Here we finally get to the book’s main character, though I suspect that most readers won’t catch that he is the one until we’ve come back to him at time or two.
Discounting Shallan, who was not in Way of Kings Prime, Kaladin is the one who went through the biggest evolution over the years. Dalinar has been Dalinar from day one. Adolin, Jasnah, Renarin, and Taln all solidified into themselves while I was writing Prime. Even Sadeas (under a different name) is basically the same person now as he was ten years ago.
Kaladin, though… Well, I had some growing to do as a writer before I could write him. He started in my concepts as a very generic fantasy ‘farmboy’ protagonist. In Prime, there was nothing really original or interesting about him other than his situation. This is the danger for that style of protagonist; I feel that the best characters are interesting aside from their role.
For all my love of the Harry Potter books (and I do think they’re quite excellent), Harry is a blank slate at the start. He’s not interesting—the situations he’s in are interesting. It isn’t until later books, where he gets things to care about (like his godfather) that he starts to be defined as a character.
Kaladin was the same way. It’s odd how writers are sometimes better at giving personalities to their side characters than they are at giving them to their main characters.