Ben Linus, Master Manipulator Manipulated by Evelynne Weakley

OK, I think I've got my head around the whole Ben/Widmore/MiB/Jacob thing.

The way I see it is, Jacob is all about giving people chances to prove themselves. So when Kate and Sawyer turn up with the young Ben Linus, he sends Richard to accept him into the temple and be healed by the Pool of Life.

Ben is duly accepted into the Others, even if he still has to live in Dharmaville and follows Jacob.

By this time Ellie and Widmore are the leaders. They are aware of the whole Island/cork/evil/MiB/Candidates scenario, unlike Ben. Widmore is a Jacob loyalist, but is a general in a war. When Dharma's experiments threaten the Island and risk MiB escaping, he has no hesitation in ordering the Purge.

Meanwhile, MiB has been whispering in Ben's ear, realising that Mr Linus is far more easily manipulated than Widmore. Believing himself to be following Jacob, even though he is following his own ambitions, he is persuaded to have Charles and Ellie evicted from the Island and takes over the leadership of the Others. Widmore spends the next 30 years or so gathering his resources to return to the Island. Widmore and Ellie fall out over Widmore's willingness to use any and all means, even their son Daniel, to protect the Island.

I believe Widmore knows the identity of the candidates and also knows that Desmond is "special". He tried to keep him from his daughter, sent him on the yacht race leading to the Island. He also made sure Desmond had Penny's contact details so that he could reconnect with his Constant.

When the freighter arrives near the Island, Ben is terrified. He knows Widmore has come to reclaim the Island and does whatever he can keep the freighter away. He also doesn't care about keeping the Candidates on the Island unlike Widmore.

He continues to be self-serving but believing he is following Jacob until Alex's murder, at which point he consciously allies himself with MiB. He allows the Candidates to leave the Island and attempts to kill Locke. I think then he regrets swapping his allegiance and his one last good deed for Jacob is to turn the Frozen Donkey Wheel rather than Locke

Off Island he pursues his vendetta against Widmore by having Sayid kill off his associates. I believe he also is aware of Widmore's interest in the Candidates, even if he doesn't know why.

I believe then he comes into contact with Eloise Hawking, who reveals the entire truth of the Candidates/Island/evil/cork and the necessity of returning the Candidates to the Island. He returns himself to be judged, but not by MiB, by Jacob. However, MiB makes it clear Ben is now his slave and has him finally kill Jacob, something I believe he regrets deeply. I think his returning to Illana and Jacob's side is genuine now.