Dear Past Seulgi, 

You are an idiot. Do not, I repeat, do not ever let your guard down.

Sincerely, Future Seulgi

How did it come to this? Seulgi sighs, as she stands in the middle of the huge Park backyard, searching for the children. It was supposed to be a simple, easy and innocent game of hide and seek. Joohyun and Seungwan were about to prepare dinner, and suddenly Joy wanted to play and of course whatever Joy wanted to do, so did Yerim.

Seungwan shakes her head, and before Seulgi can start counting, she whispers, “They usually hide together in the backyard.” 

Thank the heavens for Son Seungwan. 

But Seulgi swears, do these kids have invisibility on top of the possible teleportation skills?! Cause she can’t find them at all. She already went around the backyard once, checked the entire living room, even checked the kids’ room and Joohyun’s room and nothing! Panic slowly starts to creep up her body. What if they hid in their parents’ room?! She can’t check there! Or worse… What if she actually lost them?! Joohyun would never forgive her! Though honestly, she’s sure Joy could survive anything on her own. Yerim on the other hand, well she’s 3! Of course she can’t! But then again… if they got lost together… 

Seulgi shakes her head. No. They’ve got to be here somewhere, right??? 

Then, just as she’s about to ask Seungwan for help (no way is she going to let Joohyun know), she hears it - the distinct sound of bubbly laughter coming from the playhouse at the side of the backyard. Her brows furrow together, she swears she’s checked there already but whatever, she’ll blame it on her bad eyesight. 

She tiptoes to the playhouse, making sure they won’t have a chance to escape, and she peeks inside through the small window, spotting a huge blanket covering something very Joy-shaped.  

Seulgi smirks, and she begins to crawl, quietly opening the door. 

Wow. They sure know how to keep still.

“I GOT YOU!” Seulgi shouts, yanking the blanket off only to reveal a Joy-sized stuffed bear with what looks like Joohyun’s phone on its lap. On it, a video of Yerim and Joy laughing is playing on loop. Then, before Seulgi can even fully process it, the door slams shut and she hears the very very very distinct cackle of a six-year-old. 

She crawls to the window to see Joy and Yerim laughing their little butts off.

“JOY!” Seulgi hisses. “Get me out of here!”

Joy just smiles, “Nope.” 

“Yerim, help Seu-unnie?” 

Yerim looks at Joy who shakes her head, and Yerim giggles, “Nuh uh.” 

Seulgi pulls at the knob. 

“Eomma put a lock so we won’t play inside at night.” Joy says, waving a key in front of Seulgi’s face. 

Seulgi groans, this kid is way too smart. She pats her pockets for her phone hoping to call Seungwan without alerting their sister. Then she remembers how Joy saddled up to her before they started playing hide and seek, asking if she had any games on her phone. 

This demon.
 

“Jooooy,” Seulgi calls out, “Your unnie won’t like it if she sees me in here. What is she gonna say? She knows you’re a good kid.” 

For a second, Joy stops smiling, then she crosses her arms. Seulgi gulps and she hopes Joy can’t see the fear in her eyes. 

“Come on, let me out! I won’t tell your unnie, promise.” Seulgi tries again. Honestly, all she wants is to get out before Joohyun finds her because how pathetic would it be? If she told Joohyun the truth, then Joohyun would think she’s dumb enough that a six-year-old can trick her. Or even if she didn’t tell Joohyun the truth, what adult gets stuck in a playhouse?!

As she contemplates what to do, she hears Joohyun call out from inside, “Joy, Yerim! Time to wash up before dinner!” 

And instead of looking worried, Joy smirks. (It honestly gives Seulgi chills.) Then, she turns her back on Seulgi, starts running towards the house while shouting, “Unnie, unnie! Seulgi unnie got locked inside the playhouse!” 

That’s when it dawns on Seulgi. Joy knows. She wants Joohyun to see Seulgi in here. She knows Seulgi looks ridiculous and she knows anyone would think so too.

“Joohyun, hi!” Seulgi squeaks, as Joohyun appears in the backyard, Joy clutching her arm dramatically actually looking worried for Seulgi. (This kid is gonna be a great actress one day, Seulgi thinks.)

Joohyun laughs at the sight of Seulgi barely visible from inside the playhouse, “Yah, what happened here, Seul?” 

“Well, we were playing… and… yeah...” Seulgi trails off, unable to look Joohyun in the eye. 

