Who's really responsible for Daenerys Targaryen becoming the Mad Queen?
This is in no particular order.
1. Cersei Lannister: Cersei ordered the execution of Missandei, Daenerys' best friend, out of sheer malice.
2. The Night King: The Night King killed her dragon Viserion after Daenerys was convinced by Jon Snow that the real threat was in the North.
3. Euron Greyjoy: Euron ambushed and killed her second dragon, Rhaegal, leaving her with only one dragon left.
4. Varys: Varys betrayed Dany in an attempt to let people know Jon Snow/Aegon Targaryen was the rightful king.
5. Tyrion: He betrayed Dany by telling Varys before Dany
Not to mention the Mad King, Viserys, Mirri Maz Duur, Xaro Xhoan Daxos, Doreah, each contributing to her paranoia, trauma, and psychological issues as well as the deaths of Khal Drogo, Barristan Selmy, and Jorah Mormont.
And the ones who are the most responsible:
JON SNOW/AEGON TARGARYEN AND SANSA FUKKING STARK
Dany knew what would happen if the truth came out. She loved Jon Snow, but everything she fought for over the years would be for nothing if the truth were to come out. She begged him not to say anything. Jon Snow, for some silly reason, couldn't hide the truth from his cousins, Sansa and Arya (Bran already knew and so did Sam, but if Jon didn't want Sam to say shyt, he wouldn't).
He swore them to secrecy. Bran and Arya kept their fukking mouths shut (because Arya's a G and why should Bran give a fukk), but Sansa, who has been a two-faced bytch ever since Ramsey and Littlefinger, opened her goddamn mouth, knowing exactly what would happen, simply because she didn't like Dany.
Dany is so distraught over her best friend's death, the loss of 2 of her dragons, and the realization that she's not the true heir and now more people know...BUT she was still willing to work with her nephew if he maintained their close romantic relationship.
Aegon Targaryen had already been fukking Daenerys Targaryen. He could've overcome his Northern discomfort about fukking family and given Dany some love. She would not have turned King's Landing to ash if Jon Snow/Aegon Targaryen had just kept dikking her down.
But he bytched out. As a result, Dany snapped and a city filled with innocent people was destroyed.