Before tonight's episode, I'm going to theorize that Aaron grows up to be the man in black-smoke monster. Here's the set up:
1. Claire gets off the island and back to lil Aaron.
2. She's crazy, it affects Aaron and he spends life searching for this island of mysteries, miracles and magic. The island that made his mom go mad.
3. He finds the island, but it is empty. He eventually finds the gear that can shift the island in time and space (a mystery they have never explained like why time moves slower on the island).
4. He goes back in time too far and only Jacob is there.
5. Jacob figures out Aaron is angry and has a power triggered by his return to the island. He finds a way to keep him on the island without killing him. Aaron is left as a smoke monster who can take the form of dead people.
This explains why MIB never hurt Claire when she was on the island. It explains how MIB has taken care of Claire at all times. MIB forgave Claire for sneaking away from him and trying to leave him behind. Claire and Aaron were important to the Others and random people throughout the show. MIB told Kate that he had a crazy mother and it made things tough. What I find strange is that the MIB can't take another form anymore. John Locke is his last form and Ileana knew it, but how? Anyone cutting a deal with MIB should have asked this question: why would a being, who could promise me everything in the world, need an airplane to leave the island? I think in the end, the MIB-SMoke Monster is still just a man. A powerful being, but a man.
The island acts in strange ways, and what if the island was killing pregnant women because it knew a child born on the island would potentially be so evil? What if the island just didn't know the child was brought to the island late in the 3rd trimester and born there? Why would an island that can heal cancer and cure paralysis kill pregnant women? Something is wrong there. I think the island knows MIB was born on the island after a certain date and it tries to kill off that child that will grow up to be so angry and powerful. This entire show has been built on parent-child relationships, and what better way to solve a big mystery than to have the big bad smoke monster be the child most screwed up by what the island did to his or her parent.
LOST has many great mysteries that we will never learn the truth about because the creators couldn't pace the final season correctly. The MIB-Smoke Monster vs. Jacob mystery is one of the prime pillars of the show. Who or what are they and why is this all happening? I'm probably completely wrong as this is LOST, and the revelation will be way dumber. We'll see tonight, brutha.
***We'll forget all of the parentless kids created by the island like Walt, Sun-Jin's kid, potentially Desmond's boy Charlie.