“BSD (Black Shirt Dude) is Rissa's abbreviation for the guy threatening to kill Jacob at the beginning of the episode. I'm a fan so I'll be adopting that name for the rest of my post. Clearly also he's the one who's been masquerading around as Locke. (Also Rissa figured that out like halfway through the episode. Rissa you are my hero).Anyway, Discussion topic number 1:I'm now operating under the assumption that BSD is actually the smoke monster .Evidence For: 1) The smoke monster is the only thing we've seen that can adopt the forms of other people.2) It's been interested in Locke from the very first season, and has definitely had major influences on the actions of both Locke and Ben. In fact, I'm now pretty sure BSD was posing as Christian, especially since the mercenaries with Locke's body said someone else had been using Jacob's cabin. And Christian has definietly been influincing Locke's actions as of late.3) It's a big cloud of black smoke, and they were really careful to juxtapose BSD with jacob wearing white, both at the beginning of the episode and at the end where Jacob is still wearing white and "Locke" is wearing black.Evidence Against:So the only flaw I've spotted in my theory is that "Locke" seemed surprised when Ben told him the smoke monster made him promise not to fuck with Locke. If BSD and the smoke monster were the same entity then he would already know that. But maybe he was just pretending to be surprised.Discussion Topic number 2:I think it was Rissa that mentioned this initially, but I think it's a cool idea so I'm gonna run with it. This dark guy/light guy juxtaposition combined with the fact that one of them wants to kill the other definitely calls to mind a God/Satan type relationship. One cannot exist without the other kind of thing. For a while now I've thought that the island was some sort of sentient being and that the smoke monster was its physical manifestation. This last episode has made me reconsider. I think clearly Jacob and BSD are entities (I'm not going to call them people because clearly they have magic powers or something) that are somehow connected to the island, but it's not clear exactly what this connection is. Maybe they are both manifestations of the island in a kind of split personality, angel/demon on opposite shoulders kind of way, but somehow I don't think so.As you might have noticed, I am waaaaay more interested in the BSD/Jacob story line than I am in the "lets change the future" story line. I love Miles even more because he finally brought up the "aren't you worried the bomb is what causes the accident?" question. But still quite excited for next season.”