Joohyun kneels down, unlocks the door and sticks her head inside, “It is kind of cozy inside though.” 

“Y-yeah. I guess so.” 

“Oh, that’s where my phone was.” Joohyun comments, and crawls into the tiny space, reaching for her phone that’s still on the Joy-sized-bear’s lap. Seulgi wants to faint, because Joohyun is so close, and she’s so much prettier up close, and the playhouse is so small and she can practically feel the warmth of Joohyun’s body and-

“Unnie, hurry, please! I’m hungry!” Joy interrupts from outside. 

Joy I swear-

“Hungy!” Yerim shouts. 

“Yeah, yeah!” Joohyun shouts back, then she turns to Seulgi and says, “Come on, let’s not keep them waiting.”

Joohyun slips out of the playhouse with ease, and all Seulgi can do is nod as she follows and pray that her face isn’t red enough for Joy to make fun of. 

Despite Joy being Joy, clinging to Joohyun as often as she can, or telling Yerim to do it for her, Seulgi can confidently say that in one week alone, she’s already learned more than her entire thirteen years as a student.

Joohyun and Seungwan are so smart that by proximity alone, Seulgi feels that she is already getting smarter. But it’s not just that. Seungwan may talk a mile a minute but she also has the amazing ability to make all those complicated trigonometry formulas make sense in Seulgi’s head. (She also has really funny expressions and moves her hands around a lot when she explains, so it’s a very entertaining lesson. It’s also made a hundred times funnier when Joy imitates Seungwan’s gestures and the highschooler has to tickle the little girl to get her to stop.)

Then, when Seulgi rests her head on the table, groaning about how hard physics is and how she’ll never need physics in the real world anyway, Joohyun gently pats her head and says, “Want me to prove you wrong?” and the look Joohyun gives her is so competitive and so intimidating that Seulgi can only nod in reply. “Do you still want to be a professional dancer when you grow up?” 

“Uh- yeah- how’d you-” 

“Look at what you’ve done.” Seungwan says, shaking her head at Joohyun who’s frantically searching for something on her laptop. “You’ve unleashed her competitive side.” 

“You basically already know all about physics, it’s just in your muscles.” Joohyun starts, eyeing Seulgi’s body from head to toe and Seulgi can’t help but blush at how she’s being watched. Joohyun then spends the next thirty minutes explaining how gravity, friction, and torque are just a few of the physics concepts that can affect a dancer’s spin, a grand jete or even a lift with a partner. All Seulgi does is watch in awe because yes, Joohyun is right, but Joohyun is so passionate and her eyes are so bright that Seulgi can’t help but stare in wonder. 

That is, until Joohyun is apparently finished talking and Seungwan interrupts Seulgi’s thoughts by flinging an eraser at her head. 

“OW!” 

“Wan! Joy might copy you!” Joohyun scolds and her best friend raises her arms in defense. “She wasn’t paying attention!” 

“Yes, I was! And okay, you’ve proved me wrong. I promise I’ll be a better student.” Seulgi says and the sheer look of pride on Joohyun’s face makes Seulgi want to cup her cheeks and give her a little kiss on her forehead. 

But aside from school, Seulgi learns a lot of other things. 

She learns that the Park parents are both doctors, Mr. Park is a surgeon, while Mrs. Park is a pediatric cardiologist. It explains why Joohyun takes care of the two monsters, with both parents busy working in the hospital with really crazy hours. It also explains why Seungwan is also with them so often, her parents constantly abroad or working late as executives in the same company, (“They met on their first day on the job, can you imagine?” Seungwan explains with a roll of her eyes) and at least when someone makes dinner, the other can watch the kids.

“We’ve got this whole taking-care-of-the-kids-thing down to a science.” Seungwan says over the dinner that Seulgi bought for everyone, as thanks for teaching her. 

Joohyun nods in agreement. “Like even when we go to Dahyun’s? It’s one and a half scoops of ice cream each. That’s enough to fuel them until we get home and get them cleaned up. Then by the time dinner rolls around, they’re hungry enough to finish at least most of their food. Around 9pm, they’re conked out.” 

“How’d you figure that out?” 

“Lots and lots of trial and error. Half a cup of ice cream and they’ll be in a bad mood. One cup is usually okay but Joy will ask for more and try to sneak some anyway. If Joy still wants more, then another half cup isn’t so bad. We also can’t give unequal amounts because then Yerim will start to whine and then Joy will defend herself and it’ll just cause a massive he