The weapons really did sound like thunder. Mako stared out the window as they fired in waves, the thunder sound rolling through the sky in a near constant cacophony. The first airship's frame shattered under the onslaught and crashed to the ground outside the capitol. The second caught fire, exploding above the palace as it attempted to escape, setting the building aflame. The third opened fire, and the airship rocked under the impact. His hands gripped the railing tighter.
"Keep firing," Azula ordered. Her normal calm demeanor was laced with an undercurrent of fury. A part of her was appalled at herself, and at the things she'd been forced to do. She wasn't a fighter, or had never really wanted to be. But circumstances had forced her into this role. "I want that thing destroyed."
"We're losing altitude, your highness." The woman at the helm was one of Azula's lieutenants. She had some small experience in steering an airship, but she was struggling to keep them in the air. "I think they hit the stabilizers."
The other airship was smoking, gradually dropping from the sky. Mako pulled the woman from the helm. "Get the Fire Lord out of here and abandon ship. I'm going to try the Sato Maneuver."
Once Azula and the rest of her soldiers were safely off the ship, Mako pumped the throttle, trying to get enough power and altitude to ram the ship into the other one. For a few tense moments he thought he'd miss, but he got the ships lined up, and then ran onto the deck and jumped over the railing. The command ship crashed into the other airship, its momentum pushing them both out and into the ocean.
Mako watched from the safety of the rooftop he'd landed on, then turned back towards the city. Fire Nation forces were already moving against the remaining Red Lotus soldiers, fighting loud nearby and smoke rising in the distance as the sun started to set. He hopped to the ground and went in search of Azula.
It was darker by the time he found her looking at the burning wreckage of the palace. He didn't say anything, but he stood next to her. She reached out and took his hand, squeezing once, before letting go. She didn't look away from the fire as she spoke. "Thank you for everything, Mako. This would have been much more difficult without you."
Azula looked at him, then. The bandage had fallen from her eye, revealing a deep gash that ran vertically from her forehead to her cheek. The eye was sightless, faded white and caked with dried blood. She studied him with her left eye, before sighing and doing the thing she should have done sooner. "I have to tend to my people now, and the Fire Nation must show its true heart in aiding the rest of the world. I don't… I can't… We can't."
She bowed her head, and Mako cupped her face. He kissed her, and she held him stubbornly for as long as she could allow herself. Her voice was hoarse. "I can't go with you, and you cna't stay here. No matter how we feel about each other, we both know that your heart belongs to Republic City, and mine belongs to my people."
"Lets not be strangers," Mako whispered.
"Never," Azula promised.
Korra didn't know how she was going to save the Spirit World, let alone anything else. She had to find the source of the sickness and reopen the portals, but she couldn't figure out where to start. But even while sick, the Spirit World could provide. As though answering her unspoken prayer, a familiar looking cottage appeared from within the fog. She ran towards it. "Iroh! Oh tell me you're okay…"
The table where Iroh had his tea with his spirit friends was empty, the wood rotting and falling apart. There was a shattered tea-set in the center of it, but no sign of anyone around. It looked as though it had been abandoned for decades. She frowned, and made her way into the cottage. Like the table the building looked like it was on it's last legs. The last time she'd been here had been with Asami, ten years ago. It had been much more peaceful then. The building had been welcoming and cheery, the spirit world colorful and full of promise. Their love had been new and strange, and though it had turned into a slow burning ember, it was still strong. It pained Korra to see this place looking like it had been abandoned.
But inside, there was a presence. Shadowy and faint, but as Korra lit a fire in her palm, she could recognize Iroh standing there in front of her. "..Iroh? What happened to you?"
"As the spirit world suffers," he replied. "So do I."
Korra held her hands out. The old man was frail and thin, ghostly transparent. "Not if I can help it."
Just as she'd brought light to parts of the Spirit World during this journey, she brought warmth to Iroh and his cottage, her happy thoughts of the time they'd visited with him, and how he'd helped her when she'd been lost and alone. Iroh gradually grew more solid, thicker around the middle, his beard and smile returning to their full luster. He beamed at her. "Ah! You have grown much since last I saw you. I would ask how you and your wife are doing, but I am afraid we do not have the time."
"What's happening here?" She gestured around, indicating the way she'd found him. "The Spirit World is sick, but how?"
"I can only guess, but there are new and malicious forces at work here. It began a few weeks ago. Spirits growing sick. Black clouds in the sky. And then a few days ago, darkness swept across the Spirit World, and many spirits began to die."
"I need to find the source." She didn't know how she'd beat it. She still wasn't sure what she'd have to do with Amaya once this was said and done, and despite everything that still weighed on her mind.
