Nobody puts Cersei Lannister in a corner — and yet, that's where the lioness finds herself on Game of Thrones. After relying on the promise of a trial by combat to get out of her troubles with the High Sparrow, Cersei's hope was crushed when her son, King Tommen, declared the practice illegal in Sunday night's episode, titled "No One." This means Cersei won't be able to use the Zombie Mountain to fight her battles for her, as planned. She has been effectively sentenced to death.
But seconds later, she and Qyburn had a rather interesting exchange. "That old rumor you told me about. My little birds investigated," he told her. She asked: "Is it just a rumor or something more?" He replied, "Much more."
Surprise! Cersei has a new game plan, and if you've been paying attention these past six seasons, you probably have an inkling of what it might be. [Consider this your spoiler warning.]
What do you do when you have been stripped of your power? You do anything possible to get that power back. You'd lie for it. You'd kill for it. You'd burn entire cities to the ground for it. And if you're Cersei, you'd do all three.
Although we never saw Cersei send Qyburn on his enigmatic mission, we have a hunch it's got something to do with all that wildfire hidden underneath King's Landing. For seasons, Cersei has been throwing fire-happy threats whenever her children are at risk. Last season, she told Tommen she'd do whatever she could to keep him from harm: that she'd "burn cities to the ground" if she had to. So is Cersei finally going to make good on her promise?
Now, we wouldn't be so convinced if the show hadn't just reminded us about all that wildfire in Bran's visions. Though it's considered nothing more than an old rumor in King's Landing, we know Mad King Aerys planned to "burn them all" to the ground because of the Three-Eyed Raven's massive data dump into Bran's mind. We know that Aerys had his alchemists create massive quantities of wildfire during Robert's Rebellion, and we saw the Mad King's pyromancers carefully stock the wildfire under the city. He had planned to burn down the city in the hopes of being reborn into a dragon, but Jaime Lannister killed Aerys before he could execute that plan -- and all that excess wildfire turned into nothing but a myth. Until now.
We saw a wildfire explosion in Bran's visions, one that seemed to occur underneath King's Landing. As far as we know, that hasn't happened yet, which suggests this was a vision of the near future. If Qyburn's little birds have found Aerys's cache of wildfire, Cersei could use it to blow up the Sept. (Honestly, the High Sparrow and the Faith Militant have overstayed their welcome at this point in the show, and it's time for them to go.) And because of her childhood prophecy, Cersei could blow up King Tommen as well.
At this point, she has lost her son to the Faith. When Cersei threatened to burn down cities and Houses, it was always in reference to losing her children. She's been paranoid that she'd lose them to death or someone else’s influence since Season 1. She's already lost Joffrey and Myrcella to death, and now it seems Tommen has been corrupted by the High Sparrow and Margaery. Cersei has no one left.
So why not burn them all? The Sparrows. The Tyrells. The Baratheons. Why not torch the city that turned against her? Cersei has nothing to lose, and potentially an Iron Throne to gain.