©2010 Varèse Sarabande and Michael Giacchino
"Blood From a Locke" is an orchestral piece from the Season 6 soundtrack.
Jack tackles Locke as he leaves the source cave. He punches him, and Locke is surprised to find his lip bleeding. Locke then reaches for a rock, knocks Jack out, grabs his backpack and leaves.
The piece begins with Jack's motif. The second movement blends the Heart theme with the duel motif.
The title references the phrase "You can't get blood from a rock", which describes the futility of forcing an unwilling subject. In the scene, Jack manages to get blood from Locke.