Alpert is allied with Linus. And further back to Jacob. He may have been the former leader of the Others.

Abbadon is allied with Widmore.

Both knew the importance of Locke before the crash.

It appears Widmore via Abbadon arranged for Locke to come to the island.

There was an obvious dichotomy between Alpert and Abaddon. Abaddon wanted Locke to embrace his Hunter side, by sending him on the walkabout. Abaddon (I believe) is representative of choice, and not being shackled to destiny or fate, Locke wanted to be a hunter, and that displeased Alpert, but in the end Abaddon showed him that there is always choice.

They are working on paralell paths, I believe. Trying to guide the "chosen" of the island to different outcomes.

Black and White stones, it's the backgammon game from Season 1. One white stone and one black stone in Locke's eyes, two sides vying for him.

There was an obvious dichotomy between Alpert and Abaddon.
I agree - this was one of the more intriguing points we saw tonight. Alpert's guru-advisor star fell a little, Abaddon's rose a little.

Black and White stones, it's the backgammon game from Season 1. One white stone and one black stone in Locke's eyes, two sides vying for him.[/quote]

I thought about the exact same scene when Albert and Abaddon were introduced this episode. I think you are right on the money about them being on opposite sides, vying for Locke's allegiance.