FrighteninLilMonster, I'm going to disagree with you here, but it's not just you. A lot of folks share your opinion, a lot more than share mine, so I guess I'm trying to provide Sam's day in court, so to speak. Sam is not an easy character to like - with the exception of his kindness to Emily, we see him as remote, and occasionally heartless in his leadership of the pack. I suppose I see Sam as being selfless and responsible when he manifests the strength it takes to lead the pack, while Jacob doesn't want to do so. I see Sam as being protective when he tries to protect Bella against an unpredictable Jacob, Victoria, and the Cullens, especially Edward, who he has seen really hurt Bella before. These are qualities we as readers generally love in Edward - why is it so hard to see them as worthy in Sam?
When it came to the leadership show-down with Jacob, well, that was going to happen sooner or later. If you know anything about pack dynamics, it's clear to see that Jacob has been challenging Sam's authority practically from the beginning. Who else in the pack disobeys orders like Jacob? Who turns into a human so the pack won't know what he's up to until it's too late to stop him. No one else. And yet Jacob does it again and again. Sam was going to have to fight this out with Jacob eventually, and it comes to a head when Sam makes a really bad decision. If the show-down had happened when Jacob had wanted to run off to kill the Cullens, and Sam had physically stopped Jacob from doing so using an Alpha command, would the reader reaction been the same? I'm not certain.
I completely agree with you that his emotional manipulation of Leah was completely uncalled for. It was completely unforgivable, especially given circumstances with Leah and Emily. If he hadn't been such a good guy the rest of the series - well, I wouldn't be able to see past that at all. I suppose, as I have forgiven Edward for his big mistake, I generally tend to forgive Sam for his big mistake as well. Forgive, but not forget, of course.
Sorry to be so contrary! -Ariadnee