Just a quick note so you don't get confused, I'm starting this story halfway through Sozin's comet: Part 4: Book 3, it'll make more sense to the story later, but some parts will be different. I haven't written a fanfiction before and i doubt my grammar is amazing but bare with it!

Enjoy the story! :)

"No, I'm not going to end it like this" Aang stated firmly, looking over his shoulder and the defeated Fire Lord.
"Even with all the power in the world, you are still weak" Ozai hissed before getting to his knees to attempt to punch a ball of fire at Aang.

Aang sensed his movements through his earth bending that his friend Toph had taught him. As Ozai ran at him, he leaned forward and kicked up an earth pillar to redirect Ozai's fire blast, locking his hand in it he ran around the other side of him and locked his hand in another pillar, he put his hands up to the sky and with a swift movement brought his arms down, pulling Ozai to his knees with him. He frowned and looked into the Fire Lords eyes and saw the fear and hate that consumed him. He leant in and pressed his thumb to his forehead and shut his eyes, remembering the words of the lion turtle.

"In the era before the Avatar, we bent not the elements, but the energy within ourselves"

As his eyes opened a blue glow shot out of his eyes and mouth, he felt the power of his past lives raging inside him, moments later an orange glow shot out of Ozai. Aang felt all his hatred consume him as his body began to glow orange.

"To bend another's energy, your own spirit must be unbendable, or you will be corrupted and destroyed".

He could feel his own soul beginning to slip away bit by bit. He was losing. Then a thought of Katara entered his mind, those ocean blue eyes that he could not seem to forget. He knew if he wanted to win this, he would have to put her behind him, he was the Avatar after all. 'I'm sorry Katara'.
He had responsibilities he was destined to accomplish since the day he was born, he couldn't be selfish and put his desires first. As soon as he came to this realisation, he felt more powerful and had overcome Ozai. He turned blue and a massive beam of light shot through the air. Aang weakly stumbled as Ozai fell to the floor.

"What" he groaned "what did you do to me?"

"I took away your firebending" Aang said "You can't use it to hurt or threaten anyone else ever again." He walked to the cliffs edge, took a deep breath and activated his avatar state before bending the ocean to defuse all the fires around causing catastrophe. The lands surrounding him were smoking and reduced to mostly ash. It was upsetting to him since the monks had taught him that all life was sacred.
He looked to the sky and saw a Fireship approaching. He didn't care if they took him now, the Fire Lord was gone, however he did feel weaker now than he ever had before. His knees collapsed and his body fell to the floor with a thud, his head hitting the rock floor. It felt as if someone was smacking his glider over his head over and over. He could hear voices calling his name

"Aang?"

They got louder and louder. "AANG!". One voice stood out to him the most as if it was calling him back to her. The last thing he saw was the world fade to black.

When Katara had seen Aang unconscious on the ground she panicked, she didn't realise that fighting Ozai would take this much of a toll on his body. She knelt beside him and cradled his head in her lap trying to make him more comfortable. She examined his body closely and noticed he had cuts everywhere, there was a very prominent one on his left cheek that she knew would eventually scar and a substantial amount of bruising on his left rib.

"Sokka, help me get him up" she ordered. She was mothering Aang, as usual. She did it to everyone when someone was hurt, or when something needed to be done.
Sokka shot over and helped his sister get him up. They both had an arm draped over their shoulders and carried him into the Fireship.
They went straight to the bed quarters and put him in the first room they found.

"Sokka I need you to get me a bucket of water" She ordered, "Suki some clean bandages and cloths". The couple bolted out the room, doing what they were told. They didn't dare cross Katara when she was like this. When it came to help Aang there was no messing about. He wasn't just the Avatar to her, but someone she had deep feelings for. Her heart ached for him. It upset her seeing him like this; so weak and fragile. He was normally so strong and not much used to bring him down like this. The only time she can remember was when Azula had shot him with lightning.
She was too busy ordering everyone around to notice a fair amount of blood dripping from his ears. His body had broken out into a sweat, dampening all the bed sheets.
Suki came running in with the assorted cloths and bandages, setting them on the table aside from the bed.

"SOKKA!" She yelled "WHERE'S THAT WATER?".

She was furious, she couldn't believe her brother was taking this long just to get water. She took one of the clothes Suki had gotten her and started patting his body dry. She was too busy to even notice that Sokka had come in and placed the bucked on the floor. She wet one of the clothes and squeezed majority of the water out before putting it on his head, attempting to bring down his body temperature.

After hours of vigorous healing sessions on his bloody and bruised body, she as exhausted. His temperature had come down and his ears were no longer bleeding, but there wasn't much she could do about his bruised ribs. They weren't broken but she did conclude they were fractured. The last thing she did was wrap up all the wounds to prevent further bleeding and to hold everything right where it's meant to be.
She wiped the sweat off her face and looked at the young monk. He was finally sleeping peacefully. She had noticed that while they were travelling, he had been growing up, especially after being struck with lightning. That night something in him clicked and he wasn't as goofy as he used to be. She missed that, but when he was asleep, he looked like that same goofy kid she found in the iceberg. She got up and left the room to find the others. She found them all in the dining area. Sokka as usual was shovelling food into his mouth and Suki was just looking at him like he had a serious problem.

"What? You should be used to it by now" He said with a mouth full of food. He looked up and saw Katara leaning on the door frame.

"Katara hey!" he smiled "We would've waited for you, but we didn't know how long you'd take... and I was starving"

Katara couldn't help but laugh at her brother. How typical.
"It's okay, I'm not that hungry". She walked over to the two and sat down with them. The rest of the night was less stressful then their day had been. They told each other stories and had lots to laugh about, but all Katara could think about was Aang. She was finally ready to tell him how she felt, but she didn't know how to. She just hoped he still felt the same way.