may not be so godly after all when his character takes center stage in “Across the Sea” on May 11 (followed a week later by the penultimate “What They Died For”). “Jacob has a lot of darkness and corners we haven’t explored yet, so the differences between him and Lucifer are not as much as you would think,” says Mark, an L.A. native who shares a passion for martial arts with Lost rival/real-life chum Titus Welliver (Man in Black). “With these archetypal characters, the boundary between good and evil becomes blurry. Jacob’s on a mission. It’s your judgment as to whether he’s good or bad.”



source: TvGuide