I don't know why everyone hates Snow for leaving Serah back in 003 AF, there are so many possibilities the mind positively boggles, let me start off with a few of them: (SPOILER)First off, you call him lamey pants for doing something for his Fiancé in going to look for her sister who is obviously important to her, he said he had a vision himself, maybe he saw what would happen had he not left to go looking for Light and that he was fighting to save the world, now an ordinary guy has no chance of being able to take on all the mobs of the world out there without a little power boost, l'Cie is the only way he knows about, and its not like he has Serah's innate magical ability, if he wants to fight to protect the people he loves he needs to be the best he can be and so he turns himself into a l'Cie (which will no doubt be explained how he did this in future DLC) as to how several people got carted about in history (Sazh and his boy, and hundreds of other people throughout the game) have you guys not been paying attention to the major plot device that is the paradox system? who is to say that Sazh, Snow, Dajh and all the buttloads of other people throughout the game have not been swallowed up in a paradox and taken into the future, maybe in future dlc there will be a way for Noel to travel through time and hand pick people and bring them into the future of his choice... say Academy 500 AF? after all it is called Final Fantasy.

As to the whole, "y u no write me" from Serah's PoV, he got carted into the future... now I know Mog Mail is supposedly awesome, but I doubt they can send letters from the future into the past