Their story starts in Seulgi’s treehouse.

Son Seungwan lives on the same street as her best friend. Kang Seulgi is a few days older than she is, slightly taller than she is, but with hands that fit hers perfectly. Mr Kang builds a treehouse for them. He assembles it board by board as she and Seulgi wait with wide eyes and bated breath. She spends an eternity in that treehouse, having tea parties with Seulgi’s teddy bears and trying to braid Seulgi’s hair.

Seungwan is five when people begin to Remember. Memories of past lives, memories of who they used to be, would slowly trickle into the minds of people after they turn eighteen. For those that are older it hits like a freight train, ramming years, sometimes decades of memories into their brains in the middle of the night.

Mother and father wake up screaming. Things are different for a few days. Then they talk and things are the same again. They tell her they were together in a previous life, married in a previous life, parents in a previous life. Seungwan sees a new light in their eyes. The same love but now with an extra sparkle.

The TV tells her that Romeo and Juliet have met again. She’s not too sure who they are but mother and father laugh and laugh and laugh.

Seulgi and her brother come knocking and ask if they can stay the night. Mr and Mrs Kang have been yelling since they Remembered and Seungwan can hear them through the walls. They put Taemin in the guest room and Seulgi with Seungwan. Seulgi, usually her big spoon and her protector, curls into her, face pressed into her stomach. Seungwan waits for tears to wet the front of her sleepshirt, but Seulgi doesn’t cry.

She wakes when the moonlight streams through the window and pools around her face. The bed is cold and Seulgi is missing. Seungwan wipes her sleep-smothered eyes and grabs a spare blanket from the closet. She heads outside, making sure to creep silently through the house.

She stares up the treehouse and sees Seulgi’s slumped form bathed in moonlight. Little Seungwan ties the sweater around her waist and begins to climb. The rungs of the ladder are cold and her sleepshirt is thin and Seungwan shakes in the quiet night. The treehouse looks like it’s a world away, but that’s where Seulgi is and that’s where Seungwan will go.

It feels like a lifetime and forever, but Seungwan makes it to the top. Seulgi lunges for her the moment she’s safely inside, winding her arms around Seungwan’s neck and burying her face into Seungwan’s chest.

Seungwan wraps the blanket around both of them and Seulgi's hair as she begins to sob. She holds Seulgi until the sobs turn to sniffles, until the sniffles fade and Seulgi is snoring gently on her chest. She watches moonlight get caught on Seulgi’s lashes and tears gleam on her star-stained cheeks. Seungwan holds Seulgi tight and whispers promises into her hair.

Mr Kang finds them in the morning, a tangle of limbs and broken hearts.

An expensive looking car pulls up and Mrs Kang leaves. Seulgi watches her go, gripping her brother's shirt with one had and holding onto Seungwan with another. Seulgi’s fingers dig into her arm, but Seungwan doesn’t take it back.

Every morning, Seungwan opens her door to see Seulgi with her hand extended for Seungwan to take. Mr Kang drops them off at school and Mrs Son picks them up.

Seulgi only lets go of Seungwan’s hand to open the car door.

Seungwan’s teen years are filled with gangly limbs and acne breakouts and thoughts of her best friend. She thinks about Seulgi’s eyes and Seulgi’s legs and the way Seulgi’s tongue darts out when she’s being cheeky.

Seulgi shoots up like a well-watered plant and Seungwan is envious. Then she discovers that it means she fits perfectly in the curve of Seulgi’s neck and that Seulgi can throw an arm around her shoulders and rest her chin on Seungwan’s head.

They’re in the same year and the same class and Seulgi sticks to her like a bur. They’re only apart when Seulgi takes a dance elective and Seungwan takes music. Seulgi collects friends like postage stamps, but she never leaves Seungwan behind.

They are Seulgi and Seungwan as they were before.

They’re together on the couch, Seungwan in Seulgi’s lap, being used as a teddy bear and human shield against the gore that’s on the screen.

‘Why’d you pick a horror movie, if you’re gonna hide behind me the whole time?’ Seungwan rubs a thumb over Seulgi’s clasped hands over her waist, wanting her to know that she’s only teasing.

‘This was the only way to get you on my lap! I missed my Wannie!’ Seulgi nuzzles against the back of her neck and tightens her hold.

Seungwan feels her cheeks start to burn. ‘Don’t you hate skinship?’

‘Not when it’s with you!’

Seulgi rests her forehead between her shoulder blades and Seungwan feels her heart swell three sizes.

‘God, you’re so greasy.’

‘Only for you.’

She secretly adores greasy Seulgi.

