Entrail_JI
So original Ren may not be who we think he is. He seems to want to take control of the situation in the novel. Direct it in a manner he deems correct, and some version of Kevin is trying to alter the course of his world's history. Which is what led to the author reincarnating into the world of his novel as Ren Dover. Still a lot of questions and not enough answers.
So we can now assume that this "original" version on "Ren" is the time remnant that Kevin keeps getting notified of. Kevin's assumption of our mc Ren might actually be correct, "that what would he know?" Besides piecing this together, I am completely lost. What I had thought to be a predictable, linear story, has now spiraled out of comprehension...and I love it.
Theory time: Ren is most likely not the demon lord. Instead, our Ren is being manipulated by a past Ren for the “origin of all magic” thing. A past Kevin must have protected it, like always, but ended up failing. So past Ren is in this never ending cycle of trying to get Kevin to beat the demon lord for some reason. Why our Ren is being manipulated, restrictions… probably; why the demon lord is important, direcrly related to something. Everything is still up in the air.