One of the things that annoys me most is that the charactors' motivations seem to turn on a dime. Ben, for several years, has been the evil leader incarnate, and then, suddenly, he turns all sheepish and is willing to do whatever John Locke (who Ben killed — uh — twice) says. Why the change? Well, he explained it in a ten second conversation with somebody at some point, but it just didn't hang together.
Kate boards the submarine to convince Sawyer and Juliette that they need to stop Jack from denotating an atomic bomb that will destroy the island. Juliette, who has been hellbent to get off the island up until now and begin her life with Sawyer, suddenly agrees with Kate. Why the change? Oh, she gave some ten second explanation, but it really didn't make sense.
But the "turn on a dime" phenomenon gets worse….
So Kate, Juliette and Sawyer commandeer the submarine, force it to the surface, get in a lifeboat, and go to the island. They finally confront Jack in the jungle, on his way to the Dharma construction site where he intends to detonate the atomic bomb. [Footnote: it's not clear why he has to go to center of the Dharma construction site — it seems to me that he could detonate the bomb NEAR the site and it would do the trick. It's a friggin' A-bomb, after all]
And after all that — after ALL that — Kate decides to help Jack in his quest, and so does Juliette. And why the sudden change? Why did they decide to help Jack after coming all that way to stop Jack?
Well, I don't even remember Kate's ten-second explanation. She just changed her mind though, all right? We're just supposed to accept it.
And Juliette decided to assist, rather than stop, Jack because — well, according to Juliette, she saw how Sawyer was looking at Kate, and began to doubt that she and Sawyer were supposed to be together. Therefore, she's going to help Jack detonate the atomic bomb so that none of this time travel stuff will happen.
I pity these actors who have to play within these wishy-washy charactors. They spend episode-after-episode in which their character seeks goal X, only to be handed a script where their charactor does a 180, and decides on a different course. And about 5 seconds of dialogue to explain the sudden change in motivation.
That said, Michael Emerson really is a good actor.