Ok, so, I have this entire book series planned out, and I've written a rough outline for it. There is an issue in a certain area of the plot, however. It's a major event that affects a lot of things in the story. To explain my problem, I will have to explain a little bit of the event. Basically, there's this guy, his name is Cole. Cole is going into a machine in an attempt to recreate a history that doesn't exist. He is going back in time to relive the life of someone who technically doesn't exist in the period of time that Cole is in. Now, the problem I am having is figuring out what happens in the future, after Cole comes back out of the machine. How would recreating Ethan's life (the one Cole went back for) change what happens? I don't want to create a continoum where Cole is going back over and over. I also wanted to explain that Cole is going back because he needs to find "a key" in Ethan's past in order to fight a threat in the future.