I was beginning to worry that the writers would not reveal all aspects of "the rules," with such little time available. However, I had the revelation that this list of rules I've been imagining is not long and complex with many many stipulations. Perhaps they are more general; my thinkin was that the "loopholes" that MiB is tryin to find in order to get the candidates to kill each other are dodging the same rules as the loophole to kill Jacob. It seems obvious to me now that Jacob is merely in the same standing as candidates (cannot kill himself or be killed by MiB directly), and isolated himself from everyone on the island as the last, fail-safe keeper of the "cork". He never came close to humans so that MiB would never have a chance to manipulate a pawn into killing him with ease. That's why finding this loophole was so difficult... MiB was having trouble finding someone to manipulate that was high enough on the foodchain to gain an audience w/ Jacob. I just hope to gain a little more knowledge of the rules with respects to why Ben couldn't kill Widmore while they spoke in Widmore's bedroom. Is there something that I am missing concerning the rules? I do believe Jacob arrived on the island and was recruited in the same way by (an alleged) former protector. I believe he was at one time in the shoes of Jack and the rest, which is where the next candidate will end up.