Great discussion in here. I have some thoughts as well that I'd like to add.

First, I enjoyed this episode. I noticed another big comparison in Flash: Sideways with Ethan and Claire. He wanted to dissuade her from more needle sticks and drugs, where on the Island, he was the one that wanted to give her the needle sticks and the drugs. This time, it was her free choice, on the Island, she didn't have free choice.

Ethan's interaction mirrored her interaction with him on the Island, so to speak.

I think that Dogan and the Temple Others are assuming that Sayid is "claimed" by the dark force....just as Claire was claimed by the dark force. But, is it the dark force that has claimed them? I think not.

There was an illness as we saw with Danielle's French team and husband. They were infected with the illness and became insane and went to murder each other - Danielle. But, Danielle defended herself and shot them all. Just as she said to Claire in Season 2, "if your baby is infected, I trust you will know what has to be done".

It's confusing, because I don't look at that as the same "illness" that the Others are vaccinating against, or Desmond and Ethan. I think they have been vaccinating against the possession that can occur. AS they are referring to what has happened with Sayid and with Claire. But, clearly they are assuming that Claire has been claimed. If Claire had been claimed than Rousseau must have been claimed as well. We know that the survivors of flight 815 considered Rousseau insane early on. But, I considered her one of the "good guys". I never thought she was insane, just a mother that lost her child.

When I think of it this way, perhaps the other members of the French Science team were claimed, infected by the dark force, where Danielle perhaps was claimed by the light force. Clearly, they were not infected in the same way.

I think that Jacob or the good force has claimed Sayid....just as perhaps Claire has been claimed....as perhaps CHRISTIAN was claimed by Jacob. We do NOT know who has claimed the body of Christian, just that he was dead and that he keeps reappearing. Claire was with Christian. The only time the ash circle was broken was when Ilana came to the cabin, not when Locke and company came and saw Claire and Christian there.

I also want to state some observations. Dogan said in this last episode that he came to the island just as everyone came to the island. I think Jacob indeed brings people to the Island, and we know there are conflicts that arise time and again because of it. Man in Black comments that it is always the same end, where Jacob notes, it never ends, it's just progress. I think it will end with the last round of Jacob recruits to the Island, our survivors. I do not think the "Others" are on the same side as the survivors of flight 815. I do think they will perservere to resolve the conflict one way or the other for the Island.