There's a new villain in Westeros, and he's got his eyes trained on the Iron Throne. Entertainment Weekly confirmed Euron Greyjoy is getting a major upgrade just in time for Game of Thrones Season 7. He's trading in his Iron Island grey-tones for black robes and a slightly less serious, but still maniacal attitude. Cersei's pirate suitor is all about amassing as much power as possible, but there's an intense fan theory that hints Euron may be after much more than the Throne.
Tumblr user Poor Quentyn is responsible for what is known as the Eldritch Apocalypse theory, and it's the one Euron theory you need to know before Season 7. While it's tied to the book version of Yara and Theon's uncle, it could easily be adapted for the show. The Eldritch Apocalypse suggests that Euron isn't just a pirate, but he also practices dark magic. As Vulture explains, he's planning to orchestrate a massive naval battle in order to offer up a large-scale blood sacrifice to the gods, in exchange for luring the dead to his side. Basically, Euron's end goal could be to align himself with the White Walkers and usher in an apocalypse wherein he could potentially be the leader of an icy, undead world.
It may seem a little far-fetched, but throughout the books visions of a "sea of blood" are alluded to by multiple people, including Melisandre. More importantly, the Season 7 trailer previews a fiery naval battle that definitely involves the Greyjoys. Remember, in the world of Game of Thrones the ultimate blood magic involves sacrificing your kin. And Euron seems more than willing to off his niece and nephew.
In his interview with EW, actor Pilou Asbaek took a stab at explaining Euron's motivations. He said,
The article reveals that while Euron initially had plans of allying himself with Daenerys, he's now more interested in getting on Cersei's good side. Since she does currently hold the Iron Throne, Cersei is his best bet at obtaining power, but he's going to have to offer her something worthwhile to get in her good graces. What better gift is there than an army of White Walkers?
While Jon Snow is busy trying to prevent the apocalypse, Cersei would likely welcome anything that she believed would help her maintain her position as queen. She's already had others dabble in necromancy on her behalf, and that resulted in her undead protector — the zombie Mountain. If she truly believed she could control the Night's King and his people, there's every chance she would sacrifice the Seven Kingdoms for her own gain. And, wild card that he is, Euron could be the man to make all her dreams of power come true for the low, low price of sacrificing his fleet and the remaining members of his family.
If the Eldritch Apocalypse comes to pass, then Season 8 of Game of Thrones could easily see Euron, Cersei, and the White Walkers going up against Jon, Daenerys, and the rest of the Seven Kingdoms as they try to stop these two power-mad monarchs from ending the world.