"What are you doing!?"
Zuko practically turned on his heels, more surprised and frightened than Azula had ever made him before. Sure, Zuko always got scared when Azula's prowess grew even further while his stayed the same, or when she committed one of her 'harmless' pranks, or when she told another lie about him to father. But this time, it was different. The feeling you get when you're caught with your hand in the cookie jar at midnight. When you had actually done something wrong.
Except in this case, the jar was Azula's wardrobe. And the cookies, well...
They were her clothes.
Had the young Fire Prince had his wits about him, he may have remarked on how his usually cutting sister was just as speechless as he was. No remarks about him being a girl, no threats to reveal his crime against dignity to mother or father. No attempts to extort the latest favorable 'deal'. A rare expression for her: shock.
"Azula, I..." he finally stuttered a response. He wanted to run. But with his state of dress, where would he run? Out there, everyone could see him. Everyone would know. Father would know.
He was a deercat in the firelight. Paralyzed by indecision.
Zuko could see that formulating look in her eyes. The slow and methodical march, the Fire Princess's resurgence of control. Decisions always seemed to come easy to her, even the hard ones.
He had to say something. Azula, she'd... she would...
"Don't tell. Please." at least she could keep a secret, even if there was always a price.
He looked ridiculous. The clothes he was wearing didn't fit him - at least a couple sizes two small. His hair down, but Zuko hadn't bothered to brush out the kink created by that ridiculous pony tail of his - and perhaps the poorest use of lipstick Azula had ever seen. Had the she engineered this scenario, she might have thought it funny. She'd always known little zu-zu to be a deviant. The weird one. Always falling behind in his training, his learning. Never seeming to fit in.
This however, was far too depraved to be a laughing matter. Though the Fire Princess had resumed her illusion of control, her insides were still churning about... wondering. The scenario before her was truly alien - as if one of her teachers at the academy had asked a trick question, leaving out one vitally important detail. One could work out the inklings of an answer, but without the rest of the context you were stuck, unable figure out the rest.
"I won't." Azula finally assured.
A sigh of relief from Zuko.
"...if you tell me what in the name of Agni you're doing" she crossed her arms.
"Well, I..."
The boy stuttered, his heart racing, not even sure what he wanted to say. Should he tell the truth? Would Azula even believe him? ...what even is the truth?, he finally thought, all of his prior confidence that he had mustered for this occasion having evaporated upon his sister's arrival. Assumptions, conclusions that once seemed stubborn as rock now flowing free like water.
It was simply too much for the young boy to put into words. But he had to put it into words or else she would do it for him.
Pervert.
It was a bad decision. Zuko should have just stayed in his room, curling in the covers as his jealousies, insecurities, failings and emotions washed away into an early sleep. Surely that would have been preferable than dragging them into the spotlight like this. Anything else.
He had just wanted to.
Zuko looked at Azula - or at least in her general direction - his gaze shifting up from the floor he had been staring at for the last eternity.
"I wanted to look like you." he finally admitted.
He cringed, regretting the words as soon as he spoke them. Zuko may as well have castrated himself. Though at the same time, he meant every word - making the admission ever the more troubling. He had put himself at the mercy of Azula's court, pled guilty by giving her a damning confession.
And she laughed.
Nay, the Fire Princess was in hysterics, giggling like her friend Ty Lee (of whom Zuko also harbored jealousy, though that would be much harder to get him to admit).
Azula almost didn't believe him. It sounded like the punchline to a joke rather than something that was actually real. "...you wanted to look like me!?" she asked.
"...Y-Yes!" he affirmed. "Stop laughing!"
It was futile however. This was just the latest in a string of copy-parrotcats done by Zuko, each one making his sister laugh more than the last as he failed to emulate her.
To be as good as her.
"Zuko, you're just as pathetic as a girl as you are a firebender." Azula said pointedly, matter-of-factly - no longer laughing.
Zuko looked down at the ground, crushed without even really knowing why. Why should a boy feel bad about not being a girl? It didn't make any sense. And even if it did, he could hardly deny her claim. Zuko didn't need to look into the mirror to know he looked downright silly. He had no clue what he was doing. He was pathetic.
The boy pinched himself, hoping to become lucid, to wake up from this nightmare. He couldn't even bear to keep his eyes open anymore. He didn't want to see himself, to see his sister. To see the way she looked down on him.
"...are you crying?" he heard her say.
Zuko was too far gone to witness all hints of humor drop from his sister's face. Though she often took opportunities to humiliate or otherwise disparage her brother, she never sought to bring any harm to him. Even though weak zu-zu and her would likely disagree on the definition of 'harm', this was definitely not on Azula's agenda. There was no benefit, no gain in her brother being broken like this. It wasn't even fun, it was like beating Ty Lee at a game of Pai Sho. And if she were to show her father this shameful display...?
He would be put in a black box and hidden away forever so that the public never learned of the (likely former) Crown Prince's deviant tendencies.
They were brother and sister. Though Azula certainly wanted to prevent her brother from unjustly reaping the benefits of being firstborn despite his obviously inadequate ability, the line had to be drawn somewhere. It simply wasn't... honorable? Or something. Stupidly cruel, even by her standards.
"Zuko."
He didn't hear her in between his sobs. Zuko hadn't cried like this since Father had said something or other about being lucky to be born.
Azula had been rooted in her spot at the doorway, unable to approach the abomination that was her crossdressing brother. But she found it in her to move forwards.
"Zuko." she repeated her brother's name, a hand on his shoulder. The boy opened his eyes. "Look... I-" she paused, not used to speaking so. "-I won't tell. I'll leave while you dress yourself in something proper. Just be gone by the time I get back."
The boy nodded slowly, waiting for his sister to leave and all traces of his escapade to be erased before finally assuming his walk of shame back to his room.