Warning: Big Game of Thrones spoilers below!
Did anyone else think Daenerys was about to go wild at the end of the most recent episode of Game of Thrones? The Dragon Queen is being tested in a major way, and her patience is failing. The once benevolent leader is now seething with a righteous anger that leads Varys to hint to Tyrion that their beloved queen's behavior is more than a little tyrant-esque. After losing a large swath of her army, Ser Jorah, Missandei, and Rhaegal in just a matter of days, Daenerys is tired of playing games with Cersei. She's ready to take the Iron Throne by any means necessary, but that could also mean she's about to make the Mad Queen theory a reality.
The original Mad King, Aerys, was Daenerys's father. During his reign of the Seven Kingdoms, Aerys grew paranoid, eventually seeing everyone as the enemy, and often uttering his rallying cry of "burn them all" — he even tried to use wildfire to do so. To her credit, Daenerys doesn't appear to have reached major paranoia, but the ruthlessness of her plans to take the throne hints at the worst part of her Targaryen lineage.
While all of the attention is being focused on Cersei's unquestionable cruelty, there are plenty of signs that the Dragon Queen is the one that people should fear. For example, she tries to force Jon to keep his claim to the throne a secret because she believes it's her destiny to rule the Seven Kingdoms. That desire for power can be corrupting, and there are plenty of signs that suggest Daenerys might get rid of Jon before allowing the North to champion him as the true ruler of Westeros. More immediately, she's about to show King's Landing the full extent of her strength by potentially unleashing dragon fire on a city full of innocents. With her obsession with burning her enemies alive, Daenerys is becoming more and more like her father every day. Now, that doesn't necessarily mean the Mad Khaleesi theory will come to pass, but it should give you pause.
The Theory
The Mad Khaleesi theory suggests that Daenerys has been behaving like her father for years now, but because so much of the story is from her point of view, it's hard to see her actions as cruel. After all, the Dragon Queen never targets innocents, with her victims being vicious khals, slave traders, and the Lannister army. But there is an undeniable brutality in her tactics, and nowhere is that more evident than in the deaths of Randyll and Dickon Tarly. She burns the father and son alive when they refuse to bend the knee, just seconds after she claims she's not in Westeros to murder.
In season eight, she has a character challenging her vision of herself as a savior every step of the way, and that person is Sansa Stark. The lady of Winterfell's distrust in the Dragon Queen comes from an understandable place. She sees Daenerys as someone who is manipulating her brother's love for her own gain, and as a ruler who will demand fealty no matter the cost. These are clear warning signs for Sansa, and for the audience, that it's possible that the Daenerys we know and love is more dangerous than we could ever have imagined.
The Evidence
Varys has firsthand knowledge of what it was like to work for the Mad King, and in "Eastwatch" (the fifth episode of the seventh season), he shares his experiences with Tyrion. He recalls how he would find traitors to bring before the Mad King, and then he would stand aside and watch as he burned them alive. In "The Last of the Starks" (the fourth episode of the last season), he again comes to Tyrion with his fears about their queen. This time, he points out that Daenerys's talk of destiny points to her being a tyrant in the making, because every tyrant he's known had the same ideas about themselves. He warns the Hand of the Queen that the Mother of Dragons no longer seems to have the people's best interests at heart — instead, she craves the power above all.
As her closest allies continue to fall, Daenerys is becoming more and more distrustful of those around her. She no longer seems to value the council of Varys or Tyrion, and she sees herself as an outsider on this side of the sea. Most concerning of all is her jealousy of Jon Snow. She watches as Tormund and the North shower him with praise in the aftermath of the Battle of Winterfell, and it leaves her so angry that she storms off. Later, she begs Jon to keep the secret of his parentage to himself because she knows that the people of Westeros are more likely to choose him over her. Her growing paranoia and inability to trust those closest to her mirrors her father's descent into madness in a disturbing way.
The loot train battle in season seven sees Daenerys raining fire down on the Lannister army indiscriminately. She burns them all, leaving only a handful of men standing at the end. She offers those men an option: join her or die. The lack of middle ground hints at the same extremism of her father, who showed his enemies no mercy. What's most distressing is that Daenerys claims to give these men a choice, when in actuality their only option is to bend the knee. She's ruling with fear, and fear was her father's weapon of choice. Now she's heading into another battle with the Lannisters, and there's no doubt that she will lead with terror. She only has one dragon left, but she's ready and willing to allow Drogon to burn King's Landing in retaliation for what Cersei did to Missandei.
Daenerys has always been fond of flames. It is fire that births her dragons, and fire that frees her from the khals. The Mother of Dragons doesn't just kill anyone who gets in her way: she burns them, just like her father did, and that's not about to stop anytime soon.
What It All Means
Daenerys is her father's daughter in many ways. Those who are firmly on her side have nothing to fear, but she demands absolute loyalty. If she receives anything less, she lashes out. She's made it clear through her interactions with Sansa and Jon that she wants to rule all Seven Kingdoms, and she'll accept nothing less, even if it means destroying people and houses to get her way.
There's also not doubt that she's ready to use her last dragon to kill her enemies. In some ways, this is a show of strength, but in others, it is a warning sign that if she's not careful, Daenerys could still become known as the Mad Queen. Right now, the Mother of Dragons is backed into a corner by Cersei and her own anger and frustration with the way her homecoming has gone down so far. She's about to show us who she really is, and we need to be prepared for the possibility that we won't like what we see.