Disclaimer: I don't own anything.

You can take Subject A, divide it by 2, which creates Subjects 2 and 3. Then add Subject 4 to Subject 2.

So maths is like cheating.

The front doors to East High shut with a bang.

And the girl who passed through them seemed to not have a care in the world about the noise that some people would have been complaining about.

She pulled her brown bag further up her shoulder and used her other wrist to wipe away the tears that were falling down her cheeks.

How could he?!

How could she?!

He is her boyfriend, and she's her best friend.

What are we, in an episode of "Gossip Girl"?

She could kill him, like, really kill him. He tells her about the things that they should do together. He goes off into a mood when she says that she doesn't want to have sex with him, so he goes behind her back to her best friend.

And her, she's not innocent in any of this.

She's been her best friend since their were two years old and in diapers. What was it, her own boyfriend wasn't giving her any so she just had to go get some of her best friend's?

Gabriella stopped walking, carelessly letting her bag fall from her shoulder and she barely caught it in her fingers. She sniffled.

She felt a rain drop fall on her face and looked up. Shit, it was starting to pour down. The water drops soon started to fall down more quickly and freely.

The brunette sighed, an aggrevated expression on her face with a frown. Great, now her mom wasn't even coming to pick her up.

She'd just have to walk home in the rain... with no jacket... and in a short skirt. Yeah, because that wouldn't attract any perverts.

"Do you need a ride?"

She looked up, gulp.

How to tell him?

It was Troy, Sharpay's boyfriend. He looked at her from inside his dry car, obviously not seeing her sad face.

Gabriella had only spoken to him a few times at parties, Sharpay's house or what-not. But nothing too serious. At least they knew who each other was though. Realising that the rain wasn't going to calm down any time soon, she nodded and rushed over to the awaiting car where he opened the door for her to hop in.

She closed the door behind her and threw her bag into the back seat. "Thanks,"

He smiled, "No problem. D'you know if Sharpay's gonna be done anytime soon?"

How to break it to him?

"Umm... actually, no. She's really busy in there." She nodded her head.

She couldn't break it to him.

"Okay, do you want me to take you home?" he asked, starting the engine of the car.

A sudden thought came to mind; if Sharpay could fool around with Gabriella's boyfriend behind her back, then she sould be able to do the same. Right?

"Do you want to take me home?" She raised an eyebrow, almost suggestively.

Troy turned his head to looked at her, confusion written on his face, "Uhh... what?"

She bit her bottom lip gently, letting her wet tongue be slightly visible, "You know... do you want me... to go home... or... somewhere else..."

His eyes flickered to her lips slowly and stayed there for a while before travelling back up her face to her eyes, "...I-"

She looked down and sat further in the seat, her short skirt riding up a little so more of her thigh was visible. When his eyes were trailed ahead staring at the road as he drove and though of an answer to her question, she pulled her top lower so more cleavage was in sight.

Troy looked at her again, "Well," he paused for a second, "where else would you go in this weather?"

She mentally rolled her eyes, fluttering her eyes seductively. "Maybe... you could, take me... inside," She smirked, her hand travelling gently from her knee to up her thigh.

He was smart enough to catch on to the second meaning of what she said "inside."

Gulping, "You mean like-"

Gabriella cut him off, nodding her head eagerly. "Pull over." It was an order.

He frowned, "What? I can't just-"

"Pull. Over." Who was he to oblige?

As he moved the car to pull over on the side of the road and turned off the engine, she thought fast.

She'd probably kill herself later for this.

"OK, what do you-"

Breathing out heavily, she reached over to him, moved her hand down and pulled the fly open of his black jeans. She looked back up to his face, a smirk on her lips as she raised an eyebrow suggestively again.

His eyes widened, "Ella-" he stopped himself with a gasp when she reached her hand into his boxers and pulled him out.

Moving himself comfortably in his seat, she lowered her head and her tongue made contact with his tip. "Shit."

She walked into school the next day with a blank expression on her face.

Okay, so Payback: Step 1 was done.

It was accomplished when she gave her best friend's boyfriend head.

As disgusting as it was to her, she felt quite proud.

Opening her locker, she looked herself over in the small mirror that was on the metal door. Seeing the reflection of her boyfriend behind her, she slammed it shut. Turning around, she plastered a visibly fake smile on her face.

"Hey, baby." He leaned in to kiss her but she pushed him away. He obviously didn't see anything wrong.

What she did with Troy wasn't bad. It was just the same as all the things she guessed Sharpay had done with Will. But Gabriella's act wasn't as much.

Will frowned, "You OK?"

"No, and I'm not going to pretend that I am either for your sake. Yours or hers." The fake smile faded and it was replaced with an angry look.

He looked down blankly, "What are on about-?"

"You and Sharpay can continue what you're doing. But you're not going to be doing it behind my back any longer. And if you keep it from Troy for any much longer, I'm gonna be the one to tell him." She told him, marking her point. Not bothering to get books read from her locker, she walked away. Leaving him to wonder about his decisions.

The rooftop was appealing to her right now.

She let out a deep breath, letting her worries wash away.

"You know?" came a desperate sounding voice.

Gabriella looked up and saw Sharpay stood with a blank expression of her face, her arms crossed over her chest.

The brunette frowned, "Yes, I know. What? Are you upset that you can't hide it from me any longer? That you can't keep fucking him behind my back?"

Sharpay rolled her eyes, "Look, that's not what it's like."

"Oh, it isn't? Silly me, I see my boyfriend with his tongue shoved down your throat so I think that you're both carelessly having a good fuck behind my back. But oh, let me guess, you love him? You didn't mean for it to happen this way?" she mocked her, a disgusted look on her face.

The blonde girl glared at her, "Look you don't know what it was like, okay? It was just one time, he was there and I needed someone. It just happened."

"What- and then it just continued?!" she demanded an answer.

"It was- Urgh! We couldn't stop it!" she yelled, shaking her head.

Gabriella raised an eyebrow, "You know what? I don't wanna hear it!" She let her arms fall down beside her, "But I'm just gonna say one thing: You're both going to get what's coming to you. And I'm going to be stood there with a proud smirk on my face. It's like they say, payback's a bitch."

"There is nothing that you do to hurt me." Sharpay told her, pointing at herself.

"Oh, I believe there is. Your precious little boyfriend," the blonde froze, "Yeah, him."

"What? You're going to play Troy?" She asked unbelievably.

Gabriella smirked, "No, I'm not going to. I already have." she turned and started walking back down the stairs. Opening the door, she looked back to Sharpay, a bitchy glint in her eyes, "Oh, and I blew your boyfriend."

I like this chapter, what did you think?

I know the whole car thing was a bit crazy but it fits perfectly.

Reviews please :)

-Jess, xx.