I created the above diagram to try to chart the main character's emotional path through the series.
On the left side, positive attributes which begin with basic hope, then move up to dreams, love, trust and leadership. On the right side, negative attributes with basic regret, then fears, hate, naivety, to being a follower. A stronger will comes with each level toward the bottom line of being either a leader or a follower (a theme of the series).
I started the chart by simple word association. I began with hope, then quickly worked up the emotional ladder. I then started on the right side with the opposite of hope which I thought would be regret, and then by quick word association got through the series to the opposite of leader.
On the light side, there is a fairly clear progression a person would take in a path to leadership. One would have to have some hope (which is tied to a goal). From that point, one would dream about that goal. One must love what they are after. Then they must trust themselves enough to succeed. And once that trust has been obtained, it can be projected upon others to form leadership.
Likewise, regrets can easily morph into fears. Fears can compound themselves into hate. Hate can cloud judgment to make a person outwardly naive. Being naive means people can take advantage of you. You become a follower.
In the light example, we can take Jack. Jack had hope as a young boy that he would someday impress his father. He dreamed that he would become as successful as this father. He loved medicine and his ability to help other people. His love of his craft led to other people, including patients, trusting his judgment. Such trust can him leadership skills in his OR teams. People looked to him to make the right clinical decisions. Those qualities made him a natural candidate to lead the survivors.
On the flip side, Locke had regrets from an early age. He regretted not having a normal family life as a child. Her feared that he would be unwanted as he was raised by successive foster homes. He began to hate how people perceived him. He hated that he was being directed to the uncool sciences when he wanted to be a popular athlete. His hate made him distrustful of other people. As a result, he bounced from meaningless job to meaningless job. He became withdrawn. He was then quite naive when his father reappeared in his life. So much so, that his kidney was stolen. Because he was so naive about the people around him, he could only be a follower throughout his life. And that realization is something that Locke attempted to rebel against, until he realized that no one would follow him. That dissolved any hope (and all those light side emotional states) of change. He died a bitter and broken man.
But both sides can stumble down a different path. Hope can turn into fears, which could become so strong as to consume one's psyche to love the paranoia and pain. That misguided love of pain can lead to naive isolation, which was the safety net Hurley had at Santa Rosa.
Likewise, regrets can turn into one's dreams. Unfulfilled dreams can quickly turn into hate. Hate can be marshaled into developing a trust with other people who do not factor in your dreams. That trust turns one into a follower, just as Sayid had become during his youth to Iraqi soldier days.
This chart also shows that change can make a difference. False hope can turn into hate, but that strong emotion can be channeled into great leadership qualities, as was the case with Ben and his ascension to leader of the Others.
Likewise, regrets can turn to love and that love can make you follow a special person instead of running away, which is an explanation for Kate becoming Jack's partner in the after life church at the end.