Born in Kyonin, Seth spent most of his childhood as a normal elven child, the son of a skilled craftsman, and had very little in the way of wants or worries. The closest he ever, or wanted to, get to action was joining his town's guard for a decade, picking up the basics of the blade. As he approached his first century, though, he began to wander from his home for a year or so at a time. During one of these wanderings, though, Seth was visiting the nation of Cheliax, interested in seeing the descent of Aroden as the god would arrive on Golarion. When that didn't happen, however, he was struck to his core by the sheer horror of those around him, and couldn't bring himself to turn a blind eye at the suffering and death as Cheliax fell from grace and the world collapsed around him. He turned and ran, fleeing from the fledgling authoritarian state's capitol to the country's outskirts. Unfortunately, he managed to find himself embroiled within the revolution as Galt declared independence, and was killed in the bloody revolt.
It was only in death, ironically, that Seth found his life's purpose. He doesn't remember exactly what happened while he was dead, but he does know that he and Pharasma had a conversation of sorts. She had need of him, though the reason or purpose to that was unclear, and had sent a young psychopomp to guide him into becoming Her sword. Over the last hundred years, Seth has been fruitlessly trying to end the Red Revolution and it's endless trail of bloodshed. It was only recently that he found himself sent in a new direction, though, and was told to make his way to Taldor, to use his skills to prevent the fall of yet another once-great nation into anarchy.