at first, i did not like last nights episode, but it has really grown on me upon rewatching it a few times. heres a theory i have in regards to how mib became smokey. When jacob sent him into the light, the light acted like a magnet not only for metals, but for the light that resides in every human being. it in essence sucked the soul out of MIB separating him from his body, all the good in him was absorbed into the light and all that was left was evil which is manifested by the black smoke. dogen saying that mib was evil incarnate would make sense under this theory.
some other thoughts:
the mother obviously had supernatural powers, she was able to grant long life to jacob and mib as well prevent them from killing each other. its certainly not a stretch to assume she killed the people in the villlage and filled up the well.
Jacob is somewhat of a reformed in regards to how his mother did things as guardian. His mother was perhaps overly cynical of humanity where as jacob has a more optimistic view, and where she kind of scoffed at the notion of free will jacob seems to champion in it in the way he does things by giving people a choice to follow him or reject him.
another wild theory i have is that upon entering the light, the light and mib merged and that is why he cannot leave, because if he left the light would go out, and it also would explain how locke saw the light when he looked into the monster.