Iroh seemed to pick up on her unsaid questions. He took her her hands. "You are the Avatar, but more importantly, you are Korra. Look within yourself for the answers to the questions you are afraid to ask. When the time comes, you will know what to do. Whatever that answer is will be uniquely yours."
He turned towards a window. "As for the source, I believe we both know where it is."
Korra followed his look. And Iroh was right. She knew exactly where she needed to look.
She turned back to Iroh, and then picked him up in a powerful hug. "Will you be okay? I don't know what'll happen when I leave you. You might get sick again."
"Nor do I. But perhaps it is time for this old spirit to fade away."
Not letting herself look back, Korra stepped out of Iroh's cottage, and took a step forward. Distance mattered little in the Spirit World and the ground rushed below her. With her next step she stood at the Tree of Time. Where there should have been the open spirit portals, there was nothing. The area looked even deader than usual, a thin layer of dust or ash on top of everything and the mountains surrounding more jagged and toothlike than she remembered. She thought she saw lava pouring from one of them.
"We meet again."
To Korra's left stood a man. He was familiar to her. At times he'd haunted her nightmares every day of the week, until she had moved past her fear and into acceptance. He couldn't scare her now, and staring at him, she only felt pity.
"Zaheer. What have you done to yourself?"
Her old demon resembled one now. Zaheer's form had grown larger, dark like the shadows his skin a deep shade of purple. He was partially transparent and he seemed to ripple with blue-ish black light. His hair, black like midnight, hung in loose tendrils down his back and his eyes glowed with an otherworldly light. Where he stepped, the earth died. "I let go. My last earthly tether was my body, and like some others before me I crossed the boundaries between men and spirits."
"You're the sickness," Korra lifted her fists, ready for the fight she knew was coming. "Why? You were one of the most spiritual men I ever met, as misguided as you were. Why would you poison the Spirit World? You're a dark spirit now."
"Not a poison. Not a sickness. A cleansing. Clear the forest for new growth, isn't that what Amaya told you?" He spread his arms out. "I discovered something, during my long explorations of this world. Not just the knowledge to teach a gullible young girl how to manipulate energy and shadow. Not just how to siphon bending from those spiritually attuned to you. I discovered the true history of our world. How one man threw everything out of balance. Mankind should never have been granted bending."
Korra narrowed her eyes. "You're going to take us back to when everyone lived on the Lion Turtles and spirits ruled the wilds? You realize they had warlords who abused their people back then, too, right? You wanted to give power to the people, but you've never stopped and thought about how to prevent that from being abused. There's no perfect answer, Zaheer. Search all you want."
"You're only half right." Zaheer attacked first, shadowy tendrils shooting out of his fists like razor whips. Korra flipped out of the way, ducking low and then sweeping with fire. "The Avatar was never supposed to exist. You're the disease, Avatar. Bending is the disease. Humans are the disease.
"What are you trying to cleanse?" Korra's mind raced, as she dodged more of Zaheer's attacks. She retaliated with earth and water, just enough to keep him distracted. And to let him keep talking. The more he talked, the more she learned.
"The source, Avatar. The source." Tendrils wrapped around her arm, and she grabbed them, wrapping them further around her wrist and then yanking Zaheer forward. Her elbow connected with his face, then she spun around and threw him into a rock outcropping. She bent it around him to hold him in place.
The world shifted around them and they were in some kind of gorge. Zaheer spun toward Korra with a powerful kick. She deflected it, springing to the right. The only thing he could bend were the shadows, she realized. Since he hadn't crossed through the portals he couldn't airbend. That gave her an advantage. She advanced forward, attacking with all four elements.
The source she thought to Raava. It's the Lion Turtles, isn't it.
Yes. Like all things they are part of a cycle. But I do not know what will happen if his sickness kills them. Even if he removes the source of the bending, I do not know his intentions for humanity as a whole.
It could be that that Zaheer thought that would killing the Lion Turtles would remove bending from the world. She couldn't let that happen. The sudden imbalance would be catastrophic, and while she knew people were resourceful enough to adapt, she wasn't sure if they'd be able to react quickly enough to Zaheer completely removing the barriers between the Spirit World and the material world. Korra was certain that was part of his plan. Once, the barriers hadn't existed. Humans lived on the fringes of the world, protected only by the Lion Turtles. But if the Lion Turtles were dead, and humans had no bending, and both worlds merged… he might very well end humanity. Whatever his goals had been before, this corruption had turned him into a literal monster.
