It was completely satisfying to watch Daenerys set fire to the rain, and by "the rain," I mean "Khals who were casually discussing her potential gang rape in front of her for three episodes," on the Season 6 episode "Book of the Stranger." But Dany's newly found penchant for destruction has a few fans a wee bit nervous that she's going the way of her father, The Mad King. So will Daenerys become the Mad Queen on Game of Thrones? There are a few hints that her heroism may be leading to her demise.
Readers of the series note that Daenerys' actions are written in the same objectively atrocious way as The Mad King's, but that George R.R. Martin has crafted her to be a more likable character, so her destruction is perceived as noble and heroic. This definitely sets up the potential, however, for Dany to morph into a villain.
The other big hint that Daenerys' takeover will turn sour is in the quick flashes of information Bran is experiencing from when the Three-Eyed Raven gave him the whole history of the world all at once just before he died. While Bran can't effectively control his processing yet, this handy guide breaks down absolutely every shot. One of the flashes shows wildfire engulfing a corridor, presumably of The Red Keep. This is a reference to the fact that Mad King Aegon Targaryen stashed wildfire all over King's Landing to unleash if his seat was ever threatened, thinking that he wouldn't burn, but rather, would rise from the ashes of the city like a dragon.
But Jaime Lannister slayed the king before he could deploy any of it, so the wildfire-burning scene isn't a flashback. The popular theory is that the shot is actually meant to be a vision of the future, suggesting that Daenerys might finish what her father started. Part of her plan to take over Westeros will most certainly require the destruction of some Lannisters, and Daenerys seems to like using fire as a weapon, since, conveniently, she can use it on her enemies while remaining unscathed. As Daario astutely pointed out in Episode 6, Daenerys Stormborn is a conqueror. But it remains to be seen if she can keep her power in check if she claims The Iron Throne.