It was a nice Friday afternoon at the L/N household, with you spending your afternoon playing video games online with Garth and Barry. You then see what time it is and remember you have to take care of your sister when she gets home from school

Y/n: Alright guys, that's gonna be my last round. Maddie's gonna be home soon and my parents are still at work, so I'm on babysitting duty again

Garth: Boooo

Barry: No sweat Y/n, we'll finish up tomorrow

Y/n: Alright, later guys

You log off just as you hear the front door open and Maddie yell that she's home

Maddie: Y/N! I'M HOME!

Y/n: Yeah yeah, I'm comin' 

You make your way downstairs to see Maddie standing next to another girl who has her back turned to you

Y/n: Who's your friend?

The girl turns around and reveals herself to be...Lena freaking Luthor

The same Lena Luthor who tried to kill you on your first day of school...

You just stood there shocked as Lena crosses her arms and sticks out her tongue at you

Maddie: This is Lena, she transferred to my school a few months ago

Y/n: Oh, well nice to meet you, Lena. I'm Y/n, Maddie's brother

Lena: Do you have any snacks? I'm hungry

Y/n: Yeah, we have some in the kitchen, I'll make you guys something

Maddie: Thanks, Y/n! You're gonna love it, he's an amazing cook. C'mon, let's play in my room!

Lena: Okay

Maddie and Lena head upstairs to her room while you start making grilled chicken sandwiches for them. Once you were done you bought them up to the girls along with some juice

Y/n: Here ya go

Maddie: Thanks, Y/n!

Lena: Thanks, I guess

Just then you hear your phone ring, so you fished it out of your pocket and answered it, only for Kara to yell at you through the phone

Kara: Y/n! Where are you?!

You accidentally hang up on her and sheepishly leave the room to call her back. After getting to a safe enough distance away from the girls, you call Kara again

Kara: Did you seriously hang up on me?!

Y/n: Sorry, it was an accident, what's wrong?

Kara: Lexbots at the pier again, and they mean business! I swear this Lena brat never lets up with this place!

Y/n: What? Ugh, I'm stuck babysitting Maddie right now, and besides, how can it be Lena? She's at my house right now!

Kara: Why is she at your house?!

Y/n: Playdate with Maddie. Alright, I'm on my way just hold on tight while I figure out how to get out of here

You hang up the phone and walk back upstairs to Maddie's room

Y/n: Hey, I gotta head to the store, Do you need anything?

Maddie: No, I'm fine here

Y/n: Lena, do you want anything?

Lena: The complete and total annihilation of teenagers 

Y/n: What was that?

Lena: Oh! Just some sour candy

Y/n: On it

You leave the room and head to your bedroom and change into your costume. After that, you jump out of your window and start swinging over to the pier. Meanwhile, Maddie and Lena were playing with a dollhouse you had bought her

Lena: Does your brother leave you home alone often?

Maddie: Only for emergencies really

Lena: Going to the store counts as an emergency?

Maddie: Oh he just says that when he needs to stop a bad guy

Lena: Oh, okay then

Lena takes a sip of her juice only to do a spit take at what Maddie just said

Lena: What?!

Maddie turns on the news on her tv which shows them documenting the events of what happened at the pier

News Anchorwoman: Massive mayhem on the pier today as Metropolis' own "Superhero Girls" take down rogue LexCorp construction bots with help from our very own "Malleable Martyr" Plastic Man. LexCorp insists they have no idea as to why their technology would go rogue and attack civilians, but they take solace in knowing our group of heroes was there to save the day before anyone got seriously injured or worse. We'll have more to cover on this matter at 11

Soon as the report ends, you walk into the room, back in your regular clothes and holding some sour candy you nabbed from the pier

Y/n: Hope you like these, they were all I can find

You notice Lena staring at you, then back at the TV, then back at you, then at Maddie, then back at you

Lena: No way...you're-!

At that moment the doorbell rings, so you run to go get the door, only to see Lex Luthor there

Y/n: Lex Luthor? Oh, are you here to pick up Lena?

Lex: Yeah? My mom told me she was having a "playdate" at a friend's house. Please tell me you aren't that friend...

Y/n: Oh, no I'm Y/n, her friend's older brother. C'mon in, can I get you anything?

Lex walks in and takes into your home's decor

Lex: Nice house, and no thanks, I'm okay

Y/n: Alright, well they're upstairs in my sister's room if you wanna follow me

You and Lex walk upstairs to Maddie's room 

Y/n: Lena, you're brother's here

Lex: C'mon, we gotta get home quick. Mom's making meatloaf tonight

Lena: Ugh not meatloaf. Alright, I'll admit, I actually had fun today Maddie. Can I come again soon?

Maddie: Sure! I'll make sure Y/n cooks more yummy food too whenever you're here

Y/n: I guess I'm just gonna be their personal butler going forward...

Lex: Seems like it

After saying your goodbyes to each other, Lex and Lena climb into the back of a car and head off, while you and Maddie wave at the car as it drives off. Inside the car, Lena looks out the window while Lex is on his phone

Lex: So, you had fun using my robots to try to destroy the pier again?

Lena: What's it to you, jerk?

Lex: I'm just askin'

Lena: Yeah, I did have fun...and I found out some juicy things...

Lex: What? Like your friend had a secret she told you?

Lena: You can say that, and boy it's a doozy

Lex: Alright, well leave me out of whatever third-grade drama you guys are into, and stop stealing my robots!

Lena continues looking out the window while thinking about you

Lena: Can't wait for my next visit...Plastic Man!