Seated on his throne in the Caldera bunker, Ozai could not wait for his rebellious son to conclude his idiotic rant. Zuko was brandishing his dao and a stern scowl. The soon-to-be Phoenix King was holding back laughter.
"...He's the one who's been a real father to me..."
Ozai had dismissed his guards to listen to his son's not-unexpected declaration of treason.
Let him believe he has me at his mercy.
He had been yelling about the Avatar being alive, honor, "cruelty", Their Great Empire being "evil", and joining the Avatar and his band of guerillas.
"I'm going to join the Avatar. And I'm going to help him defeat you."
So amusing. What's another lesson that would break Ursa's heart?
"Really? Since you are a full-blown traitor now and you want me gone, why wait? I'm powerless. You've got your swords. Why don't you just do it now?"
I am powerless, but not my green tools.
"Because I know my own destiny. Taking you down is the Avatar's destiny. Good bye."
Three. Two.
Zuko sheathed his swords and turned to walk out of the throne room.
One...
Two Dai Li agents shot up from the floor and two down from the shadows above. Before Zuko could fully react, the agents covered him in stone. They wrenched the dao from his hands, forced him to his knees, and earthbent him a few feet from Ozai.
"Going so soon," hissed Ozai with a thin smile. "This conversation has been too intriguing to end so abruptly."
Zuko trembled, pupils wide as limons.
Pointing to the agents, Ozai continued, "Were you so foolish to believe that I would let Azula keep all of her new toys to herself?"
Dripping with venom, Ozai spat, "I believe another lesson is required, my son. Not a lecture. No, something more practical. Have you ever heard of heatbending? It is a rare form of firebending I neglected to teach even to your sister." He considered the omission necessary to maintain an edge if Azula challanged him for the Dragon Throne.
He could feel Agni breaking Tui's shackles.
Mockingly looking around the room, he asked, "Are there any volunteers?" He nodded to one of the Dai Li, who earthbent Zuko's hand into the air.
"Excellent. Now, the lesson."
Ozai bent on one knee, glared into his son's soul, and placed his hands on Zuko's chest. It was the proper procedure for an execution. With some modifications. The Firelord could feel the heat coursing through his son's body. Could feel his inner fire. Beckoning the heat to himself, Ozai forced Zuko's body heat out his nostrils and sensed his son's limbs, then chest, then inner fire grow cold. His flame became a flickering ember and his body limp. Zuko's head hung from his earth-encased shoulders.
The Firelord strolled back to sit on his throne and curtly declared, "Boiling Rock."