So i'm one of the people who believes that we have seen Nemesis as someone OTHER than MIB and Locke, i also believe we've seen him as Christian Shephard, Yemi, Robert, and probably a few other characters too. I believe that he's got his motives, and they mainly involve killing Jacob..
I'm also a fan of the idea that Jacob might be Aaron, only grown up... Now some people hate these kind of theories, and personally, i do too. But with Aaron, I think differently, because let's face it, Aaron is a character that we have all loved since the beginning, but yet at the same time, we know nothing about.. they've gotta do something with his character before the end, to make the audience think OMG !!!!!!!!!!!!!!!!!!!
So basically what i'm about to say is a bit of evidence that might support Aaron=Jacob.
When the french team come to the island, they are attacked by the Smoke Monster. I think it's aim was to kill the team, but particularly to kill Danielle, along with Alex. Danielle managed to escape, and got to the beach. She has managed to escape the smoke monster, because the monster is afraid of water...
Yes, i also believe that the monster is afraid of water. remember the tunnels, the plug hole, and the fact that we've never seen it cross rivers or go anywhere near beaches... plus it always seems particularly pissed off everytime it starts raining...
So because the Smoke Monster can't get to Danielle, Nemesis has a go, and dresses up as Robert. He fails, and Danile shoots him dead.
So once Daniele has the baby, Nemesis tells widmore to take the baby and kill it. So widmore sends ben, who decides not to kill it.
Now basically my point is, that Nemesis has tried bloody hard to get Alex out of the picture.. but why ? Why try so hard to kill Alex ?
Well, you remember the first ever episode Alex was in? Claire was remembering what had happened to her when The Others took her. And she remembers being in the medical station with Ethan, etc... Well they were gonna cut her open in order to save the baby, which i believe Juliet wanted, because most of the time the mum and the baby both end up dying anyway. However, just before the surgery, Alex helps Claire escape, and there fore saves both of their lives. Maybe if the surgery had gone ahead, then Aaron would also have died, along with claire. So maybe Nemesis wanted to kill Alex, because he knew that she would eventually end up saving Aaron/Jacob. Maybe Nemesis wanted to kill Alex because he thought that she would be the "loop-hole". Of course it isn't the loop-hole because let's face it that wouldn't be exciting enough. But i have another theory to what that loop-hole might be.. but that's for another post later on...
So what do you think lool ? Too Far-Fetched ? This whole Alex thing might be a bit too complicated and important for a characcter who died a couple of seasons ago. But oh well... leave a comment... don't be afraid to get agressive lol!