With "Across The Sea" we had a lot of answers, instead of being given directly from characters in previous episodes, needed to be interpreted by ourselves. So I want to write something that would hopefully help with these answers.
We saw the birth of Jacob and MIB from early on, and to me that would indicate Aaron is definitely a candidate, same with Claire, with their Shepherd's bloodline. It would also perhaps explain the pregnancy issues on the island, perhaps trying to avoid another Jacob/MIB scenario? This was solved by science (medicine), however, I can’t remember the pregnancy in 1977 was helped by the medicine, perhaps it was the ankh that saved the baby?
There had been many mirror images that the writers had given us in reflection to Jacob/MIB’s actions – chasing a boar, MIB calling the light beautiful/Locke calling the smoke monster beautiful, MIB seeing his mother/Ben seeing his mother, Jacob attacking MIB/Jack attacking Ben in Season 3 Finale.
It was MIB’s idea to build the Frozen Donkey Wheel, hence be able to be teleported off the island rather than to be like Desmond being forced the push the button, the same thing that’s felt by their adopted mother. She loved them and hope they would not be corrupted by humans, but said “Thank you” to MIB for killing her.
What would happen if MIB do leave the island? Would he decide to wipe the entire human race out? I doubt it. Yes, he’s angry, but he’s not a heartless and emotionless person that we come to think.
And we come to perhaps the hardest answer to digest. How does the light turn MIB into the Smoke Monster? What is the light? I’d like to think of it as the origin of life, or something like the Sun, if this light goes out, all lights goes out. But it may also be Hell, and the island is the cork that keeps it where it is (like Jacob said), which effectively turns MIB into the God of Death, which I had long suspected/hoped for.