Annihilation – The process in which huge energy is released when a particle self-destructs upon meeting its anti-particle.

Part I

Tuesday – 20:35

It was late and Santana was biting her lip, trying to keep herself from shaking. She was worried. Quinn was supposed to be home from work an hour ago and now the food was going cold.

Santana sighed and lifted the plate of spaghetti carbonara from the table and headed for the fridge. She placed it inside, pressing her forehead against the cool refrigerator door when she closed it again, in the darkness.

Her doorbell rang.

Wondering who it could be, Santana made her way to the front and opened the front door. And there, in a purple raincoat, stood Quinn.

"I'm so sorry for being late," Quinn said with a shy smile.

Santana sighed in relief, matching her smile. "Why did you ring the doorbell? You could've just come in."

"I know," Quinn was still smiling cutely, her cheeks a faint, rosy-pink shade. "I just didn't want to disturb you."

"Oh, silly Quinn," Santana shook her head good-naturedly and leaned forward to peck her girlfriend on the lips. "Come inside, I was so worried! I'll heat your food up…"

Quinn nodded gratefully and walked inside, trailing a cold, lean finger on the doorframe before she closed the door behind her.

Tuesday – 21:20

I take the earbuds out of my ear as I thank the taxi driver, paying him. It had been a super long day at work, and I am so tired! All the people in my law firm drive me crazy, I swear, their standards are so high and they care about the smallest of things.

Talk about OCD. Sigh.

And now I'm two hours late… hopefully Santana won't be mad at me for making her worry. I also hope she hasn't waited for me to eat dinner… I tried to call her but my phone was dead and I didn't bring my charger with me.

But all of that doesn't matter. Because I'm home, and I can see my girlfriend again after such a long day at work! This is my favourite part of the day for sure, because… well, I love her. More than anything.

I walk briskly through the light rain as I ascend the stairs to our apartment. I consider ringing the doorbell, but I don't want to disturb Santana so I opted to let myself in. The keys jangle between my fingers as I fumble with the door lock, but eventually I manage to unlock the door and make my way inside.

And the first thing I realise, is that it is incredibly dark. No light is on.

I fumble blindly for the light switch somewhere on my right before I finally find it, and the light flickers for a few seconds before staying on. I take off my purple raincoat and my shoes, placing them neatly on the rack beside me.

The light flutters a few times before it switches off and stays that way.

"Damn it," I whisper. I need to tell Santana to get some lightbulbs tomorrow.

My eyes have adjusted somewhat to the dim lighting so I can see a bit. I walk into the living room and that's when I hear something that shakes me to the core.

Moaning.

What the hell? I've got to be hearing things, right?

I freeze and don't dare to move a muscle, and silence is all I hear. But then, a few seconds later, the bed cracked and another loud moan made its way to my ears.

Then another moan, from another person. A voice I can recognise from anywhere. Santana's.

"O-Oh," an uncanny voice was moaning as the bed creaked again. "S-Santana, I'm… so close… there…"

"W-What?" I whisper to myself, completely frozen and having no idea what to do. Santana's having sex with another person right now… what?

Santana's cheating on me.

What the fuck do I do? Should I leave them to it? Or should I go in and stop them?

I can't help uncontrollable tears from escaping my eyes. Santana's cheating on me.

But… why? Did I do something wrong? I swear a few days ago we were fine… or was she leading me on the whole time?

Stifling a sob, I make my choice. I can't let Santana go. I need to stop them.

The unknown woman's climaxing scream eclipses my loud footsteps before I open the door to our bedroom and stumble in.

It's still dark, but I can see exactly what's going on. Santana's butt-naked, fucking a woman underneath whose hair was sprawled around the bed, but I can't see her face.

My vision blurs as my eyes fill with tears again, my hand flying to my mouth to block any sound from escaping.

I don't get it. I don't get anything.

"Oh," Santana sighed softly, rolling off the woman and lying down next to her, still above the covers. "Q-Quinn… that was amazing."

Wait, what? Quinn?

The woman sighs happily as she leans towards Santana and places her head on the brunette's shoulder, and that is when I could see her face for the first time.

And my eyes widen in horror.

She looks exactly the same as me.

What the fuck is going on?

The woman raises her head too and sees me. Santana is still oblivious.

