It looks like Ana-Lucia agrees with Libby and Goodwin (Eko presumably not offering his opinion), but she's probably thrilled that she gets to lead one of her Bataan death marches through the jungle. They come across a stream, so she lets everyone break for five minutes. "We've been walking for three days straight, Ana," complains Bernard, who looks like he's already lost thirty pounds. "And you're still here. Five minutes," says Ana-Lucia, in some nice post hoc, ergo propter hoc fallacious reasoning. But Nathan has other ideas: "You want to keep walking? Go ahead. Fresh water, rock wall at our back, lots of fruit trees -- right here looks pretty good to me." He unshoulders his pack, and he and Ana-Lucia look at each other, with the rest of them looking at her to see what her reaction will be, before she finally says, "Fine, okay. This'll work," the way you might pretend to give permission to someone who's already made up his own mind.
Day 17. Ana-Lucia is hard at work digging a giant hole in the ground. Hiding place? Boar trap? Wine cellar? Close, but you're way off. Libby comes in and asks about what Ana-Lucia said about Nathan being gone for two hours. "He creeps me out, Ana. Do you really think it's possible that one of us is...one of them?" Ana pauses a moment. "Why do you think I'm digging this hole?" she says. Your own personal Lord of the Flies/Apocalypse Now descent into madness? But that's just a theory.
Day 19. Bernard and Nathan are setting up a little string and stick trap thing that's supposed to catch rabbits. Bernard seems unsure, but Nathan's confident -- at least, he is until Ana-Lucia walks in and kicks him in the jaw. Now he's just unconscious. Bernard's all, Ana! Holy shit!
So Ana-Lucia dumps Nathan into the hole, which by now is the fully realized POW pit once occupied (well, I guess that should be will be occupied) by Michael, Jin, and Sawyer. Nathan coughs and comes to, and understandably wants to know what's going on. "You and I are going to have a little talk, Nathan," she says. All this, because dude likes to take a long, reflective crap. He demands that she let him out, and she just responds by covering the pit. Ignoring his protests of innocence, she tells the other Lostaways that Nathan wasn't on the plane: "We were in the air for two hours. I didn't see him once. Not once." Well, I'm convinced. I can't believe she's serious with this shit. Goodwin points out that it was a big plane, but Cindy chimes in to say that she didn't see him either. "I'm pretty good with faces, you know, with the passengers, and I did not see him." Not to get ahead of myself here, but Cindy, mind taking a close look at Goodwin over there? Libby piles on too, saying that Nathan never talks about himself: "Every time I ask him anything, he just dodges." From what we've seen, this is true of Ana-Lucia too. Bernard wants to know, if Nathan really is one of them, why he's still here. "I don't know, but I'm going to find out," she says, and strolls over to where Eko is standing all silent and scary, holding his huge stick. "You got a problem with this?" she asks him. Like he's going to say out loud that he does.