Brian was standing on the beach with Tyrion, Martin, and Dany's other soldiers when he heard the horn blow. He saw Drogon throw Dany off his back, and Rhaegal throw Meg off. Then he saw the dragons turn around in the air and start flying back towards the island.
"Whoa, what's going on?" he asked nervously.
"I don't know," said Tyrion. "She's always been able to control those dragons before."
When the dragons got close to Dany's army, they started shooting blasts of fire at them! Drogon aimed a fireball right at Brian, and he only just managed to throw himself to the ground in time to dodge it. And even then, the fur on top of his head was scorched. Others weren't as lucky as Brian. Felldoh the squirrel got burned by a shot from Rhaegal, and Lord Boar got hit with a blast from Viserion.
Brian climbed back up to his feet to see the dragons flying over the warriors gathered on the beach and up to the castle on the cliff. "Uh-oh. Looks like they're going to burn the castle next."
"Rose is still in there!" Martin cried.
"And so is Varys!" said Tyrion. "And that sweet little girl Shireen!"
"Why have Daenerys's dragons suddenly turned against us?" Martin shouted.
Meanwhile, Dany was desperately trying to stay afloat in the water. Swimming was not one of her many talents.
She felt a pair of arms encircle her. "Hang on," Meg's voice said in her ear. "I'll get us both to shore."
Using all her strength, Meg paddled them both to land.
Brian ran to them. "Are you guys okay?"
"I think so," said Meg.
"Thanks, Meg," Dany gasped once she'd caught her breath. "You saved my life."
Just then, Stewie and McGucket appeared next to them on the beach, having teleported back from Winterfell. Stewie saw the enemy ships approaching the island from the water, and the dragons in the air about to attack the castle. "Well, it looks like things are going to shit," he surmised.
"That's about right," said Tyrion. "The dragons have gone rogue!"
"How did that happen?" Stewie asked.
Dany said, "It started when someone on one of those ships blew on a horn. That put them under some kind of spell."
"Well, maybe I can help," said Stewie.
"How can you possibly rein in my dragons when even I can't?" Dany cried.
Stewie smiled. "I'm going to try to warg into one of them."
And that is just what he did. He decided to warg into the white dragon, Viserion, as he was the dragon closest to the castle at the moment. He entered Viserion's body just as the dragon was about to shoot a fireball at the castle. Stewie made Viserion turn back around and fly back toward Euron's fleet. He felt exhilarated. He had never warged a creature as big as a dragon before.
Silence was getting closer and closer to the island when Euron saw Viserion suddenly turn and head back toward him. He didn't know why. "What are you doing?" he screamed at the approaching dragon. "I told you to burn the castle!"
"Maybe that dragonhorn doesn't work as well as you thought," said Jaime.
The horn was still lying on the deck, where Bane had dropped it after he'd fallen. Stewie could see it now, through Viserion's eyes. He made the dragon shoot a blast of fire at the horn, incinerating it as well as starting a fire on the deck.
"No, this can't be!" Euron cried. His voice was cut off when Stewie had Viserion breathe a blast of fire at him, killing him. Seeing this, Jaime decided discretion was the better part of valor, and he threw himself over the side of the boat and into the water to escape the dragon's flame. Many of the other soldiers aboard the ship followed his example.
Once the horn was destroyed, its spell over the other two dragons was broken. Drogon and Rhaegal reversed course and sped back toward the fleet to join their brother. Together, the three dragons started attacking all the ships. They burned many of them, and the rest of the ships quickly turned around and retreated, heading back toward King's Landing.
Frantically, Jaime paddled and kicked through the waves, trying to make it to the shore. At last, he reached dry land. He lay facedown on the beach for a few moments to catch his breath. Suddenly, he felt a foot stepping on his back, and the point of a sword poking his neck. He twisted his head around to look over his shoulder and saw Meg glaring down at him.
"Hello, Kingslayer," said Meg. "I've been looking forward to meeting you again."