In Across the Sea, MiB seems to be just a normal guy who wanted to learn more, and have a real life. When he turned into the smoke monster, he seemed to turn...evil. That doesn't really make any sense. I was thinking about this, and I thought that maybe MiB is a victim of "The Sickness", in a way. You can compare what happened to him to what happened to Claire. After remaining on the island for many years, wanting one thing (for Claire - Aaron, for MiB - to leave the island), he became so desperate that he would kill anyone in the way. However, Claire got a little more...crazy. What do ya'll think?