Locke takes off his Rambo-sized knife and throws it to the side. "We didn't come here to hurt you," says Locke. Good thing, Locke, since Desmond's got the drop on you. Desmond wants to know why they did come here then, and Kate helpfully says that they were in a plane crash. Since that really doesn't answer Desmond's question, he says "Were you now," and asks when that was, and Locke says, "Forty-four days ago," and Desmond repeats this and thinks about it for a moment. Notice also that Desmond has a Dharma logo on his jacket.
Then he circles around them, still training the rifle on them, and he orders them to move. They pass by a wall covered with counting notches, four vertical strokes with a diagonal. Likely days he's been here, or solo ping-pong victories. Locke asks how long Desmond's been here. "Shut it!" That's how long!
Next to a door, Desmond tosses some rope to Kate and orders her to tie up Locke. She hesitates, and he yells, "Do it!" Locke tells Desmond that he's tying up the wrong person. "How's that, brothah," says Desmond, and Locke says he's not the dangerous one. Kate, on the other hand, is a fugitive, says Locke. Kate just stares at Locke in disbelief. Desmond considers this, then swings his rifle back to Locke. "So what does that make you then, brothah?" Locke says, "I'm a regional collections manager for a cardboard manufacturer. Boxes, primarily."
Now, Desmond may very well be crazy, but I don't think he's stupid. Locke was the one with the disemboweler of a knife strapped to him, not the five-foot ninety-pound woman next to him, but Desmond changes his mind and orders the "box man" to tie Kate up. He goes to do it, and Kate resists, getting the rifle shoved into her face some more. As Locke pushes her against the wall, she asks what the hell he's doing, and he whispers that he's doing what's best for all of them. With their backs to Desmond, Locke pulls something out of his pants and shoves it down the front of Kate's pants. Let's presume it was a little folding knife. Let's also hope Locke took a bath this morning before sticking his knife all down in his junk. Having finished his highly suspicious tying-up of Kate, Locke turns around, and Desmond has him shove her in a dark room, with her yelling and pleading, presumably for show.
We rewatch that scene where Jack gets ready to go after Locke and Kate, with Hurley reacting with disbelief. This time, though, we also see Jack stomp past Charlie and Claire and little Aaron. Claire asks what Charlie thinks that was all about. "I reckon Jack's going to do something heroic," he says, and Claire rolls her eyes at him, which I can't believe isn't the standard reaction whenever Charlie says anything anyway, and she complains that he always tries to be funny when he doesn't want to answer a question. To be fair to Charlie, I don't know that he doesn't want to answer that question so much as he doesn't actually know the answer to that question, but Claire can continue to be rude to the guy who's done quite a lot to help her out since they crashed if she wants. (Charlie takes offence to her qualifying it as him trying to be funny.)