This time I really think I’ve figured something out. Really. I mean it.
The Island has two particularly strange characteristics (among several others): babies can’t be born on it (with important exceptions) and dead people walk around on it. We know that one of those dead people, Locke, is actually Esau (Smokey). I’m willing to bet that all dead people we have seen walking around on the Island are in fact Smokey, including Christian, Claire, Boone, Harper, Ecko’s brother, etc… Smokey is death.
I’m also willing to bet that babies born on the Island, including Aaron and Alex, are somehow connected to Jacob or are Jacob. Jacob represents life.
In the conversation on the beach between Jacob and Esau in the final episode of last season, Esau says that it always ends the same way. I think he means that we all die. He repeats this theme when he tells Ben that only Locke understood how pitiful his life was — perhaps all life is. In Smokey’s view life is futile ending in death.
Jacob agrees that it always ends the same way (we all die) but there is progress. Jacob believes in the purposefulness of life.
Remember that Ben brings Juliet to the Island so that they can have babies, perhaps expanding Team Jacob. Widmore, on the other hand, wants to kill baby Alex and ultimately does through the mercenaries. Widmore is part of Team Esau.
Also, the dead Alex appears to Ben under the Temple scaring him into doing whatever Locke says, but Locke is actually Smokey at that point. Alex has to be dead so that Smokey can appear as her and trick Ben into following Locke’s orders to kill Jacob.
I don’t know what the “infected” people, Sayid, the new Claire, and Rousseau’s colleagues, really are. Perhaps they are being drawn into Team Esau. Remember that Rousseau’s colleagues went under the Temple, where Smokey attacked them, and Rousseau did not. Perhaps Smokey infects people there, maybe because they went into a spring like Sayid did.
We also know that Ben summoned Smokey to kill the mercenaries by draining a spring, again suggesting that Smokey and the spring are connected.
I don’t have it all figure out — not by a long stretch — but I’m pretty confident that this death/life theme will help tie the plot together.