K, first off, i'd like to say that most of this, if not all of this is NOT my original theory, its just kind of strung together by other ideas that other people on this site came up with. I apologise for the fact that i can't credit each of these in particular, or tell you their names. It's not that i'm inconsiderate, it's simply that i'm just that lazy. But thank you for those of you who put the idea into my head. :)
Charles Widmore was the leader of the Others, along with Eloise... They were also lovers. And then Eloise gets pregnant, which at first is a good thing, obviously.
Then in 1977, Daniel comes along and gets him shot (dumbass). With the journal, and the knowledge she killed her own son, Eloise completely changes her views on what she must do in life. She realises that instead of doing whatever the Others are doing, she must make sure time ends up the way it does, and she does this because the incident is somewhat necessary. Then, Juliet destroys the bomb, which makes pregnancy an issue on the island (which ironically is what she was trying to fix). Eloise realises that in order for her and the baby to survive, they need to leave the island. (Hence why she is not on the island anymore). From then on, she dedicates her life to making sure everything goes the way it does.
So charles is kind of pissed off now, because Eloise completely ignores him from now on :( very upsetting. PLUS, as if things couldn't get any worse, Dharma raid their camp (after finding out their position from sawyer in the interogation room), and kill a lot of the others. A lot ! So now widmore thinks, fine.. sod this.
So he confronts the Dharma, and becomes a spy (double agent) for them, just like Ben becomes a double agent for the others. In return, Dharma give him money. So Ben gives information to the others about dharma, and charles gives informaiton about the others to dharma initiative, and this keeps up the truce. However, after several years, the others decide to get rid of dharma, and they do. But then once they've done that, they find something in Horace's house, that proves Charles is a douchebag, which is when they send him off the island. Make sense ?
Well, that's pretty much all i have to say. What do you think ? And i know that there isn't much proof of all this, but it kind of does make sense. Plus, if there was a connection between charles and ben, this would kind of make sense right ??