Seungwan thinks that her best friend is perfect, inside and out, body and soul and everyone seems to think so too. Everybody seems to want a slice of her best friend, a piece of her Seulgi.

They share a locker. Seulgi has the one on top and she has the one on the bottom. Seungwan grits her teeth whenever she spots Sunmi-sunbae leaning against it. She’s always waiting for Seulgi, leaning on Seulgi, fluttering her eyelashes and laughing obnoxiously with Seulgi.

‘Just call me unnie!’ Sunmi says, blinking rapidly like she has some sort of allergic reaction to pollen.

‘Okay, Sunmi-unnie.’ Seulgi beams like the super oblivious best friend she is and Seungwan resists the urge to drop her incredibly brick-like advanced physics text book on Sunmi-unnie’s foot.

Seungwan is pouty and silent as they walk home together. She walks faster than they usually do and when Seulgi tries to link their pinkies together, like they usually do she petulantly moves her hand away.

It’s the only time she does this.

She misses Seulgi too much to do it again.

Seulgi confuses Seungwan.

She makes Seungwan feel butterflies and centipedes and Xenomorphs in her stomach and she wouldn’t be surprised if her feelings rip themselves out of her chest one day, with the way her heart aches for Seulgi.

Seungwan doesn’t know what she’s doing, doesn’t know what she’s feeling. And she can’t do what she always does because knocking on Seulgi’s door to tell her “you make my heart feel funny” isn’t going to make her inner turmoil any better.

So Seungwan bikes all the way to Cousin Sowon’s house.

Cousin Sowon with a wife and a baby and two puppies opens the door to Seungwan’s despondent puppy eyes, sighs and tells her to come inside.

‘You, Son Seungwan, like Kang Seulgi.’

‘Of course I like Seulgi! She’s my best friend!’

‘More than a friend, Seungwan.’

‘Oh.’

‘Here, have a scone. And I’ll tell you how I met my wife. ’

Seungwan watches the way sunlight from the window hits Seulgi just right. Seulgi has given up on working on her poem and is making funny faces to balance her pencil on her upper lip. She should look ridiculous, and yet all Seungwan can think about is the lush curve of her lower lip and the way the sun highlights her jawline and casts shadows on the lithe line of her neck.

She looks down at her empty page. She only has a single line doodled down. Seulgi, summer’s day, hot.

Seungwan feels her cheek burn as if the summer sun has kissed it. She crosses it out hurriedly, until she feels the tip of her pen cut through the paper and scrape against wood.

She thinks of summer and funny faces and Seulgi and puts pen to paper.

Mr Shakespeare, literally William Shakespeare, the wordsmith reincarnated, and somehow their high school English teacher, gives her an A for her poem.

Seungwan wants to tell Seulgi that Seungwan wants to kiss her.

Seulgi is perfect and kind and sun-kissed and there’s a glow to her that makes it hard for Seungwant to stare at her for long periods of time. But when she looks away from Seulgi there’s flaming circles in her eyes and a sense of loss in her chest.

Seulgi is her best friend and her soulmate and her other half. What they have, it’s good. They laugh, they cry, they hold each other tight.

And Seungwan doesn’t want to mess all of that up. If she says anything she won’t be able to take it back. It could irreversibly change their dynamic and Seungwan won’t risk it, not for the slim chance that Seulgi might love her back the way Seungwan wants her to.

Because Seulgi loves her now. And Seungwan doesn’t want that to change.

Seulgi coos as “Moonbyul-unnie” flexes her arms in her ridiculously punk rock tank top and Seungwan tries her best to not roll her eyes. Even though she really, really wants to. There’s barely any definition. Definitely not worth Byul whipping off her hoodie and flexing for Seulgi right in front of their shared locker. Why does everybody always find Seulgi here, can’t they do this when it’s just Seulgi and not Seungwan and Seulgi.

‘I’ve been hitting the gym and you can really see a difference!’

‘You’re looking so toned, unnie!’

Seungwan can’t see much of a difference. Not one worth mentioning anyway.

Seungwan watches as Seulgi drags her long, elegant fingers over the barely defined curve of Byul’s bicep and surreptitiously slides her own under her sleeve to squeeze at her own. Then she adds a few notes to her daily planner.

Join gym? Adjust diet? Get swole!

If Seulgi likes toned arms. Seungwan will show her what they’re meant to look like.

Every morning, well before the sun is up, and way before Seulgi is at her door, Seungwan wakes and runs. It’s so early the stupidly high-pitched birds nesting outside her window aren’t even awake yet.

