We know that Nina Dobrev, a.k.a. Elena Gilbert, will return to the CW's melodramatic playground of the undead for one final visit. We know that when she left, Elena's life remained tied to Kat Graham's Bonnie; as long as Bonnie lives, Elena remains asleep. Could Bonnie's death explain Elena's sudden reappearance? Or will Paul Wesley's Stefan, who recently transitioned from vampire back to human, attempt to make up for turning his brother Damon (Ian Somerhalder) all those years ago by sacrificing himself to allow Damon and Elena to spend eternity together? Or will poor Zach Roerig's Matt Donovan, the show's only main character to remain human throughout its entire run, die once more — this time, sans resurrection?