A/N: So I've never written for Avatar before, but I thought of this today and I just had to write it down. The premise comes from (and borrows some lines from) a scene in an early episode of the anime Code Geass, where Nunnally shows Lelouch how a pinkie swear works, and I thought it was a really sweet little sibling moment they had there.

For some reason, it made me think of Zuko and Azula, even though their relationship is NOTHING like Lelouch and Nunnally's, but I digress.

One last thing, Azula is very OOC in this fic, but since it's really the product of her mental breakdown, I figure it's okay.

**

There was once a time, when Zuko and Azula were but five and three respectively, a time before their firebending skills became apparent, a time before all the corrution, the lies, the atroicites. A simpler time when little Azula's eyes would brighten every time her brother came into the room. When the siblings would play in the courtyard together for hours, and every night before bed, Azula would hug her brother close just before the nursemaids carried her to her room. It was a happier time for everyone, but now it was over.

Now, twenty years later, Fire Lord Zuko makes his monthly trip to the isolated island just outside the Fire Nation. Zuko stares straight ahead, his mouth set in a firm line. He only moves when the ship captain comes to announce that they have arrived, and then he only nods in acknowledgement before disembarking.

The facility is just by the coastline so Zuko only has to walk a short way to reach it. When he does the nurses all bow to him. They have done this a million times and it has become routine. He walks past them down the hall to a metal door at the very end.

Before entering, he stops to listen. He hears humming, and knows she is awake; likely waiting for him to arrive just as she's done so many times before.

Zuko finally grasps the door handle and lets himself inside. He is met by the sight of her sitting on the ground with her back turned, her knees drawn up to her chest as she plays quietly with the doll he brought her last time.

"Azula." Is all he has to say for her to turn her head and look at him.

Her eyes widen and a large smile appears on her face. It is not one filled with the hate and cruelty Zuko once knew, but instead one of child-like excitement and glee. Before Zuko knows it, she is clinging to him, her frail arms keeping him in a surprisingly strong grip.

"Zuko! You came to see me!" She cries out happily, "I've missed you so much big brother."

Zuko smiles for her and pats her head, "So have I Azula, tell me, how are you?"

"Oh I'm wonderful, Zuko." She answers, finally letting him go, "Everyone here is so nice to me! Oh, and guess what?"

"What?" Zuko plays along.

"Last week, during art class, I drew a picture and Miss Aya said it was beautiful and it was the best she'd seen all day!" Azula cheers, dragging the word 'all' and spreading her arms wide to further emphasize her point.

Zuko's smile grow larger at this, "Oh really?"

Azula nods eagerly, "Oh yes, do you want to see it? I have it right here!"

And she darts toward the small chest of possession the hospital staff lets her keep. She rummages around a little and then pulls out a scroll and quickly runs back to him.

Zuko takes the scroll and unfurls it to reveal Azula's drawing. He stares hard at it, his expression unreadable, and soon Azula grows impatient with his silence.

"See? That's you right there, and that's me." She explains, pointing to the respective figures on the paper.

Zuko nods, careful to keep from showing emotion, "I see, it's lovely Azula."

She grins, "You know why I'm smiling in the picture?"

He shakes his head.

"Because I'm with you big brother!" She says with a giggle.

Zuko bites down hard on his lip.

**

"Zuko look! Turtle ducks!"

"Yes, I see them."

"Come on, Miss Aya gave me some breadcrumbs, let's go feed them!"

As Azula runs towards the little pond in the hospital courtyard, Zuko walks slowly behind her. He reaches the pond and silently watches as she throws the crumbs to the small animals and giggles every time they swim toward them.

"Aren't they cute Zuko?" Azula gushes.

"Yes they are." Zuko agrees, "And I think that one likes you."

Azula looks down to see a lone turtle duck swimming near her hand. Tentatively, the former Princess reaches out and scoops the tiny creature into her hand. Zuko can't help but think back to a time when the turtle ducks fled from girl before him, but quickly brushes those thoughts aside.

"Aw, he's adorable, isn't he?" She holds the turtle duck out to him.

Zuko smiles, "How do you know he's a 'he'?"

Azula blinks, then pouts childishly, "Don't be so mean Zuko."

"I'm sorry," He answers, wrapping his arm around her shoulder, "I didn't mean to upset you."

For a moment, she refuses to make eye contact, but then she sighs and returns her gaze to him; her smile is back.

"Okay Zuko, I forgive you."

Zuko only pulls her closer. As he does this, the turtle duck begins to whimper softly.

