There's a new Game of Thrones theory regarding Daenerys Targaryen's dragons that, if true, might spell trouble for our khaleesi.As Elite Daily points out, a new Reddit theory wonders what if the Night's King is riding one of Dany's three dragons.This actually connects to another longstanding theory about the show, which interprets Rhaegar Targaryen's vision that “the dragon has three heads" to mean the dragons will have three riders. For a while now, fans have speculated that Jon Snow, Tyrion Lannister, and/or Bran Stark may be among those to ride alongside Daenerys. But this idea about the Night's King is new, and it's not as farfetched as one might think.This theory posits that the Night's King could be riding Viserion after killing him. The King could then bring the creature back to life to make him part of his army of the dead. The Night's King has brought animals back from the dead before. Remember those horses his army rode in on?Lending some credence to this theory is a GoT fan account claiming this is all true. "Not going to say which dragon but yes," an account under the name "Game Of Thrones Feed" tweeted, "one of the dragons get killed and will be fighting with the nights king. ICE DRAGON."The Reddit post, which also contains other alleged season 7 spoilers, has since been taken down. This could be a sign that it was, at least in some part, correct. Though, if you believe HBO is releasing fake spoilers about season 7, then maybe it's all part of a larger plan.Either way, the idea of ice dragons is already exciting some fans and non-fans alike. As one person wrote, "me: Game of Thrones has amazing moments but is too often frustrating and blasé, sometimes even torture porny," before adding, "also me: but ice dragons."Fans have even been sharing a fake HBO poster for season 7, featuring the Night's King riding a frozen dragon spewing ice instead of fire.We'll find out what's really going down in Westeros when the season finally premieres next summer.