Queen Rhaenyra's followers were growing by the day. She had the most dragons, and powerful allies, which worried many of the Greens. Because of this, Aemond and Criston planned a trap to hopefully kill one of her dragons and their rider.
First, the Commander sent some men to attack Rook's Rest. Criston stayed back with more knights, waiting for the right time to strike. And, as expected, one of the Blacks soon came from Dragonstone on their dragon.
Soon, he signaled at his men to blow the nearby horn. It was a signal to Aemond, who was hiding far away with Vhagar. Blending in with the trees, they lied in wait until the alarm was sounded.
At that moment, King Aegon suddenly appeared on his own dragon, Sunfyre. He had no idea about the trap set out, and attacked the enemy. Frustrated, Aemond chose to wait a bit before commanding Vhagar to fly up and meet his brother and enemy.
Yet, that was when he saw you. It was you who'd come to protect Rook's Rest, not another Black as the Prince had expected. Aemond faltered, suddenly overcome by intense emotions at the sight of your dragon fighting Aegon's.
He was meant to attack you, to kill you. Yet, thinking back on the past, Aemond knew he couldn't. And when he remembered his brother's constant teasing, bullying and humiliation of him, he made his choice.
"Dracarys!"