Aang had been here, for what seemed like forever. Sometimes he heard the pained cries of his friends as they were subjected to the same treatment as he was. This prison was designed to keep Aang forever.
Zhao told him they would keep him alive... barely. Aang lay on the cold stone metal in his tiny prison cell. He tried to not breathe in the stink of waste and mould.
Sometimes the guards dragged him around the jail, with broken legs so he could not run. At those times, the guards made sure Aang saw his friends being beaten, or worse. Katara, Toph, those two had been treated the worst of all his friends. Zhao liked to let the guards do whatever they wanted with them. Once, Aang met Katara's eyes, and he realised she had been broken again and again.
His throat constantly cried out for water, but he would never be trusted with some alone. He was still the Avatar, after all.
Aang could barely move his limbs, they were red and scorched, still broken in some places. The Fire Nation did not care, this meant he could not bend or escape. He lifted his hand up high enough to scratch a vertical line on the wall, next to dozens of other tally lines, counting the days he had been in this cell.
He felt a tear slide down his swolen cheek as he let his arm flop back on the ground. We will keep you alive... barely. Zhao's voice echoed in his head, all these months after hearing it last. After all, we can't have you dying, because you'll just be reincarnated, and the Fire Nation will have to begin it's search all over again. An idea began to seep into Aang mind.
Escape.
The idea ran round and round his head, filling him up, promising him things he had desired for months. Slowly, he forced himself up, and with all his might, he ran against the metal wall, head first. There was a loud clang! but Aang did not care, no-one would come running. The only time he saw another human was when they came in to give him one of his two tiny meals a day, or when they came to beat him.
Aang now felt blood trickle down his forehead, and patter on the floor. His head started to feel light and dizzy when Aang rammed his head against the wall for the third time. On the forth time his featured were obscured by the blood from his forehead wound.
For the fifth and final time he ran against the wall. His skull cracked open, and still no-one came running.
As Aang began to black out, he felt as if he were falling. He saw his friends, Katara, Sokka, Zuko and Toph, out of the corner of his eye as the sky rushed past him. He let gravity take him, and when he hit the earth, Aang was gone. At the last second, he saw himself be reborn, somewhere in the Northern Water Tribe.
And so, Avatar Aang died with a smile on his face as he realised he had finally escaped this prison.