Jacob/MIB Roles by LOST@work

Jacob and the Man in Black are brothers, probably twins. Their mother (discussed by “Locke” in the most recent episode) either lived on the island already, or somehow was brought there. They may have been part of the ancient civilization that existed on the island. It’s possible that long ago, those born on the island were given special abilities by the island’s unique properties, and that people with certain powers may have some of this bloodline within them. (It would explain why the Others weren’t sure if Michael was really Walt’s father, and why they were running blood tests).

Anyway, Jacob and his brother each inherited different duties: Jacob’s job was to oversee the healing fountain and to watch over the island, and his brother was charged with overseeing the island’s security system (the black smoke), to more or less be the judge. Each of them was so wedded to the properties of the island that it gave them powers that would seem magical. At some point, the Man in Black was killed, by the knife that Dogen eventually gave to Sayid. The Man in Black’s soul remained on the island, trying to find a way to reincarnate. Since it was always his job to oversee the black smoke, the Man in Black knew he could use the smoke as a medium, a way to take a new form. To prevent this, his essence was imprisoned by Jacob in the cabin. The Man in Black could use the smoke to take other forms but never for a great length of time, as his essence could not leave his prison. But now he’s been freed, and has fully incarnated himself in Locke’s form, and he�€! ™s used the smoke to do so.

The sideways universe is a parallel reality, one of possibly many worlds. The island exists in all of these realities, holding together space and time by acting almost as a cornerstone. If it does not exist or is damaged, eventually the spacetime continuum would collapse, and the various universes would begin to bleed in to one another, creating a domino effect that would unravel reality. The sideways storyline will involve another effort to protect the island—which may be in danger since it’s already sunk beneath the ocean—and eventually this effort will somehow interact with the main timeline.