Jon Snow is alive—or at least he is on television. In the Song of Ice and Fire books upon which the HBO show is based, Jon Snow remains dead. And while last night's episode of Game of Thrones suggests that Jon Snow will return to George R.R. Martin's books, Martin still reserves the right to change how exactly the character makes his comeback.
Martin, who left Jon Snow for dead in his last book way back in 2011, has said that many aspects of A Song of Ice and Fire will be different than the show—though they'll both reach the same general conclusion. It's a savvy business move: Why read on a page what you've already seen captured (more succinctly) on screen?
One of these diverging plot points could be Jon Snow's return. Jon's revival felt fairly anticlimactic on the show, which needs to move the plot along if the producers plan to finish in eight seasons. But book readers have been waiting years to find out how Jon Snow will rise again. Martin is likely to reward them with a lengthy explanation, and he's dropped plenty of hints that there are other ways besides Melisandre's magic to bring a person back to life.
The most popular theory is that Jon Snow warged into his direwolf Ghost before his death. In the novels, all the Stark children can warg—even if they don't know it. And in the books, Jon Snow whispers, "Ghost," just before he is stabbed for the final time. Many readers believe Jon's final words—not to mention Ghost's very name— foreshadow his warging. (For what it's worth, Jon did not say "Ghost" on the show.)
The epilogue in the book immediately following Jon's death follows a Warg who is trying to find a new host body. This may seem random, but the sequence becomes relevant if it is treated as context for Jon's return.
There's also the possibility that Jon could make a fiery comeback. A popular theory among fans suggests that Jon Snow might have Targaryen blood. (See the explanation of that so-called R+L=J theory here.) In the North, they burn all dead bodies to prevent them from becoming wights at the hands of the White Walkers. But we know that Dany, a Targaryan, entered a fire without being killed. Would burning Jon Snow's body revive him—or at least not damage his body, proving that he is a Targaryen?
The show still has to explain a lot about Jon Snow's resurrection: Did Ghost play a role? Was the sacrifice of Shireen a life-for-life trade to bring back Jon Snow? Why did the Red Woman try to seduce Jon last season, and will that factor in at all? If these questions remain unanswered, expect Martin—who is unwaveringly meticulous with his storylines—to address them in the pages of his future books.