Why They Will Win
It was the night before Carthage and the house was eerily quiet. Dean couldn't sleep. He was laying on the top of the Impala contemplating how they had gotten this far, and the big weight of what they still had to do the next day. Yes they had the colt but how are they actually going to kill the devil. This is Lucifer the God of the Demon's. He is the nightmares of little children. The fallen angel that is seeped in sin, that fell to earth because he would not bow to humanity. One of Gods favorite that was cast out of Haven by Michael the archangel. He is the devil of the Bible. The Ultimate evil. Nothing that they have done compares to what is in store.
He remembers growing up without faith not believing in any God or Devil. All he knew was hate and pain and violence. Dean only believed in what he could see, and he saw evil every where. Following his family since the very beginning. He saw it in everything. He saw it in himself and that was the worst. He knew what he had become while in hell. He would change it if he could but there is not going back no turning back time.
There have been few instances when Dean would see the good in humanity mixed with the chaos of the world. His first kiss ,the first time he had sex, smile on Sammy's face when they were young. Little moments being a family that is all he ever wanted. Dean knows love the fierce love of family and he holds that close to his heart every time he thinks of giving up, and that is why they will win.