Last Time
The first time Zuko saw his farther after his banishment was the last time. It was all part of the larger plan really. Sokka had made the details quite simple, and Zuko had to admit, the plan was close to flawless. All he had to do was slip into the palace as a servant and wait. Wait until nightfall when Aang and Sokka joined him. Wait until Katara and Toph had taken up their positions at the main gate to cause a distraction. Wait until everything was perfect. Then they would strike. But the attack was not when Zuko saw his father.
It was on his way to the palace, face shrouded by the large brimmed hat. His father had been strolling out in the city, surrounded only by two bored looking guards. Zuko had frozen as he recognized the face of his father, his tormentor, his idol. He hadn't been able to move, fear sweeping through his body, memories of a fiery punch and burning ticking through his mind. His father's face had aged, wrinkles lining his eyes and corners of his mouth, and his eyes were different than Zuko remembered. Sadder and yet more cruel than before.
Zuko knew he had changed too. He was taller now, sturdy and strong. His face was leaner, and his eyes had become calculating and sure. He wasn't Prince Zuko anymore. He was just Zuko, accomplice of the Avatar and plotter of his own father's death.
Zuko wondered through the haze of fear in his mind whether, in the midst of his father recognizing him, Ozai would realized how much Zuko had changed. If maybe, as he watched the execution of his own son, he would casually address the aristocrat sitting next to him and comment on how Zuko had grown up over the years. Maybe later in his chambers, he would regret banishing his son and wished he had kept him on to help win the war.
His father passed him, eyes sweeping over Zuko once, and then passing on to other people in the busy street. He hadn't recognized his son at all. Zuko watched him go, and then turned, holding back the tears, and pushed on toward the palace.
Five hours later, Lord Ozai of the Fire Nation was dead.