Foreword

Alright, so here is my first attempt at a crossover that blends two worlds together retroactively, rather than just teleporting (a) character(s) of one story into a strange new world. Inspired by jdeberge's picture Ozai's Operatives on Deviantart, I plan to mix Avatar: The Last Airbender with Spec Ops: The Line. Being familiar with the latter is not a requirement. In fact, the story might even be more enjoyable if the ending is not spoiled. Those of you who know the story of The Line, please try not to spoil the story in reviews.

The story is also very much AU for the Avatar verse. The big point of divergence is the appearance of Sozin's Comet. Or as it is called in this story, Azulon's Comet. The timing of Roku's death and the Comet's arrival was very inconvenient for the Fire Nation. Since the Comet was so far off, the Air Monks had no reason to be seriously afraid of war. Aang was informed of his avatar status when he was sixteen, as traditional. By the time the Comet arrived, Aang was thirty years old and more or less a fully realized Avatar. The rest of the divergence will be explained in-story.

Because of the story of The Line, the Mature rating is very much justified. The story will get very, very bleak before it's over.

Also: First Spec Ops: The Line crossover on ffnet. Though I find cheering about that game to be poor in taste.

The Spirit World

Avatar Korra was, once again, having trouble with her duties as Avatar. The two water tribes were facing civil war and she found herself uncertain about which side she should take. In a moment of inspiration, she realized that everyone around her was unable or unwilling to give her unbiased advice. Thus, she had ventured alone to the south pole, a place that supposedly had a strong connection to the spirit world. An attempt to get in touch with her past lives.

After two hours of meditation, she had finally succeeded. She was sitting in the lotus position, surrounded by swirling mist. Facing her with a warm smile was an old man wearing the robes and tattoos of an airbender. She recognized him as Avatar Aang, the previous incarnation of herself.

"Hello, Aang" Korra said with a hesitant sigh. "I... I could really use some advice right now."
"Indeed you could." Aang agreed, though his face suddenly became grim "But I fear that you might not like my advice."
"I will tell you of how Fire Lord Azulon invaded Omashu in the twelve-year-war," he continued with a heavy voice "And of the lesson I learned in that war."

"I was approaching my thirty-second birthday, when Azulon's comet appeared in the sky, greatly empowering all firebenders in the world. For years, tensions had been rising between Omashu and the Fire Nation. The Comet gave the Fire Nation an excellent opportunity to attack. Without question, I rushed to help the kingdom of my good friend Bumi, the crown prince of Omashu. Many young airbenders followed me into this war.

"By the time I arrived in Omashu, the comet had already passed and the Fire Nation controlled the city. I led my fellow airbenders and the earthbender resistance of Omashu to victory that day and Omashu was quickly retaken. At first, I believed that would be the end of it. But King Han, Bumi's father, demanded a retaliation against the Fire Nation.

"To my everlasting shame, I continued to take a side in that war for two years. The Fire Nation stubbornly fought back, despite my support for Omashu as the Avatar and despite how I convinced the Air Nomads to officially ally with Omashu.

"I finally saw how far from my duties I had strayed when the Fire Lord's grandson, Lu Ten was captured in battle. The soldiers of Omashu executed him in cold blood. All illusions I held about the war were shattered then. I fled to isolation here on the South Pole and meditated, hoping to find a better solution.

"The rest is history. The bitter war lasted for another ten years. The Fire Nation eventually won. Omashu became their colony. And I learned this lesson: The help of the Avatar is not always a solution. Some problems, people must solve for themselves."

"Wait..." Korra began, shocked by Aang's advice "That can't be right. You're wrong about this! I have to do something!"

Aang sighs in response "There is another story you could learn from. The story of Du-Bai-Se. Though I can only tell you of the beginning. I was not there for its' end. Du-Bai-Se was founded in a desert oasis by refugees and deserters from all sides of the twelve-year war. It was, perhaps, the only good thing to come out of that war. Benders from three nations working together to create a peaceful future.

"Over the next fifty years, Du-Bai-Se became what many thought would be the city of the future. The world capital of technology. The first great success was their ability to produce cheat quality glass. A combination of earth- and firebending in the production process. It was one of the best-kept secrets in the world at the time.

"The magnificent glass and steel towers of Du-Bai-Se have not been reproduced to this day. The next great inventions from the city were dragon oil and generators. I helped as much as I could in the early years after the war, but eventually I was asked to leave by the city council. I was not a particularly popular Avatar among the people of Du-Bai-Se, given how the entire city was born of my failures.

"It all came to an abrupt end a few years before my death. I was almost a hundred and thirty-one years old and Azulon's Comet was returning. The entire world was concerned that Fire Lord Ozai would follow in his father's footsteps and use the Comet to start a war.

"But the comet was not the only trouble in the world. A great sandstorm, greater than any in history, was descending on Du-Bai-Se. I offered to aid with the evacuation, but the city council insisted that no assistance was required.

"However, some assistance did go to Du-Bai-Se. The thirty-third battalion of the Fire Nation had been keeping peace in the Omashu colony under the leadership of General Iroh, the Fire Lord's older brother. The Fire Lord ordered Iroh to return to the Fire Nation, but Iroh defied that order and went to assist with the evacuation of Du-Bai-Se. The Thirty-Third followed him."

Aang made a long pause.

"And then what happened?" Korra blurts out after a few seconds of silence

"That is the story as far as I can tell you. You must go to Fire Lord Zuko to learn the rest. Tell him that I believe you have something to learn from the end of Du-Bai-Se."

Avatar Aang faded into darkness and the fog around Korra disappeared. She found herself back on the south pole, Naga huddled close to her. She felt numb in her limbs and tired. As a water tribe native, she quickly recognized the symptoms of hypothermia, and made good use of firebending to warm herself before heading back to the southern-tribe village.

Master Li's Lessons in Alternate History

Avatar Aang was the Air Avatar that succeeded Avatar Roku, born in 32 BAC (Before Azulon's Comet). His most famous, and infamous, act was his involvement in the twelve-year war between Omashu and the Fire Nation. His lack of neutrality did great harm to the credibility of the Avatar, but he nonetheless admitted his mistakes and attempted to make amends for them.

By 107 AAC, he was considered by many to be a wise and impartial Avatar, though sizable minorities in the Fire Nation and its' Omashu colony continued to hold his involvement in or his desertion from the twelve-year war against him.

He died in 107 AAC at age 139 and was succeeded by Avatar Korra of the Southern Water Tribe. Aang never married and has no known descendants.