So far I am at Augusta Tower. The story is revolved around the Chaos Theory and Butterfly Effect (http://en.wikipedia.org/wiki/Chaos_theory
). This mean that a change in your initial condition will cause a chaotic effect in the future. If there no change in a initial condition then there will be no effect. How does this relate to FF XIII-2?
FF XIII was the initial condition. For ages there were just Pulse and Cocoon ruled and ORDERED by the Fal'Cie. 'Order' is a key word because each Fal'Cie had a responsibility, which keep things in order on both Pulse and Cocoon. When the team defeated Orphan and saved Cocoon (supposedly save, which I still don't think they really did) it changed the initial condition condition of FF XIII, which was the order created by the Fal'Cie. With order there is no chaos. Meaning everything is a linear
effect (even the game itself is linear)
. The Fal'Cie had already determined the fate of mankind. With that order destroyed -the butterfly effect is now chaotic. The future has changed.
So now we are at FF XIII-2. There is no order. Everything is chaotic and non-linear (obviously with all the time traveling back and forth through the future and past). The game start with Ciaus and Lightning in an intense battle. Clearly Ciaus want to destroy everything, which was the original fate of mankind. With the ability of time travel now there have been so many paradox created that has cause distortion in just about every time period. Noel is the contradiction that Ciaus has been talking about. Noel is part of reason that everything is now chaotic. Ciaus just want to finish what Orphan didn't do. If Noel would have just died in his time, then butterfly effect would have been completed. But he didn't! He met lightning who was apart of disrupting the butterfly effect originally.
Ciaus is trying to stop Sereh and Noel so he everything will die, but as long as they live the future continues to change and mankind will continue to thrive.