Michael is defintely working for the others. He killed Libby and Ana to free Henry. Obviously he is doing this because he has turned or he has been given an ultimatum to get his son back. The hanger here is how long will it take the losties to figure out that he did it? And when they do find out......what do they do to Michael?

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a beach is a place where a man can feel he's the only soul in the world thats real. Quadrophenia