I personally think the new dragon rider will be someone already introduced but someone we wouldn't expect, that means not Roran. And Eragon, I agree that he will most likely not be the main character as usual. I figure he will be out doing something different making occasional appearances. I figure Eragon will have to go away, but maybe he gets injured again, who knows(except Paolini.) And as for Arya and Eragon, I say it's probably going to be like a lot of stories and she deny him til the very end then something will happen and they kiss and go skipping down the yellow brick road sort of thing. Sapphira, she will probably mate with the new dragon, which I predict will be to a good guy, and will have an egg at the end. This egg will be the start of a new series of dragon rider books(this is just my prediction.) If there is a new main character, and I mean like one who takes Eragon's place, then the story will be on a different path then the last three books, but good all the same. In the end, I think Eragon and Galbatorix will fight and somehow Eragon will kill him. I think they will also rescue the dragon orbs, and finally set the dragon's free. As for Glaedr, my friends and I have predict that the new dragon rider will be trained by Eragon, but the dragon will be trained by Sapphira, with the aid of Glaedr. What happens to Thron and, forgive me, I forgot his name, my friend is borrowing the book and I'm going off my memory, but as I was saying, Thorn's rider, good outcome, will probably be killed or turned back to the Varden by somehow breaking the magical bonds, or, bad outcome, he gets killed. As for Thorn, he will be either saved from the evilness, with or without a rider, or, killed along with the rider. There is one more outcome I can think of, Thorn breaks away from his rider and breeds with Sapphira, which is highly unlikely.
I have more predictions, but I have wrote a lot and want comments on this first.
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