Korra surged forward, an unrelenting assault that had Zaheer constantly backing up. The scenery around them kept changing. Zaheer took them to a swamp. Korra took them to a plateau. They fought in a desert and under the ocean and in a place where light and shadows were reversed. Zaheer's attacks flowed like poisonous water, and Korra moved like living elements. In their last battle, Korra had been out of control. In this one, Zaheer was the one who was lost, drowning under the oppressive weight of his spirit corruption.
"Look at you!" Korra grappled with him, twisting his arm behind his back and flinging him into a mountain. She barreled into him, her shoulder connecting with his chest and the mountain crumbled around them. "Look at what you've turned into! You wanted everyone to be free but now you're a prisoner in your own body! Do you really want genocide?"
They crashed through a forest, and Korra skidded along the ground, surfing on the underbrush with her feet. Zaheer landed less gracefully, seemingly overburdened with his new shape. He got up roughly. "Give up, Avatar. I cannot tire, I do not need to sleep."
"On the contrary," A voice said. "Even spirits need their sleep, and you've disturbed mine!" Many feet chittered on the ground. The spirit resembled something like a centipede, though it had a human like face set into the top of its body and graspy mandibles arranged in an oval around its head.
Korra immediately purged her face of all emotion and her voice became monotone. "I'm sorry to disturb you. Zaheer has poisoned the Spirit World and I've been trying to deal with him. He's proven to be really annoying."
Koh twisted around, towards the former airbender. "Poison. I can smell it on you, it follows your every step. What you touch withers."
"Change requires sacrifice," Zaheer replied. "In the new world you would not have to skulk around in forests. We'll all be free."
"Free?" Koh leaned in, face to face with Zaheer and gave him a terrifying smile. "Tell me mortal, of this freedom."
"Freedom to destroy. But where's the fun in that?" Korra was certain that Zaheer would recognize Koh's name, but she was praying he didn't know what the face-stealer looked like and assumed this was just a powerful spirit. "What Zaheer wants is anarchy."
"Quiet." Koh turned towards her. "I want to hear it from him."
But Zaheer was an educated man. He kept his face impassive. "Freedom. For spirits, for mortals. First we must unshackle ourselves from outdated ideals, such as governments and Avatars. Then we can make the world the way it should have been all along."
Koh tilted his face, studying Zaheer. "And the Avatar, she wants to stop you. She wants to murder your new world and strangle it in the crib. Doesn't that make you… angry?"
"I have transcended emotion," Zaheer replied.
"What about Amaya?" Korra asked. "Do you feel nothing for her or what you've twisted her into becoming? Or is she just another tool to be discarded when she's no longer of use. Like P'Li?"
"I have let go my earthly tethers, and all of that is ancient history."
"They died for you, Zaheer. P'Li, Ming-Hua and Ghazan. Does that mean nothing to you? Amaya sees you as a father-figure. Is she a means to an end? Or will you let her go, just like you left your friends, unmourned and forgotten."
The debate between the Avatar and Zaheer was like a very interesting sport, one that Koh was paying close attention to.
Korra's face remained unmoving, and her eyes remained locked on Zaheer's face. "How does it feel, Zaheer? To be alone, and defeated. I beat you once, I brought you back to earth and this time I'll bury you. But there won't be anyone waiting for you, and no one will mourn you. You'll be forgotten. But that's okay, isn't it? you taught me to let go, after all."
And something passed over Zaheer's face. Pain. Regret. It lasted just a fraction of a second but Koh jumped on him. Zaheer's scream was abruptly cut off, and when Koh turned back to Korra, he wore the man's face.
Zaheer's body lay on the ground, the features of his face erased. Korra wondered what would happen to him. A human would remain in a state between death and sleep for the rest of their lives. But Zaheer's body had died, and what remained was his spirit.
"He'll fade away, his poison inert," Koh told her. Zaheer's face smiled. "I rather like this face. Thank you. But I do think that lovely wife of yours would make a wonderful addition to my collection…"
"I didn't come here to fight you, don't give me a reason," Korra warned, her inflection still flat.
"You were clever enough to lead him here. I wish no quarrel with you. But I had to try you understand." Koh retreated, quickly disappearing into his tree. His last warning echoed in the woods. "But do not be too clever, for that just leads to trouble."
The spirit world felt cleaner, healthier. Korra turned away from Koh and the omnipresent danger of the face-stealer. She knew she could reopen the North and South portals. It was the Republic City portal she was worried about. But when she'd done it the first time, she'd opened a new tear in reality. Even if the portal was closed, that thinner layer should still be there. She just had to find the right loose thread, and pull.