That's my favorite theory, bawdy.

In trying to figure out what's gonna happen in the next episode, I thought I'd start with the spoiler that it's a female "regular" who offs another female "regular". Well, we know the decedent, so that's half the battle.

As for whodunit, we need to pull in Kristen's other spoiler about it being shocking to the point that she wanted to cry. The way I read that, it's more how she dies than who kills her that brings about such a visceral response, but in doing the deed, the perpetrator is revealed to be a potential "monster". So, based on the criteria that the killer must be a regular, must be capable of a shocking type of violence, AND must be headed down the trail of monster-dom, let's go through our options...

And the nominees are:

Sun: Regular? Yes. Capable of shocking violence? Doubt it. Likely to have story arc take a turn for the purely E-Vil? Nope. Verdict: Least likely killer.

Libby: Regular? Qualified yes. (She's in the opening credits and cast photos for Season 2) Capable of shocking violence? Not on a bet. This gal seems scared of her own shadow. Likely to have story arc take a turn for the purely E-Vil? Nah, she's more likely to come along and eff with everyone's head. Verdict: She's got bigger fish to fry.

Claire: Regular? Supposedly, but has been MIA this season. Capable of shocking violence? Maybe, if someone was threatening her baby or if she got programmed like some island Manchurian Candidate by the Others. Likely to have story arc take a turn for the purely E-Vil? I don't think so. She's been in all of 3 or 4 scenes this season, and in each case it's been in a supporting fashion. They haven't touched her story at all this season, and I don't think that's where it's headed. I think it's going to be more toward finally trusting Charlie only to have him relapse (or come close to relapse). I seriously doubt they're going to go Zero to Psycho Killer with her in the next episode. Verdict: Possible, but not likely.

Rousseau: Regular? No. She's not in any promo photos, nor is she part of the opening credits. Capable of shocking violence? Violence? Yes. Shocking violence? Only if the actions of a woman who has been trapped on an island for 16 years, has had her own infant ripped from her, has stolen another's baby to ransom her own, and has tortured a man with electrodes are a shock to anyone at this point. Likely to have story arc take a turn for the purely E-Vil? No. She's likely to remain the island's home-grown enigma. She has much more narrative value that way. Verdict: Doesn't really fulfill much of the criteria, so I say not the killer.

Kate: Regular? Yep. Capable of shocking violence? Yep. Even though we've seen her kill already, she still has this mystery around her that she may have done it all for defensible reasons. And she still has that innocent look about her. Likely to have story arc take a turn for the purely E-Vil? I don't think so. I don't think this is the right time for her story to take a nosedive into the black pit of heinousness. She's pining for Sawyer fer chrissakes. (Unless, of course, that was all an act.) Verdict: She's my choice #2, but I'd be shocked if it was her (which may, after all, be the entire point of this exercise).

Ana Lucia: Regular? Well, she's had a lot of face time the past few episodes and is one of the "new" cast members, so yeah, I think she qualifies as a regular. Capable of shocking violence? Definitely. I don't think we've seen half of what she's capable of. Likely to have story arc take a turn for the purely E-Vil? The best candidate, I believe. Her whole storyline, and the storyline of the tailies and what happened to them has led up to this moment. At this point she's like a female Sawyer--just a badass. I don't believe the audience at large believes she's a bad person. I think they think she's been through some sh!t and has some trust issues...and who could blame her? When she turns out to be a real bad seed (whether she was pre-crash or whether she became one post-crash), it will shock the audience, especially if she dispenses with her victim in a cold-hearted manner. Verdict: Ding, ding, ding. We have a winner!

From a pure storytelling perspective, it's not Lost's style to have such a major change of character in one episode after we've been led to believe the opposite. Yes, they do reveal dark corners in people's pasts, and yes, they do have characters do the unexpected, but for some character to go from generally good camper to evil ruthless killer in one episode? I don't think so.

Look at it from another angle. Episode 3 introduced us to the other survivors, but primarily focused on the Hatch. Episode 4 split island time about evenly between Hurley and the raft party. Episode 5 focused primarily on the tailies and rafties feeling each other out. Episode 7 will focus exclusively on what happened to the tailies up until now. What's the missing episode? Episode 6, wherein we see Ana Lucia do something so dispicable we sit back and think "how in the hell could someone do that?" Then we find out in Episode 7, in true Lost fashion.

Ana Lucia is your killer. That's my story and I'm sticking to it...unless it's Kate, or Claire, or...

Fester
I knew all those hours trying to spoil Survivor would come in handy someday.