Whenever she thinks about giving up and staying in bed, she thinks about Byul’s smugness and swagger and the fire that flares up inside burns all the thoughts to ash.

She gets sweaty, she gets tired, and every time she gets out of breath, she thinks about Seulgi’s eyes and Seulgi’s coos and Seulgi’s stupidly pretty fingers tracing her arms.

And then she runs faster and harder. Angry that she can’t outrun her thoughts of Seulgi.

It keeps happening. Other girls keep...launching themselves at her best friend and Seungwan is getting sick of it.

It doesn’t bother Seungwan that Seulgi is popular with the ladies. Well, it does a little.

But she sees girl after girl, mustering up their courage to talk to Seulgi, to ask her out on dates, and all she can think is that they are far braver than she could ever be.

They’re open with their romantic intentions while she hides hers away. Like she’s some sort of sad love mushroom and they’re rose bouquets.

‘Seulgi-unnie! Could you walk me to class?’

Yoo “Call me YooA '' Yeonjoo is an underclassmen that’s in Seungwan’s maths class because her brain is as insanely smart as she is adorable.

Seungwan watches incredulously as YooA backhugs Seulgi without a care in the world. As if Seulgi didn’t have an armful of Seungwan’s textbooks. As if Seulgi wasn’t linking pinkies with Seungwan. As if she’s allowed to hug Seungwan’s best friend, Seungwan’s Seulgi.

And then Seulgi turns to her, soft Seulgi, gentle Seulgi, Seulgi who is literally the light of her life, Seulgi who says ‘Wannie, I’m gonna walk Yeonjoo to class! I’ll be right back!’ She returns Seungwan’s textbooks and then she’s off, being dragged by YooA to wherever her class is.

Seungwan stares incredulously, slacked jawed as Seulgi and YooA flounce down the hallway. She feels a little betrayed. She marches off to class, anger simmering in her veins and thunder flickering across her face. Other students part like a she’s a hot knife and they’re off-brand margarine.

Whatever. She’s perfectly capable of walking to class by herself. Unlike YooA.

Seungwan dominates the maths class rankings for the rest of the year, ousting YooA as Queen of the Mathletes and Mr Kim actually tears up a little when he meets her parents.

They’re seventeen when Seulgi gets a girlfriend. Seungwan isn’t surprised but it hurts anyway.

Bae Joohyun, prettiest girl in school, Galatea made flesh, Seulgi’s favourite dance partner, laughs as Seulgi tries and fails to do the splits. Her laugh sounds like angels singing or birds chirping or flowers blooming and Seungwan plots the points of her parabola with so much force that the lead snaps.

She’s got her stupidly perfect hands wrapped around Seulgi’s ankles as she tries to teach Seulgi the stretches necessary to perform the split. Bae Joohyun leans in so close that her hair brushes Seulgi’s shoulders and her cheeks brush Seulgi’s neck they’re so close they’re nearly kissing.

And then Seulgi turns and Joohyun leans in and their lips meet in a perfect hollywood kiss.

Seungwan snaps her pencil in half.

They eat lunch with Joohyun and her friends. Sooyoung is in Seungwan’s physics class and Seungwan knows Yeri, because everyone knows Yeri.

Joohyun is lovely, so very kind and sweet that Seungwan can’t find it anywhere in her heart to be angry at her for taking her best friend away.

Can’t hate her for being brave where Seungwan was a coward.

But there is anger in her being. It sits between her ribs, to the left and a little higher than where her heart is. It eats away at her, slowly and steadily, it consumes her like one of those flesh-eating viruses Mrs Jung had taught them about last week.

Seulgi still walks her to school in the mornings, she just doesn’t walk Seungwan home anymore.

Seungwan swings her hand in wide circles and feels a phantom touch where Seulgi’s should be.

It’s movie night and when Seulgi moves to pull Seungwan onto her lap, Seungwan hastily side steps and sits next to her instead.

‘You’ve got a girlfriend now.’

‘But that doesn’t mean we need to stop cuddling!’ Seulgi says this with a beaming smile, eyes curved into gleaming crescents.

And Seungwan wants to indulge her. But she needs to do this for herself. Seulgi doesn’t like her like that and she needs to stop making it difficult for herself.

She hands Seulgi a throw pillow. ‘You can hide behind this.’ Seungwan turns to the screen and pretends that she doesn’t see Seulgi’s smile slide off her face.

Her body seeks Seulgi’s touch and Seungwan has to consciously keep herself from leaning into her best friend’s warmth. She sees Seulgi’s hands twitch, white-knuckled from way they’re digging into the cushion, and tries not to feel too guilty.

