Half the fun of Game of Thrones is untangling all the connecting threads and forming theories that might tie things back together in unexpected ways. Though some of these theories end up being rather far-fetched, others are much more plausible. One concerns the newest reveal about Red Priestess Melisandre, who took off her magic necklace at the end of the Season 6 premiere, "The Red Woman," and aged suddenly into the form of a very old woman. In the same episode, Cersei reminded viewers of a prophecy told to her by a witch when she was a child, and it seemed like there might be a connection considering both events occurred in the same episode. Is Melisandre the witch who delivered Cersei's prophecy?
The prophecy, given to Cersei by a witch called Maggy the Frog, has been weighing on her for a long time. It has haunted her since childhood because it foretells not only the deaths of Cersei's three children, but the death of Cersei herself. Going just off casting, Maggy and Melisandre are not the same person; Maggy was played by Jodhi May, and Melisandre is played by Carice van Houten. But if Mel can disguise herself to conceal her true age, then who's to say she can't make herself look like someone else? Arya is learning the art of exchanging faces, which means it's clearly something that's possible in Game of Thrones' world.
However, the theory begins to feel far-fetched pretty quickly. In A Feast for Crows, the book in which the prophecy first appeared, Maggy is described as looking appropriately frog-like but it's also explained that she had lived in Lannisport, not far from Cersei's childhood home of Casterly Rock, for many years. If Melisandre is as old as she appears, it wouldn't be impossible for her to have lived in Lannisport for a long time under an assumed appearance but it does seem like a little bit of a stretch. In a quote from the book, Maggy is described pretty unfavorably: "The old woman’s eyes were yellow, and crusted all about with something vile. In Lannisport it was said that she had been young and beautiful when her husband had brought her back from the east with a load of spices, but age and evil had left their marks on her."
So maybe Mel just hadn't worked out the whole anti-aging necklace thing yet?
Of course, Maggy looked a lot cuter on the show.
Perhaps the biggest piece of evidence in favor of the theory that Maggy and Melisandre are the same person (aside from the alliteration of their names) is that they both come from the same place – specifically Asshai, in Essos. While there's no evidence that Maggy was a follower of R'hllor like Melisandre is, the books do hint that Asshai is where she learned her dark magic. Even if the two women are not the same, then at the very least they learned the same craft from the same place.
It's definitely within the realm of possibility that Maggy and Melisandre could be one and the same, based on their abilities and the way magic works in Westeros, but a lot of things would have to fall into place for it to work. It's a cool theory, but it's probably not true.