I'm on board with a Redditor's theory that Daenerys' descent into madness was caused by Varys poisoning her food. It's the only explanation I'm willing to accept as the truth to why Dany would have burnt down King's Landing along with all its innocents.
This is the way I'd have wanted to seen GOT end. And maybe there'll be a few more chapters after this one too.
When the fire stopped burning, King's Landing was covered in a layer of ashes. It almost resembled snow if you didn't look too closely. If you ignored the charred corpses of women and children in the street. If you ignored the pungent stench of death in the air.
Jon walked towards the throne room with the weight of his conversation with Tyrion bearing upon his shoulders. Even from a distance, Danerys looked beautiful. Her silver locks braided intricately, without a single strand out of place. And when she turned around to face him, the flush on her cheeks against her porcelain skin reminded him of a time her face would bring him nothing but joy.
He had come with the intention, no, the determination to kill her. To save Westeros from her madness and to save herself from who she had become. But walking toward her, Jon had noticed that despite her rousing speech to her armies just now. Daenerys did not look well.
Beads of sweat clung to her forehead and her lips were pale. Jon could tell it took her great effort to concentrate and as much as she was trying her best to stand tall and dignified like a Queen should, she was crumpling over.
"Daenerys...what's wrong?" Despite his objective of having wanted to come and put an end to her tyranny, Jon instinctively wrapped his arms around her for support. Her hands had flown to her head as she closed her eyes, pain rocking through her mind and body.
"I...I'm...What have I done Jon..." sobs wrecked her through her core as she convulsed in pain. The regret and guilt evident on her face. Before Jon could react to her words, Daenerys clawed at him, as though she had been possessed by a maddened soul. "Burn them all, burn them all down!" Her pupils were dilated and there was spittle at the corners of her mouth, brought forth by the intensity in which she had said those words.
As soon as the Mad Queen had appeared, she left. Dany's body slumped against his again. "Jon...Please...Help me..." Danerys said, the fear in her eyes foreign to Jon. He had never seen her so afraid before. Not when the Long Night came upon them. Not when she realised his parentage. This fear crippled her, and in his arms, she was Dany, small and vulnerable again.
Her swing between madness and sanity, seemingly beyond her control, raised questions in Jon's head. Her pulse was erratic and her breathing laboured.
"He tried to poison me, Jon. He must die."
Jon had remembered what Danerys had told him before sentencing Varys to death. He had tried to poison her, but was stopped, thanks to Tyrion who told her the truth about the Spider's betrayal. But did they stop him in time?
"Daenerys, can you hear me? Dany, please! Wake up!"
Jon shook her in his arms, beckoning her to respond. He had come to kill her, but even without having to do the act, he was shown what it was like to live in a world without her. Daenerys lay motionless in his arms, and despite her laboured breathing, he had feared the worst.
He opened her mouth slightly and peered into it.
"Poison shows at the roots Jon Snow. If you ever come across someone clever enough to use Basilisk's blood to send someone into a spiral of madness, all you need to do is check the back of their tongue." Maester Aemon had told him once of the rare poison. A story he had dismissed as just that — a tale.
But Dany's tongue was blackened.
An impossible rage shot through Jon when he realised Varys had been demented enough to poison Dany with Basilisk's blood in order to set off madness within her. The blood of King's Landing was on his hands. Suddenly, Danerys' execution of him seemed too merciful.
"Bring me Tyrion!"
Jon shouted towards the Unsullied guards who had come towards the throne room. Tyrion would know what to do. He could fix this. Show the world their Queen wasn't the one who burnt King's Landing to ashes. She wasn't the Mad Queen. She had been poisoned. And he know Tyrion would be able to fix it.
Despite convincing Jon to kill her, Tyrion did love Daenerys. She had shown him hope, trusted in him, confided in him. Gave him the Hand's Pin when he was nothing but a dwarf. She had always been the queen he wanted, until she let madness overcome her.
But now seeing her in Jon's arms, tears stung his eyes and he broke into sobs.
"Tyrion, it's not like that. She's been poisoned. By Basilisk's blood. It seems Varys got what he wanted before you could stop him."
Poison.
Tyrion rushed towards his Queen. He had heard of poison by Basilisk's Blood before, but always thought it was a myth. The madness it could bring out from people, as if they were possessed by an unseeen spirit of rage and anger. A mouse would attack a lion after Basilisk's Blood.
Now it all made sense. Why Dany had been so ruthless despite the ringing bells. Why she had turned her head from council, refused to give mercy. Tyrion wished he could have seen it first. She hadn't been herself for awhile now, her body weakened, her mental state turbulent and unpredictable. How could he not have known that poison lay within his Queen's food?
"My Queen, I'm so sorry I doubted you."
Tyrion kneeled beside her and took her hands in his.
"You must head back to Winterfell. The Maesters will be able to help her. Basilisk's blood may cause madness, but not death. Her health must have been affected from how long they've been tainting her food with this poison. I am sure they will be able to fix this."
"In the meantime, I will send out the ravens. Let the worlds know that Daenerys Targaryen was poisoned. She was not herself when she burnt down King's Landing. That she's still our rightful Queen. And anyone who disagrees with us can fight us for it."
Tyrion spoke, determination in his eyes.
"How will we get to Winterfell in time? I'm not sure how long she'll last." Jon asked, his voice shaky, his worry clung to every word he spoke.
"By dragon" Tyrion responded.
"I've never mounted Drogon before, only his brother. I'm not sure he would take us." As if sensing Jon's hesitation, Drogon let out a roar before the sound of his flapping wings were heard. He landed with a loud thud in the throne room and lowered his wing for Jon, who carried Daenerys and mounted the black dragon on his back.
"Fly fast my boy." Joy leaned forward and instructed Drogon in a low voice. His hands moving to stroke the large dragon's neck. He remembered back when Dany had taught him how to fly. Her eyes bright and teasing, laughing at him for clinging on to Rheagal for his life.
"Dany, you're going to be ok. I won't let the Gods take you from me." Jon held on to Daenerys as her eyes briefly fluttered open. She was back in his arms, on Drogon. If this were a dream she never wanted to wake, but she knew she had to.
"Save us, Jon. Save us. Our child." Dany pleaded before moving her hands to her stomach, clutching at it protectively before the tears streaked down her face. Jon's eyes widened in shock as he felt the rage bubbling inside him once more. He let out a deep roar and beckoned for Drogon to fly even fasted. A second roar exploded through the sky, louder than the one Jon had let out.
Drogon had felt Jon's pain and anger. The dragon in Jon had awakened and he mentally thought of every single person that would pay should he lose Dany and their child. That is if they were not already dead.