A/N: This is a rework of a flashback scene from the series, but also a companion piece to Rising Tide (first referenced in chapter 15).
Azula pulled Zuko behind the thick curtain in the palace throne room. His heart was still racing from his failed attempt at impressing his grandfather, and he wanted nothing more than to leave this foreboding room post haste.
"What are you—?"
"Shhhhhhhh." Azula put a finger over her lips.
Zuko could not shake the feeling of dread in the pit of his stomach. They should not be there. Then, he heard his father speak.
"Father, you must have realized as I have, that with Lu Ten gone, Iroh's bloodline has ended. After his son's death, my brother abandoned the siege at Ba Sing Se, and who knows when he will return home. But I am here, Father, and my children are alive."
"Say what it is you want!" Azulon snarled.
Ozai stood and began approaching the throne. "Father, revoke Iroh's birthright. I am your humble servant, here to serve you and our nation. Use me." He then bowed in submission.
With a crooked finger pointed in the air, Azulon's temper flared along with the flames around him. "You dare suggest I betray Iroh? My first born? Directly after the demise of his only beloved son? I think Iroh has suffered enough! But you... your punishment has scarcely begun!"
At this proclamation, the flames surrounding the throne raged with intensity. Zuko had spent very little time around his grandfather, but enough to develop a deep-seated fear of the man. He did not want to stick around to hear more.
Azula, however, knew she had the favor of her father and felt secure in that. She felt fairly benign toward her grandfather having also spent little time with him. She had always sensed there was tension between Ozai and Azulon and would even venture to say that Iroh was the favorite son. Coward, she thought as Zuko slipped away.
Still on his knees, Ozai continued to petition Azulon, keeping his tone cool and even. "Please, Father. I only had the Fire Nation's best interest at heart. I meant you no disrespect. I am your loyal son."
"I will teach you respect," Azulon sneered. "And the punishment shall fit your crime. You must know the pain of losing a first-born son… by sacrificing your own!"
Azula wondered for a split second if it was bad that she took such pleasure in this development. Her remorse only lasted that one second, though, and she thought of how much more delightful it would be to see Zuko's face when she told him about it. She simply could not wait a second longer.
With the eavesdroppers now gone, the scene began to twist even more.
"What would you have me do, Father?" The corners of Ozai's lips turned into a sly smile.
"Kill the weakling!" Azulon roared. "Roku's power was wasted on you. You have tainted the bloodline, and I want you out of my sight!"
Ozai didn't budge. He didn't allow his temper to flare, either. "But Father, you and I both know that it was not I who tainted the bloodline."
"You dare to keep speaking to me?" the enraged Fire Lord hissed.
"You dare to deny the truth!" At this, Ozai stood to his feet. "Oh yes, Father. I know all about your mother. That you are the bastard son of a Water Tribe whore. Perhaps your loyal subjects would be interested to know this about their esteemed Fire Lord. The Fire Sages may even find this as grounds for abdication. I already have their blessing through the prophecy about Roku's heir."
"You will not speak a word of this. Are you threatening me?"
"Not threatening, dear Father. Just… bargaining. Pass the throne to me, and your secret will be safe until the day I die."
"Today may very well be the day you die!" The flames rose higher, and Ozai had to back up a few paces to avoid their imposing heat.
"Oh, Father, you forget that you have taught me well. Ursa knows of my petition. If you kill me now, then she will expose you for what you are. She wants her bloodline to continue just as much as I do."
"Kill the weakling."
"Perhaps you misheard. Ursa would not—"
"I will grant you Iroh's birthright if you kill the boy. He is not fit to rule. The bloodline will continue through the girl."
"I couldn't agree with you more."
"Ozai! Azula tells me that your father told you to kill Zuko! What is the meaning of this!?"
"What! Why that little—" Ozai immediately settled his temper and redirected, more calmly, "It is the price I must pay for the throne."
"You c-c-can't… how could you?" Ursa's temper unleashed.
"Ursa, you know it is my destiny to become Fire Lord! The boy is nothing!"
"He's your son!"
"He is weak and unfitting to be Fire Lord."
"Then send him away! To my parents… to a quiet life in the village… no one will ever speak of it… but don't—"
"No, it has to be this way. My father's orders. You know how he is."
"What if… I… could make Azulon go away. And you could be Fire Lord now."
"What do you mean?" A flash of fear flickered in Ozai's eyes. This happened rarely, yet it did not go unnoticed. "Like kill him? Ursa, that's high treason."
"I can make a poison. It's colorless, odorless, and tasteless. I can… slip it into his tea. Everyone will think he died of old age. If he truly revoked Iroh's birthright…"
"Mmmm, yes. It just might work…" Ozai stroked his chin.
"But you must promise to spare Zuko's life!"
"Then you must promise to leave the Fire Nation!"
"What!? B-b-but why?"
Ozai's eyes now flickered with something else. He was scheming, and they looked as shifty as a foxcoon. "If there is any suspicion surrounding his death, I'll need you as a scapegoat. If you flee, then you will look guilty. If you are still here, then we may look like accomplices. Or if I have to pass blame to you, then you suffer the consequences. You must run in order to save your own life."
"Then I take the kids with me."
"No! A truly evil woman would commit murder and then leave her children behind. You must play the part fully, Ursa!"
"So that is what I am to you. Just a pawn in your game to be cast aside, then. You don't care what happens to me. You don't care what people think of me. You would just have me leave the life I have here. My children…" Her voice broke, and tears filled her eyes.
Ozai was unmoved. His wife's emotions hadn't impacted him for years. "I can write you letters if you want. Updates on the children…"
"What makes you think I'll tell you where I'm going?" Ursa figured if she had to leave, then she would be free of him, once and for all.
"Fine. Have it your way. And don't you dare think of coming back." Ozai shook a finger at her, reminiscent of the way Azulon had done to him.
"I won't… unless… you don't keep your end of the deal. You will not lay a finger on the children. I will make you this poison, I will keep my vow not to firebend, and I will leave your life forever if you promise to NEVER hurt Zuko and Azula."
"Fine."
"I mean it, Ozai."
"That's Fire Lord Ozai to you."
Ursa went to go make the poison. And Ozai went to hire a spy to follow her.