[D-Roc]

This struck me whilst watching the episode and then taking a moment or two to think about it.

In their scene near the end of the show, Widmore told Ben that the island was 'his' and that Ben stole it from him. I believe that this is canon - certainly in Widmore's mind. I think that Widmore and Ben both instigated the Dharma purge. Charles Widmore had invested in the island - we know this from previous seasons of Lost, and his 'products' being in the food-drops.

Could it be that Charles Widmore wanted to topple Dharma - the people who allowed him to invest financially in their sciences, but didn't allow him a close enough affiliation with the island? We already know (some of) Ben's involvement in purging Dharma, we know that he had to be "patient", and we know that the 'hostiles' and possibly Jacob was involved.

However, could it be that this was a dual-sided purge? Ben/the Others and Widmore together planning and seeing through the purge of Dharma? Perhaps Ben's people dealt mostly with the on-island purge, and Widmore dealt with the off-island purge - since i assume Dharma had off-island people...

Did Ben and Widmore take an oath..perhaps establishing "rules" that they swore never to break even if they became rivals? Did Ben break this oath - possibly this is what Charles meant when he told Ben - "I know WHAT you are" - was he referring to Ben being a 'cheater' for double-crossing him, and taking the island - something Widmore believed was mostly his - for himself?