I think that Michael has killed in a misguided effort to help his son. He may think that he is going to free him. Or he may have "gone over" to the "Other" side.

It does not matter because my theory is that Walt and and Claire's son Aaron are the main focus of the others. With the powers that Walt has shown, and the effort of Ethan to get Aaron there is no doubt about it.

Also remember all the things that "mind reader" from Australia said about, "having to be on THAT flight."

The Others want all of the children, but Walt and Aaron figure in their plans big time.

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I will tell you the truth at all times, unless I am pulling your leg.