I hold her hazel gaze for god knows how long, before she scrambles backwards and screams in fright.

"Quinn?" Santana is alert immediately, sitting up against the bed and that's when she sees me too.

"S-San… she's here," the other version of me was whispering as Santana looked at me quizzically.

"What? I-I thought you were joking!" Santana said, hugging the other version of me close to her chest protectively as she stares me down with so much animosity I recoil.

Santana has never looked at me this way before.

"What the fuck are you?" her voice is hard and unrelenting.

I don't understand anything. Santana is asking who I am? What I am? I'm her girlfriend of six years! But then who the hell is the woman in Santana's arms? And why does she look so much like me?

"I-I…" I stutter, but that's all I manage to get out before the blonde woman in Santana's arms screams out.

"Get out!" she cries, and it sounds exactly like me too. "Stay away from us!"

"W-Wait!" I shout, and I'm unnerved because from an outsider it must seem like a person is screaming to themselves. "I don't understand, what's going on?"

Other Quinn wipes her eyes as she takes a deep breath. "I'll talk to her, San," she whispers into Santana's ear, making sure I can hear her. "This is something I started, I have to end it."

"B-But," Santana started. "She's evil, you said," she said, fear tracing her tone for the first time as she eyes me warily. "She might hurt you."

"She won't," other Quinn reassures, rubbing Santana's shoulder affectionately. "She needs me to exist. I'll be back, okay?"

Santana acquiesces with a reluctant nod as other Quinn jumps out of bed and throws my robe over her body.

"Come with me," she hisses and leaves the room, and I can't do much other than follow her, dumbfounded.

We are in the study, and as soon as I'm inside my other self closes the door, puts a chair behind it and locks the door.

And then her expression changes.

"Well, well," she said. "Never did I think that looking at the great almighty Quinn Fabray would be like staring into a mirror," she smirked.

My jaws drop at the mirth placed behind those words.

"What the fuck are you?" I snarl, feeling irritation flare. "Why do you look just like me? Why do you talk like me too? I don't understand."

"I should've expected as much," other Quinn sighs, tracing the mahogany armrest on the chair she's sitting in. "The thing is… I can't explain what I am exactly because I am also Quinn Fabray, despite how much I don't want to be you."

"What?" is all I can say, because nothing she's saying is assuaging my confusion.

"All of my life, I have been inside you, forced to stare out of a window that was your eyes, watching myself do things I have no control of, things I don't want to do. I had no power. And now here I am."

"I still don't understand."

"Of course you don't," other Quinn rolls her eyes. "Well… how do I put it? Do you remember all these serial killer thoughts you got every Friday 13th?"

"Yes…" I say slowly. It's not wrong that every time the 13th day of the month lands on a Friday I have received incredibly disturbing temptations of killing people. Especially if it lands on a February too, then I get temptations of killing Santana. Every time I have managed to push away those thoughts, but they are getting stronger.

"That's me," other Quinn smiles.

"W-What?" I stutter. "I don't get – how come? You're a person?"

"Quinn, considering your grades, you really are not that smart," other Quinn rolls her eyes. "I'm your anti-matter, that's probably the best way of putting it."

"Anti-matter?" I frown.

"You forget all the physics you learnt in high school?" Anti-Quinn smiles. "Everything on earth has an antiparticle. A proton has an antiproton. An electron has an anti-electron, or a positron. Well me? I'm your antiparticle. A thing that has the same… rest mass, i.e. I look exactly the same as you, but exhibit opposite properties. And it's because of that, I have grown up resenting you. Because I like exactly nothing that you like."

"I-I still don't get it… so you're my clone?"

"Another way of putting it, I guess," Anti-Quinn smirks. "But that makes it sounds like you're the original and I'm the replica. But in reality… I have exactly as much right being here as you."

"I-I've never seen you before," I stutter. "Why do you only appear now? What are you doing here? And why have I never seen Santana's… antimatter?"

"Woah, Barbie, so many questions!" Anti-Quinn frowns mockingly and holds out a hand. "Well," she drawls. "Only the strongest break free. I've been trying for twenty-four years, and I'm finally out. Which brings me to my next point. What am I doing here? Well, you know how I'm the polar opposite, right? You're here to build your life. Me? I'm here to ruin it."

