Katara wasn't staring, she was merely observing the earthbending training as an outsider concerned for Aang's welfare. She definitely wasn't noticing how Aang's forearms would bulge when he strained to shove a stone in Toph's direction. If she did perhaps note how the blue lines racing down his arms accentuated his muscles, it was just from curiosity. Aang didn't like talking about his airbending training that much, and Katara was interested to know more about his culture. That is all there was to it.
There wasn't a cloud in the sky, and the bright sun reflected off of Aang's clean-shaven head. Growing up in the Southern Water Tribe, Katara was used to men growing their hair out. When Sokka let his hair down, it almost reached his shoulders, and in their tribe, that was considered short. It was the difference of aesthetics that caught Katara's attention, and nothing else. She wasn't observing how his pale skin contrasted nicely to his blue tattoos, or how his gray eyes would twinkle every time Toph noted he got a form or move correctly.
If Katara were to notice these things, it would mean that she was staring, and she definitely was not staring. Aang was her best friend. They had laughed together and they had cried together. They had even faced death and had come out on top. He knew all her secrets, and she knew all of his. There was nothing that could ruin the relationship between them because they were strictly best friends. Katara would keep repeating that fact to herself until the end of time.
She would be lying to say if no other thoughts had crossed her mind, but Aang was only twelve. Even though he wasn't much younger than her, he was still a kid. Not only was he a child, but he was also the avatar. He had to shoulder the responsibility of the entire world, which is why Katara would always support him and be by his side – as his best friend.
Katara began tugging at the end of her braid, unwinding and rewinding the few bottom inches. If it weren't for those nomads they had met on the way to Omashu, everything would still be normal. Of course, their group had to get separated in the cave, because nothing was ever easy for their little family. Aang and Katara had wandered aimlessly, not finding any clue to a sort of exit, when Katara said something stupid. She said that they should kiss.
Katara could feel her face heating up just with the memory. Of course Aang hadn't wanted to kiss her – he just saw her as a friend! Their awkward interlude could have been the end, and then Katara wouldn't be left with all this chaos swirling inside her mind like a hurricane. Unfortunately, things did not stop there. The pair had been getting desperate and their light had been fading. They had done the only logical thing in that situation – they kissed.
Why couldn't it have been the Cave of Two Platonic Friends? Perhaps they could have figured out the riddle much faster that way, and gotten out without any further thought on the matter. Instead, they had kissed, and Katara immediately ran away afterwards, citing the excuse of wanted to leave the cave.
Aang never brought up the incident again. Obviously, he didn't think much of it otherwise they would have talked. Aang had never been shy to speak to Katara about anything. It had meant nothing to Aang, and their friendship continued, so why couldn't she stop thinking about it? Katara kept thinking about how Aang had to rock up slightly on his toes to reach her lips. She thought about how Aang's lips had been slightly chapped, but not rough. Her hands tingled when she thought about how their fingers threaded together during their short, but perfect, kiss.
"Hey, Katara!" Aang suddenly popped up in front of Katara, wide-eyed and beaming at her so brightly, that it almost hurt to look at. "What are you thinking about?"
"Um," she stuttered, "basket weaving?"
"Neat," Aang replied earnestly. Katara inwardly sighed in relief. Aang obviously felt none of the tension that was plaguing her. She knew she had to let it go. "Toph released me from earthbending practice. Want to get some waterbending training in?"
"Sure!" Katara was happy to have a distraction from her traitorous thoughts. That was before, however, Aang stripped off his shirt.
Katara had laid eyes on Aang's bare chest before. He was not modest about his body, and practicing waterbending was easier when you weren't laden down with sodden clothes, but her eyes couldn't help trace the lines his sleek muscles formed. She knew that once he got older and filled out a bit more, his body would rival any man's.
When she had finally realized her eyes were tracking his movements like a cat hunting its prey, she immediately shot her gaze back to Aang's face. To her surprise, he was blushing, rubbing the back of his head sheepishly. If she wasn't mistaken, it almost looked like Aang was using that movement to flex his biceps.
Quickly stripping off her outer clothes, until she was left in her bindings, she immediately grabbed his hand and dragged him over to the water's edge. Gritting her teeth, Katara's hands curled around his shoulders to keep the airbender in place. Standing on the edge of the bank, she maneuvered her body to stand behind his, guiltily taking in the pleasure in feeling the warmth of his back.
"I've noticed that lately your left side drops when you go in for an attack with your right. I know you are right-handed, but if you let your left side go weak, you won't be prepared if someone decides to strike there while you're attacking with your right." Katara's fingers trickled up the blue line caressing the skin of his left arm as she elevated it in place. She let out a deep breath to steady herself, and continued her lesson.
Several yards from the bank, Toph completely flattened her feet when she felt an irregularity in Aang's heartbeat. His heart had sped up to such a rapid speed, that she immediately grew concerned. Her feet shifted into a wider stance, and laughing to herself, she immediately noticed what was going on.
Katara and Twinkle Toes had practically melded together on the water's shore. Toph was honestly surprised Aang hadn't combusted from their close vicinity. As she was new to the group, Toph hadn't quite gotten down the dynamics yet. Every time Aang and Katara got close to each other, their hearts sped up, and their posture stiffened. She wasn't exactly sure what was going on, and before she could continue her exploration further, the two had jumped into the water, completely blocking off her sight.
"Hey Boomerang Boy!" Toph called out. Sokka looked up from where he had been napping and then frowned at the nickname. "How long has that been going on?"
"How long has what been going on?" Toph indicated the pair, no longer spending time practicing their waterbending forms, but rather splashing each other with small waves of water. They were both giggling, and Toph doubted she had ever heard Katara sounding so relaxed.
Sokka narrowed his eyes as he examined the airbender and his sister. They had always been close. They had been best friends ever since the moment Katara cracked Aang out of his frozen tomb. The two of them gravitated towards each other, touching constantly. Sokka always thought of the two of them as tactile people, but when he thought about it, the solo hugs the two engaged in without Sokka did seem excessive. Even now, as Sokka watched them from a safe distance, Aang snuck around behind Katara to tickle her underneath her ribs.
Sokka's eyes bulged out of his head, and his mouth dropped so low, that his chin practically touched his chest. "Aang likes my sister!"
"Well, duh," Toph nudged Sokka with her foot. She earthbended a small stump next to Sokka to sit upon. "But are they dating?"
"No!" Sokka yelled so loud that he caught the attention of the two in the water. Aang and Katara's heads both shot up, and they immediately fell into a defensive stance. "Uh, I mean, no Momo! You can't eat that!"
Aang and Katara both rolled their eyes, so in sync, that Sokka would swear that they choreographed that move, before going back to their play.
"So, Aang and Katara, huh?"
"Well," Sokka shrugged, "she could do worse.