I'm not entirely sure as I haven't read it recently, but usually King creates complex and diverse characters. It could be an ordinary person who gets caught up in extraordinary circumstances.
In 'Everything's Eventual King Short Story', there might be a protagonist who is on a journey of some sort. Maybe a young man or woman who is trying to make sense of a strange world. King often has characters that start out as relatable everymen or everywomen and then are thrust into situations that test their limits. There could also be some secondary characters like an old mentor figure or a mysterious stranger who either helps or hinders the main character's progress. Without reading it again, it's hard to be more specific, but King's characters are always interesting and multi - faceted.