"But… why?" I whisper. "Why would you do this?"

"Were you not listening to me? All my life I was forced to stare out of your eyes and listen to you fangirl over stupid pop singers, watch you make friends I hate, listen to you sweet-talk your way with everybody. The worst thing? When you met Santana and started to crush on her. And when I didn't think it could get any worse, you started to date her. God, how I hate that Latina dyke," Anti-Quinn's expression morphs into one of extreme distaste. "Because you love to kiss her, I am forced to kiss her. You know, considering everything, all the praise about Santana as if she was a goddess, she is really fucking shit in bed."

My mouth drops in horror. "How can you say that about her?" I whisper, offended. "She's the most amazing person you'll ever know! I love her!"

"And since I'm the opposite of you… you can assume that I…?"

"Hate her?" I finish glumly.

"Booyah," Anti-Quinn says monotonously. "Whatever crap you see in her, I don't see. I'm fucking straight for god's sake and I was forced to be in a relationship with a girl I hated for six years. I've had enough. I'm finally free. And you know what? I'm killing her."

"You –" The way Anti-Quinn said that with so much conviction, there really is no way for her to be joking.

"What?" Anti-Quinn pouts innocently, but it has derision written all over it.

Oh god, she's serious.

"You won't kill her," I say with as much confidence as I can. "You would've done that long ago, before I got home if you wanted to. You wouldn't have… had sex with her either."

Anti-Quinn giggles and it's a sound I've never heard come out of my throat before. It's so… malignant and hostile.

"Oh, I didn't fuck her," Anti-Quinn shakes her head. "She fucked me. I don't want to touch her, no, never. Fucking gross dyke. And oh yes do I want to kill her. I hate her so much, you have no idea how much I want to carve her open. But I won't do it now – what would be the fun in that?"

My protectiveness for my girlfriend suddenly surges and that translated to anger – rage is all I feel now and it's not nice.

"Leave us alone, you sick bitch," I snarl. "I don't care if you're here, just stay the fuck out of our lives, okay? Find another antibody if you want, and stay far, far away from us, you got it?"

Anti-Quinn looks at me for a second and blinks before bursting into laughter. "I don't think you're in a position to threaten me," she snickers. "Firstly, Barbie, an antibody is a protein that's a part of your immune system, which is not what I am. I've never realised how fucking dumb you are until I got to talk to you, god knows how you managed to get into Yale, let alone work in a high-prestige law firm."

"I don't fucking care if you're smarter than me," I growl. "Just get the fuck away from us and leave us alone. You said you hated me and Santana… why stick with us?"

"Because I want to kill Santana?" Anti-Quinn quirks an eyebrow easily. "God, are you deaf too?"

"Yeah? Well, I will not let you kill her," I shake my head determinedly.

Anti-Quinn laughs. "What can you do about it?" she sneers, and never did I think my voice could pack so much… malignance.

It's just everything… her smug little smile, her having the same facial features as me, how she intends to ruin my life, that my anger towards my counterpart explodes. Before I know it, I have reached out and now my right hand is stinging after having punched her hard across the face.

Anti-Quinn doesn't even seem fazed. She scratches her left cheek with a finger, and brushes it off. She turns her gaze directly onto my eyes, and her hazel-green eyes were so grey I feel a sudden surge of fear spike in my body.

"You do pack a bit of fire for a sweet little girl like you, Barbie," Anti-Quinn tilts her head. "But you really have to try harder." And then she swings with so much power I am left choking for air on the floor, left cheek in pure agony.

That fucking bitch probably just dislocated my jaw. And the worst thing is I am so discombobulated and in so much fucking pain I can't retaliate.

"You'll never succeed," I croak, wiping the blood away from my face as I sit up determinedly. "Santana loves me. We know each other too well. What we have is so strong, she'll see right through your smug face right away, you piece of shit. You'll never succeed."

"Oh, is that so?" My counterpart raises a perfectly manicured eyebrow with a soft smile as she lifts my head with a lean finger to my chin, cold hazel-green eyes piercing into my soul. "But Quinnie, why would she believe you, if she already thinks you're the clone?"

Oh god, I am soooo far away from my comfort zone writing this one.

I thought this would be interesting despite how niche this story is, so hopefully you enjoyed it too!