CharacterWatch - Jack:
I wanted to cheer for Jack last night: this is the first time he's stood up and said "NO, I WILL NOT PUT UP WITH YOUR BULLS**T, ISLAND" since he's returned. He took a bullet for Sayid here by refusing to accept Dogen's "medicine" pill and risking his own safety to discover the truth -- and that's the Jack I remember and love from Seasons 1 - 3. Season 4 Jack was unable to look reality in the face and doggedly pushed to get off Island no matter what ugly truths came to surface about their would-be-rescuers from the freighter. Season 5 Jack bitterly realized what a blinded jerkface Season 4 Jack had been and after a lot of drinking and pill-popping set off on a "wherever the wind blows me" faith-in-the-island-centered return. Since then he's been apathetic toward everything (including the wellbeing of his fellow survivors) except the Farday-given, destiny-fulfiling mission to blow up the future in 5.16 (The Incident). But something's changed in our doctor: I think Juliet's death has woken old Jack up again. And, no, he won't lose the component of faith he gained, but nor will he remain the wind-blown apathetic jerkface of yester-season. Welcome back, Jack!
CharacterWatch - Kate:
Kate seems to get a lot of flak from LOST fans. This is probably a combination of two things: Her story-arch often seems removed from the mythology elements of the show, and her flip-flopping of feelings between Jack and Sawyer drives anyone who prefers a single one of those pairings mad. And of course those people drive everyone else mad, so everyone else tires of hearing about the "Love Triangle" plot at all even though it only takes up a small amount of actual screen time in the scheme of the show. Yet other fans go on and on ceaselessly about how selfish she is. It's not that the other characters aren't selfish at times, too, mind you, it's just that they're far better at being "Super Cool" while doing it.
While Kate's far from my favorite character on the show, I DO enjoy her storyline quite a bit, and don't find it to be as much of a muddle as some who claim there's no rhyme or reason to why she'll favor Sawyer or Jack at any given moment. The answer to this is simple: she favors them both. She loves Jack for the ideals and heroism he embodies; She loves Sawyer because she identifies with him. She shies away from Jack at times because his ideals can be oppressive; and she shies away from Sawyer at times because she doesn't LIKE the part of herself he embodies - the selfish, born to run part. This dynamic is set up very clearly in 2.09 (What Kate Did) and she has followed it very consistantly ever since.
She constantly goes out of her way to "save" both of the men she loves - an action that never seems to be fully appreciated by either, frustrating her and sending her ping-ponging back and forth between them. Once the abandoned Aaron is dropped in her lap, however, she's given new purpose and refocuses her devotions from the guys to Aaron. But the Island beckons, and she soon realizes her motherood is a lie and devotes herself to rescuing Claire as presented in 5.11 (Whatever Happened, Happened). Sure her feelings for both Jack and Sawyer are still in play when she returns to the Island in Season 5 (such things never go away completely), but her ultimate goal has new definition and displays impressive heroism.
Which brings us to Season 6. She's the same Kate -- she's still "born to run," she's nice to Jack, and she once again tries to "save" Sawyer -- but she's also still focused on her central goal of rescuing Claire, and this weeks' outing was named "What Kate Does" for a reason. By episode's end, she made a decision -- a difficult one, and what felt like a very final one: she walked away from Sawyer. After a heartfelt cry for Juliet, for Sawyer, and - yes - for herself. There comes a moment in all impossible relationships (or potential relationships) when you realize that it's finally, truly, completely OVER. There can be no going back. The end of an era has arrived and what remains... is emptiness. Kate breaks down under that reality, but after letting it out, she fills up her canteen, puts her torch for Sawyer to rest, and sets out after Claire, accepting that, as Sawyer said at the dock, "Some people are meant to be alone." The rest of the season may prove me wrong, but I think this episode will prove to be a pretty important climax to Kate's "love triangle" and "attachment" character archs. Hopefully she can find redemption in helping Claire somehow.