If you love something, set it free.

The first time Kairi hears those words, she's too young to understand.

She's just a little girl, and she's running, running because nothing could ever slow her down. Like lightning she's at her grandmother's feet, fiery hair wild and smiling like the sun, because in a glass jar in her tiny hands there is a butterfly. And it's blue and green and every colour in between and she has named it Zazu. It is hers, and she'll keep it safe forever.

She expects Granny to be proud. She expects a warm smile and an enveloping hug as she's told how clever she is. But she's left cold. Her grandmother is just gazing sadly at the trembling wings that glimmer like dusty silk. Butterflies aren't meant to be kept in cages, she says. They need to fly free on the wind. And Kairi's suddenly drenched with despair, because she loves Zazu - she does! She'd never hurt it! She only wants to protect it.

But she's helpless to stop Granny as the jar is pulled gently from between her fingers. All she can do is watch as the fragile wings unfurl and Zazu flies through the window and away over the garden.

Tears flow freely and Kairi will never, never speak to her grandmother again. Zazu was her friend and now it's gone forever and it's never coming back!

And Granny just smiles a little, and pulls Kairi up onto her knee. She wipes the tears away and murmurs those words like a joyless song.

"If you really love it, you have to set it free."

And while Kairi thinks that's stupid, and it doesn't make sense at all, she starts to get the golden dawning feeling that maybe she's done the right thing.

If it comes back, it's yours.

She's older now, and much wiser. She thinks that maybe the saying makes sense after all. Except now there are no butterflies, no birds and no small wild animals. There is only Sora. Sora, who has always wanted adventure and something much larger than this provincial life. Sora, who has the wandering soul of a gypsy.

He doesn't belong in a cage either.

But she loves him. And her greatest fear is that she'll lose him again, and that this time he might not come back to her. So she's been selfish. She's locked him away where the walls are so much more impenetrable than gilt or glass or stone ever could be.

As soon as he is back, she corrals him. Like a wild horse cornered, fear and unrest spark an edge in his eyes. But he can't say no. All Sora has ever wanted is to make his friends happy. He would sacrifice everything - though, of course, this is no sacrifice. They are friends, and this is the logical next step.

She tries to be a good girlfriend. She holds his hand and plays with the insanity he calls his hair. She bats ebony lashes and giggles and smiles just for him. They see movies and they sit next to each other in class and they spend long, lazy hours just lying on the beach.

She keeps him happy. She moulds herself around him like the waves roll around rocks on the shore. And while she does, she keeps him safe. Because she needs him. She can't lose him, and she won't.

It sounds like it should be hard. But really, their relationship is so easy. And when they are lip to lip, when his hands touch her skin, she is more alive than she can ever remember being.

Every act, every scene, they play their roles to perfection.

The only time his eyes flicker far away is when Riku is near. And that's fair. That's Riku. Tall and aloof with quirking eyebrows and teasing eyes and the only smirk in the world that can even be seen through a curtain of icy hair. Sora's best friend.

Riku is Riku, and he's important to Sora. So even when Sora's too far away to catch, when he's with Riku, she knows she doesn't have anything to worry about.

If it doesn't, it never was.

They're having a boys' night. She suggested it herself, picturing games and contests and boy talk, whatever that entails.

She doesn't mean to intrude. Honestly, she doesn't. But Sora, a veritable legend of forgetfulness, has left half his schoolbooks at her house. She only means to return them. So she slips quietly into Sora's home.

Sora's mother is quite possibly the friendliest woman on the islands. And she knows, in the way all mothers probably do, that Kairi loves her son. And so she is known to shanghai Kairi at every possible opportunity to bubble and gush and indulge her only son's girlfriend. But even as she does, Kairi can sometimes catch something flickering behind the older woman's eyes. Something sad and wistful and almost pitying. And Kairi doesn't like it at all.

So she sidles unnoticed past the kitchen, wherein Sora's mother is humming contentedly to herself, and tip-toes her way up the stairs and down the hall. Sora's door is all but closed, and she is a split second from pushing it open when suddenly her mind is filled with angry red slashes. NONONO. Naminé does not think it is a good idea. And her Nobody is never normally so insistent. So Kairi listens, leaning in to the door ajar and peering through instead.

What she sees makes her crumple inside. The two boys are standing in the middle of the room. One of Riku's arms circles her boyfriend, hand resting lightly between his shoulder blades. Sora has his head bowed, lying against Riku's chest. Kairi doesn't know where the thought comes from, or even how she can think at all, but she fancies that he is listening to the drumming rhythm of Riku's heart. The heart that Sora himself returned.

