So many things are now so obvious. All the people Hurley was seeing- Ana Lucia, Charlie, Libby, etc after they died, were obviously this enemy of Jacob posting as them, its been made pretty clear now a few times that dead is dead, so it must have been this enemy. But why, would he be desperate for them to go back, to the point where he would pose as several people to make them? Cause as well, Ben wanted them to go back too, so did he have something, like maybe an arrangement with this enemy? This is one bit I don't get and confuses the hell out of me.
And why is he so desperate to kill Jacob? It is quite interesting, and very deep and religious if you think about it. In the Bible, Jacob had a brother whom he has a bad relationship with, and I'm sure that he couldn't kill him himself and had to manipulate people into doing it for him, like the enemy did with Ben. Jacob will not kill the enemy, and the enemy cannot kill Jacob because to do so would be to kill himself in some way.
Another interesting point- Locke always had this thing, black and white, good and evil, ying and yang, remember backgammon thing as well. And if you notice at the start of the finale Jacob is wearing white, and the enemy is in black. And another thing that Will pointed out to me, a nightmare that Claire had back in season one, and pointed this out on Locke-
http://gallery.lost-media.com/displayimage.php?pid=27780&fullsize=1 I DO remember seeing that but totally forgot about it, didn't think much of it at the time but now, looking back at it its really interesting.
Quite interesting also, is how the enemy has all of Lockes memories. Makes me wonder, how? Has he been watching Locke and maybe the other survivors off the island, before they were on it and after they left it? Similar to how Jacob did it, but keeping out of the way maybe? Or does he just "get" them when he took his form?
I wonder though, how he [if it is human of course] can take form of people? Part me of me thinks as well, that this guy is the smoke monster, funny how when Ben saw "Alex" she appeared right after he saw it. Leads me to really believe its the same thing, maybe if they're not the same thing, Smokey is some kind of guard dog at least.