There is no Man in Black in the Alternative Timeline by Drieakko

A main characteristic in the alternative ATL timeline (ATL) is that none of the candidates of the original timeline seem to have been visited by Jacob. None of them ended on the island, and the island itself has been sunk. There has been no need for candidates.

To explain this, we can assume that none of them is a candidate in the ATL. One reason for that can be that there is no island any more. However, in the opening episode of season 6 we saw that the island had existed at least until the late 1970s. In the original timeline, Sawyer and Kate were visited before that by Jacob, but that does not seem to have been the case in the ATL.

So, it seems that Jacob did not have any need for candidates even before the island sunk.

Also, there seems to exist a new version of young Jacob appearing in the original timeline island. Appearances started in season 6. This Jacob-looking boy running in the jungle feels a totally different character than the passive, gentle and emotionally shaky Jacob we have so far come to know. It appears as if he possesses the characteristics of both Jacob and the Man in Black. Let us assume that this is actually the case - this young Jacob is a boy who was supposed to be born instead of the twins. So, this might mean that in the universe he is coming, there is no Man in Black.

This can now be concluded to a theory. None of the candidates in the alternate timeline are candidates, because there is no Man in Black. There has just been Jacob, as the MIB was never born. None of the candidates in the original timeline are candidates in the ATL, as they are not needed in Jacob's and MIB's game - since there is only Jacob, and the MIB never existed.

So, this would mean the timelines were split already 23 AD when the MIB was born. Only one boy was supposed to be born to continue the work of the Mother, but something intervened and the characteristics of the Island's Protector were divided between two individuals.

This would then mean that when Juliet detonated the bomb, the ATL was not created, as it already existed. Instead, a window between the timelines was opened. Perhaps the other young Jacob is using the window to appear in the original timeline, as his appearances started right after the bomb exploded.

If this is the case, the next question is, why does this ATL Jacob interfere in the original timeline?

Maybe his target is to course correct the split and negate the entire original timeline which was never supposed to exist. The MIB leaving the island would make that impossible, so Jacob works now the best he can to prevent that and prepare for the final showdown when it all "ends only once".