"What's wrong little guy?" Azula asks it with concern.

"I think he wants to go back into the water now Azula."

She looks for a second as if she may cry, but only frowns and reluctantly lowers her hand into the water, allowing the turtle duck to swim away.

"Bye bye." Azula says sadly.

The siblings watch as the turtle duck swims to the middle of the pool and both are surprised when a slightly larger turtle duck meets the baby. Azula grins.

"Look Zuko, that must be his mother." She points at the two animals.

"Mmm." Zuko answers.

"Mother was here before," Azula continues, "Our Mother that is, she came last week."

"I know," Zuko replies, "She told me. She said you were looking well."

"We had lots of fun together!" Azula begins to say, "We picked flowers and played with my dolls and everything!"

"I'm glad you had fun." Zuko says.

"I did, but can I tell you a secret Zuko?" Her voice drops to a whisper, "I like it best when you come."

**

They spend the day together, playing and talking and enjoying each others company for the short time they have. The only time they are apart is for trips to the restroom and when Zuko briefly leaves to talk with Aya, Azula's head nurse.

The two stand in the hall outside Azula's room, the door shut and locked so she can't hear what they are discussing.

"How has she been?" Zuko asks.

"Well, as you can see My Lord, she has remained fairly stable these last few years. There have been no more episodes, and she hasn't lost her temper." Aya explains.

"And her firebending?"

"It hasn't returned." She shakes her head, "Sometimes, she makes little sparks but…"

Zuko nods, "I see."

Silence.

"Do the doctors know when she can get out of here?"

Aya frowns, "Well, to be honest, they aren't sure if she can be released. Her memories of her life after early childhood have all but vanished, and you've said it yourself many times that we can provide the best care possible for her."

Zuko's eyes have by now moved away from the black haired woman and are resting on the door's small window, where Azula can be seen coloring with a big happy smile on her face.

"Yes, I know."

Aya knows her Fire Lord is unhappy with this no matter what he says, and so she offers him a comforting smile. "But you know, there's always a chance she'll go back to normal, and you can take her home again."

"I suppose," Zuko says with a small nod.

But what was normal for Azula?

**

"Do you really have to go?" Azula whines.

"I know, I don't want to leave you either." Zuko says, using a finger to wipe away his little sisters tears, "But I'll be back next month you know."

"Will you bring Ren?" She asks, looking up at his face.

Zuko frowns at the mention of his four year old son. He has told her many times what he looks like, how much he's grown and she loves hearing about her nephew. However, both Zuko and his wife agree that Ren is far too young to be brought to a mental health ward.

Still, Zuko can't bear to say no to Azula, so instead he clears his throat and says,

"We'll see what happens."

This seems to satisfy her a little, however Zuko knows that she will continue to ask every time he comes.

"My Lord," The ship's captain calls over to him, "We must go now."

Azula hangs her head at this, "I'll miss you so much big brother."

Zuko stands still for a moment, then he wraps his arms around her and lightly kisses her on the forehead.

"I know, but I promise you Azula, I'll be back before you know it."

Through her tears, she smiles that innocent little smile that breaks Zuko's heart a little more every time he sees it. She pulls away from him and takes his hand in hers, hooking his pinky finger together with her own. Zuko blinks in confusion.

"What's this?" He asks.

"It's a pinkie promise," Azula grins, "Miss Aya taught me."

She then slowly sways their wrists back and forth and sings:

"Cross my heart, hope to die, eat a thousand needles if I lie, pinkie promise song!" She releases his finger on the last word and giggles.

Zuko grins back now, "Well that's scary, I may have to eat a thousand needles someday."

"That's right!" Azula cheerfully answers, "So you better keep you promise and come back soon."

"Don't worry Azula, I would never break a promise to you."

Zuko reaches out to brush a stray piece of hair behind her ear, "I love you Azula."

"I love you too Zuko."

**

There was once a time when Zuko and Azula were children where they loved each other dearly. Those times were over.

As Zuko sails away on his ship, he waits until the island is completely out of view to fall to his knees and let out a sob. The crew is not alarmed by this, it happens every time, and they know when the Fire Lord returns to the palace, he and the Fire Lady will adjorn to their chambers and he will cry in her arms while she whispers comforting words into his ear.

He will cry for his sister's lost future, for her destroyed mental being, and for all the horrible deeds she commited that had consumed her in the end.

He will cry for the little sister, the friend that he lost.

**

A/N: So how do you like it? Please review and tell me.

And for those who are curious about Zuko's wife, I am leaving that for the reader to decide.

Ciao!