The Time Travelers Father In Law…
Charles Widmore knows the future. Lets face it. He knows Locke was going to arrive off island…and he knows there is a war coming to the island…how does he know…because something changed that has yet to be seen.
Remember when Charles talks to Ben in his loft, and Ben asks when he started keeping a bottle of whiskey by the bed…and he said “When the nightmares started”…THAT is how I feel he is learning the future.
Charles brings Des to the island to go back in time and tell Charles’s younger self about the war that is coming…Young Charles then orders that purge, and upon learning of his off island future, begins leaving, makes another family and is eventually kicked off for it…maybe not in that order.
His loophole is Desmond. Des tells him of this in his past (being sure to point out that he will return to the island), and although it doesn not directly influence the past physically…Charles remembers it in his nightmares that he tells Ben about.
Charles now has information that is vital to his returning…Locke is MIB/MIB is Locke, Des off island and able to be found, Penny and Charlie to be used as motivation for Des to do what he says, and of course ‘Team Widmore’ has successfully returned to the island. Desmond can now be used to give Charles the ability to return to the island simply by following his orders and flashing back to another time period.
Since he cannot physically travel as far as we know, I imagine by bringing him to the island and utilizing its properties it may enhance/evolve his abilities…and will most likely kill him…as much as someone can be killed on Lost. I think this may be hinted at before it occurs by us, the viewers possibly seeing Desmond reading/finishing “Our Mutual Friend” at some point soon…most likely the off island timeline.
Upon dying, he would be able to physically move through time, most likely creating a “Time Travelers Wife” type scenario between he and Penny. With this ability, he may be able to right some wrongs by doing something very similar to that which he does for Widmore, but for someone else…Locke…MIB…Jacob…?
Jack seems like the right ‘candidate’ being he has already been visited by Des on the non-crashing 815. I believe that he pays him a visit in the stadium from another timeline as well. Jack is important and Desmond knows it…Im just hoping that his ability is what I think it is…otherwise I have no clue as to what his purpose is.