Joohyun, Sooyoung and Yeri grow to become their good friends. And Seungwan lets go of the last remnant of silent animosity that she feels toward Joohyun. It’s not her fault that she fell for Seulgi, this Seungwan can understand. They’re watching a movie on Seulgi’s battered couch, Seulgi on one side, with Joohyun next to her, Sooyoung on the other side and Yeri sprawled out on the floor attempting to tickle Sooyoung’s feet.

Seungwan returns from the kitchen with a bowl of freshly buttered popcorn. She hands it to Yeri who’s making grabby hands and shooting her puppy dog eyes with a pat to the head. Then she stares at the full couch and blinks.

There’s never been this many people, it’s usually just the two of them. But things are different now, so she shrugs and sits on the arm of the couch.

‘Seungwan-unnie! Come sit with me!’ Sooyoung smiles at her so hard her cheeks squish up and holds her arms out. She looks so hopeful, so expectant that Seungwan can’t deny her this. She hops onto Sooyoung’s lap, lets Sooyoung wrap her hands around her hips and keep them there.

Seungwan ignores the betrayed look on Seulgi’s face and how she keeps shooting looks at them throughout the movie.

Sooyoung hooks her chin over her shoulder and she can feel Seulgi’s gaze grow piercing.

Joohyun goes off to college and they see her less and less. She leaves her number and her email and Seungwan makes sure to message her twice a week.

Joohyun and Seulgi break up and nobody is surprised. But they manage to stay friends and they make sure to watch movies at Seulgi’s house when Joohyun comes back.

Seating arrangements are slightly different now. Yeri stays on the floor, but Joohyun and Seulgi swap spots. When Seungwan comes back with popcorn and Sooyoung holds her arms out, Seulgi carefully plucks the popcorn from Seungwan’s hands and shoves the bowl into Sooyoung’s arms.

Jooyhun and Yeri’s eyes don’t leave the screen, extending their arms to retrieve popcorn and chewing mechanically, too invested in the movie to care.

Sooyoung always blinks, blindsided, as Seulgi drags Seungwan onto her lap.

Seulgi turns eighteen and Seungwan finds her in her bed when she comes home from band practice. Seulgi lunges for her the moment she steps inside, winding her arms around Seungwan’s neck and burying her face into Seungwan’s chest.

Seulgi is grumpy for a few days, the headaches that come from Remembering are supposedly very painful, clinging to Seungwan’s back everywhere and refusing to let go.

The teachers shrug and let her get away with everything because they understand that a lifetime of memories will take some adjustment. Mr Kim slips Mr Shakespeare a $50 note and he has this -eating grin all through English class. He pairs them up for the English project because they’re “so attached already”.

Seungwan spends a week with Seulgi latched onto her like an unusual, but very cute parasite. Seulgi’s hands are always wrapped around her and it should feel suffocating, but it doesn’t. She’s missed Seulgi’s casual touches.

Seulgi glares when Kyungsoo-sunbae offers to carry her books to class, detaching herself and picking up Seungwan’s books herself. She bats Sooyoung’s hands away when she tries to pull Seungwan into a bear hug at their lockers. She growls when Taeyeon-unnie asks Seungwan on a date.

Seungwan reaches her arm to at Seulgi’s hair until she calms down. Seulgi makes a soft, satisfied noise and noses into the back of her neck.

Taeyeon-unnie steps backwards with wide eyes and Seungwan quickly shoots her an apologetic look.

Seungwan turns eighteen and there’s nothing. No headaches, no memories, just Seulgi pressed against her back and long fingers sneaking themselves under her sleep shirt to splay out against her stomach. She carefully untangles Seulgi’s limbs from hers and sneaks outside.

Nostalgia brushes over her like cobwebs when she enters the treehouse.

She sits and waits.

Seungwan watches at Seulgi climbs up to where she is. Her hands are almost too big for the rungs now, and the ladder sways with every step.

She extends a hand when Seulgi is near the top and drags her all the way in. She pulls a little too hard and Seulgi ends up sprawled on top of her. Moonlight filters through the window and leaves and paint Seulgi in silvers and blacks.

They’re a tangle of hearts on the floor of Seugi’s treehouse and Seungwan waits with her heartbeat in her ears as Seulgi leans closer and closer and closer. Soft lips press tentatively against hers and she can feel Seulgi grow tense and pull back.

Seungwan is sick of being scared. And sick of being selfish. Seulgi has taken all these steps for the both of them and she just needs to take this one.

Seungwan winds her arms around her best friend’s neck and pulls her lips back onto hers.