Aang vs. Katara
One peaceful day in Republic City, Avatar Aang was walking down the street. As he was walking, he witnessed a mugging. He jumped in and tried to help the man getting mugged, but the mugger was getting away. He was quick so he evaded Aang quickly. Aang shot himself upward with a pillar of stone and saw the man escaping on the roof and he noticed how the mugger was a fire bender, as he levitated by using flames. Aang started to chase him. Aang remembered a waterbending trick that Katara taught him. Katara had learned this trick from Hama, the bloodbender. With a fluid wave he formed ice spikes on his hands and shot them at the pursing firebender. The mugger saw the spikes coming and created a wave of flames and then shot it at Aang, but he used firebending to cull it. He was catching up with the firebender when he noticed that there was a large rooftop garden and he again, remembered something Katara had shown him. He pulled the liquid from the plants and froze the firebenders feet, knocking him off the roof. He fell into a nearby stand and broke it. Aang told police what had happened and they arrested the man. “Nice work, Twinkle Toes” said Toph who was now the chief of police. “Thanks Toph!” said Aang. Aang then preceded home. He told Katara about happened. “It was amazing, I stopped him by---” “By what?” Katara asked. “Oh... It was nothing” “Come on Aang, You can tell me anything, we’re married now!” “Oh I just used a waterbending move that you taught me” said Aang. “And you didn’t want to tell me that? Why? said Katara. “Well... I...” “You’re embarrassed by that? And possibly that you’re a bender waterbender than me?” said Katara “Well... Wait, you think you’re a better waterbender than me? said Aang. “Of course, I do. I’ve spent years mastering one element while you’ve spent years mastering 3!” “Well, there’s only one way to decide that” said Aang. “A duel!” they both said! Aang, Katara and Toph arrive at the lake where Toph bended ten platforms around the lake for the duel. “Now, this duel is completely friendly and will end when either party is submerged for 3 seconds” said Toph. “The Avatar is only allowed to use waterbending. The duel will be three rounds. Are the duelers on their platforms?” Aang & Katara shook their heads. “Are the duelers on their platforms?” “Oh Sorry Toph, we are” “Go!!!” The duel commenced. Aang jumped off the platform where he used waterbender to jet among the lake. Katara shot her arms upward, and created ice spikes to knock Aang of his water jet. After a while of jetting around Katara finally got him but Aang saw this and jumped up on the spike and created a standing area. Aang was up high on his platform. Katara used his height to her advantage. She knocked out some of the tower and it started to fall. Aang quickly recovered. Katara quickly shot a jet of water at Aang while was falling. To dodge this, Aang recovered the missing ice from the platform and rose it again. used a water tornado to rise to Aang level. Katara jumped on the platform and augmented its size. She pulled water from the lake and shot a disc at Aang. He brought it behind, over his head and shot it back at her. She wasn’t ready and was knocked off the platform. To make sure, Aang jumped up and came down hard, knocking the whole tower over. But because of this Katara was knocked to one of the platform. After she recovered, Katara noticed Aang recovering. She acted quickly by creating two octopus arms and shooting the water at Aang. But by the time this was going one, Aang had recovered and he was on his water jet again. Katara shot water jets from both ends and knocked Aang into the water. Toph gave round one to Katara. Both of them were on their platforms when the round began. Aang jumped on a smaller ice platform that only he could fit on. He attempted to make a dome over Katara, but she used the dome water knock Aang off. She missed as he was still rising. Katara jumped on an ice board and attempted to created a whirlpool. She was successful. Aang’s platform started to crumble as he jumped off. He then dove underwater for 1 second and came up with water spout. They were both on waterspouts as they both shot beams of water at the other. They did this for a while. Katara turned one of the beams into a giant spike. Aang fell after being hit with it and flew back into the water. “3....2....” Aang shot out of the water with incredible speed and shot dozens of ice-disks at Katara. It was too many for her and she fell into the water. Aang won the round. “Well Aang, you’ve done quite well. Your waterbending master is impressed. But I have a few tricks up my sleeve.” Round three started. Katara rose a column of ice that blocked Aangs water jets. She rose another, and another, and another column and stroke them. They fell and Aang did everything he could to break them. He shot many water blades and sliced a thin section that missed him. The remaining ice columns made a bridge from platform to platform. Katara formed octopus arms and ran across the bridge. Aang sliced the bridge in half and then Katara used one of her octopus arms to create running point with them. She ran to a different platform. She made a sizable wave and launched it at him. He managed to send it back at her from the top. The rest of the wave died back into the water. They were both evenly matched. And then... It started to rain. And then Katara remembered something. Katara stuck her arms out and Aang noticed what she was doing. He used a water whip to grab her arms and he pulled them. She lost her balance and the rain she was gathering began to fall. The excess water fell and knocked them both on to their water jets. Katara had begun to chase Aang, making water spikes pop up everywhere. Aang shot some ice spikes at Katara, making her stop her ice pillars. Aang retreated to a nearby platform, as did Katara. Katara struck the water with her hands and started to make a jet . She kept on making them and eventually the platform Aang was on broke and collapsed. As did Aang. He quickly recovered, but Katara caught this and shot a jet of water at him. He flew a while and Katara made an iceberg surrounding him and submerged it in the water. Katara won the duel! “And the winner is Katara!” said Toph. “Well Katara, I’m impressed. You are a better waterbender than me.” “Thanks Aang!” she said. “But...” he said. “But... What?” She formed ice spikes and pinned him to a tree. “But, Nothing” Aang said.
So that was just a little fanfiction I made up. This is obviously noncannon but it's fun to read, so enjoy it!