Locke was the "walking" definition of pessimism, a tendency to see the worst aspect of things or believe that the worst will happen; a lack of hope or confidence in the future.
In philosophy, it is a belief that this world is as bad as it could be or that evil will ultimately prevail over good.
His life went from bad, to worst, to crippling bad, to really bad to sadly dead. Whether Locke was intentionally written as a punching bag character, we saw him get beat up over and over again. His life started as being abandoned by his parents. His mother was crazy, and his missing father was a rogue con man. He grew up bouncing from foster home to foster home. He had no family. He built up bitterness. He wanted to be something he was not (like a jock when he was a good student). He turned away from science, something he may have been good at, to the self-imposed exile of dead end jobs. Misery was his only companion for most of his early adulthood. He tried to find a purpose and new family like the time he joined a commune. But as often happened, Locke was played for the fool. The family was a band of drug dealers; and his position in the group was to turn to snitch. Locke was often confused by his naive take on people; he trusted others too much that he constantly got burned. Nothing more tragic than reconnecting with his father. But that turned Locke into just another sucker - - - costing him first his kidney, and then his ability to walk when he was shoved out of a skyscraper window. Now, both a physical and emotional cripple, Locke's last hope for personal success and achievement was to go on his Outback journey. But that was halted before it began. He looked stupid and weak.
And what happens to stupid and weak people? They get played for fools.
Locke had his chance to re-invent himself after the plane crash. The miracle that he could now walk meant that his dream of being an outback hunter could come true. He relished the opportunity to be the big boar hunter. He thought people would have to respect his skills and his leadership. But in reality, the rest of the survivors were taken back by his aggressiveness to the point of fear. Only Walt wanted to hang around Locke (even though Michael told Walt not to do so.) In short order, Locke's real personality began to surface and he started to retreat from the group because they had chosen Jack as their leader.
Just as before, Locke went off on a personal quest just like with the commune. He was manipulated by the island's wild charms, the mystery of the Hatch, the manipulation by Ben and Jacob, and then seized by the smoke monster. Locke came out on the wrong end of each encounter. His stubborn position led to the Hatch explosion when the Numbers were not entered in time. His stupidity in playing a computer game led to the communications station to explode.
He was shot, beat up, time skipped, ripped away from the island by the FDW turn, re-crippled, and dismissed by all the O6 members in his quest to have everyone return to the island to "meet their destiny." Locke could never explain what that destiny meant, to the others or even to himself. Even when he was at his lowest moment, in a seedy LA hotel room ready to end his life, Ben extracted the last bit of information from him - - - then murdered him in a staged suicide. The world would then view Locke's life as meaningless, sad end.
Why Locke's body had to return to the island was not explained. It just added to the humiliation. For the smoke monster already had the skills to shape shift so it did not need Locke's dead body to become Flocke. Smokey used Locke's appearance to manipulate the candidates in order to turn into evil minions. The only impression Locke's death made was on Jack, who finally realized that Locke may have been right about the island. But, like a virus, this notion infected Jack and turned the rest of his life into one like Locke's: meaningless with a sad ending.
But there was nothing worse to kick a down Locke more than the actual finale. He shows up at the after life church, alone. He sits alone in the front pew across from Jack. Why is Locke alone? There was no one in his life that he could share the moment? What about Helen, who predeceased him after their break-up fight? She was his companion in the sideways world so why was she not at the church? Was she a figment of Locke's fantasy mind? What about his mother? Was her abandonment of him as a child so great that he had no bonds with her? So it was very odd that Locke was the only person in the church without a family relation or partner.
So why was Locke then even present at the church? None of the main characters such as Jack, Sawyer, Sayid, Kate, Rose or Bernard, felt any close connection with Locke. In fact, most of them turned their back on him. Many of Locke's decisions and actions caused them great pain, grief and sorrow. Locke looked out of place in the church because he was out of place. Everyone else in the sideways world had found happiness, but not Locke. It seems that the show dumped on Locke one last time in the final episode.