Oh.

For an instant, she tries in vain to pretend that it is innocent. Then Sora whispers, and Kairi, straining to hear, feels her hope dissolve into the suddenly too-hot air.

"I need you, Riku."

At the words, Riku tightens his grip. Flexing his fingers against Sora's skin, he somehow manages to pull the boy even closer as he buries his face in the mane before him. When they come, his words are muffled and broken.

"I'll always be here."

From her place on the outskirts, Kairi is struck with the oddest feeling. She and Sora have embraced. She and Sora have kissed. She and Sora have even done certain things past kissing. But nothing they have done has ever felt as intimate as what she is witnessing now. It's so terribly private, so terribly vulnerable… she has to leave.

And just as she tears her eyes away, she catches a solitary shining tear trickle down Sora's cheek. And that, more than anything, breaks her heart.

She somehow makes her way back outside, and ends up at the water's edge. Staring into the depths, her reflection wavers pale and blonde as Naminé tries her best to smile her reassurance. It doesn't help, of course. The pieces of her shattered heart are finer than the grains of sand on the beach. But - she clenches her jaw in determination - she's strong. She has to be. She'll get through this.

She isn't blind, and she isn't naïve. She knows that Sora and Riku are, and have always been, a single unit. Always side by side, somehow inextricably linked. They've done everything imaginable together, and then a hundred things Kairi wouldn't have thought of in her wildest dreams. Or nightmares. They've partnered each other, pushed each other, defined each other.

She just hadn't realised that they completed each other.

Once she's seen the truth, she doesn't know how she could have missed it. Days pass and it's right there, shimmering elusively over everything they do. Everything that could pass as friendly to the untrained eye is oh so much deeper. The smiles - gentle, trusting, encouraging. The touches - sweeping, lingering, always wishing for more. The looks - yearning, needing, loving. They express so much more than words ever could. They are a world away, and she is all alone.

The three of them are best friends, and she's always understood somehow that one day one of them would be left behind. She just didn't know that the one was her, or that the day had come.

She knows, of course, what she must do. Her grandmother's lesson is still bittersweet in her memory. The boys would never break her heart. All her life they've wrapped her in cotton wool. She is their princess, fragile and porcelain, and as knights they've only ever lived to protect her - even when she hadn't wanted it. Even when she would have preferred to have been sparring or swimming or racing. They've done everything for her, and now it's her turn.

They are on their island, draped lazily over that palm tree. Their palm tree. Like so much else, it belongs to them, and they just allow her to share. Looking back, it seems like maybe that was the way their whole childhood has been.

They both stand as she approaches. Sora moves forward; ready to give her a kiss on the cheek. And this time she sees the dip of his head. The resignation. It shouldn't be like this. This isn't what she wanted. Her vision grows hazy at the edges, and she knows that soon, she is going to cry. But not yet. She can't yet.

She blocks his kiss - if his lips touch her she doesn't know how she'll cope - and he looks up, blue eyes snapping in surprise. She pauses for just a second to take him in. One last memory of him as her butterfly child with the ocean eyes. There's tan and sapphire and the chocolate-coloured bunny-feet-soft hair that smells like strawberries. And his purity and innocence even through everything and the gentle way he smiles and God, he's just Sora.

He's the love of her life, but he doesn't belong to her. She just wants him to be happy. And that means setting him free.

"Sora," her voice cracks and wobbles, unsteady like the rain, but she takes a deep breath and forces herself to continue. "I can't do this anymore."

The looks slashed on the boys' faces are mirror images of confusion.

"What do you mean?" Sora asks, and he is worried. About her. That's too much.

She doesn't dare open her mouth because there's a sob in her throat just begging for an exit. Her blue-violet eyes plead for understanding. And then, mercifully, recognition dawns over Riku's features. He winds a supporting arm around Sora's waist. And it doesn't hurt as much as Kairi thought it would. Maybe because it's so obvious that that's where they're meant to be. Like a jigsaw puzzle. Like a celestial tessellation.

She watches as Sora's expression flashes from shock to unease to hope to comprehension and then, finally, to gratitude. And then she sees it. He's flying away from her. She's releasing him to Riku, who's another gypsy soul. They're exactly the same through all their differences, and Sora loves him in a way that he'll never love her. This is the way it should have been.

And she's broken and she's lost. Her chest aches and she knows she's torn and bleeding somewhere she can't even define. There are so many things she wishes she could have done differently. So many things she should have said and never did. But now, here, there can only be one.

"I'm sorry."

I love you. And now you are free.