They give her a taste of the infection

Parker looked at the intruder with a vacant expression, before deciding to ignore her for the fucking he was giving his sister, and how close they both were to cumming.

Rachel, on the other hand, was intrigued. She spoke to the girl, her voice continuously interrupted due to dicking she was taking. "Ohhh... OHHHH... looks... looks... looks like we.... OOOHHHH.... OOHHHHHH YESSS.... we have a .... fan! And she's hot too." Rachel winked at her.

"She's... not... hot.... you're hot sister... you're so hot... you're my hot sister... SOOOO HOOOOTTTT," Parker moaned, the virus having robbed him of any intelligence that didn't involve rutting her. He jerked up Rachel's body so they were both standing while fucking.

"OH BROTHER! YES! KEEP HITTING ME THERE! YESSSS!!!" Rachel cried, as she moved her hand to stroke her clit in time with the thrusting dick.

"You guys are siblings?! What the fuck is wrong with you!?" the girl screamed, absolutely disgusted by the display in front of him.

Parker paid this absolutely no attention, but Rachel giggled again through her moans of ecstasy. "Jealous... sweety? You a... VIRGIN? OOHHH YESSSSS! HNNNGGGGG!!! You want a taste of... HOW GOOD THIS FEELS?"

Rachel started stroking faster, as her giant breasts bulged even more as they filled with milk. As if on cue, Parker grabbed her jugs hard enough for it to spill out, all over the store.

A few drops splashed right into the girl's face. "Ahhh... gross! What the fuck?"

But neither sibling was paying attention to her anymore. They were both about to hit their limit.

"OH PARKER! I'M COMING! I'M COMMING!!!"

"SOOO HOOTTTTTT!!!! SO HOTTTTTT!!!"

The two siblings screamed in primal ecstasy. Parker blasted what felt like a year's worth of spunk into his sister's climaxing pussy. Neither of them had ever had an orgasm this good... and it just kept happening. It wasn't stopping... just getting more intense... more mind shattering.

The girl, meanwhile, had enough. She ran from them, out the gas station door, trying to put as much distance as she could from those freaks.

She ran about three blocks before stopping to catch her breath and process what she had seen.

"What the everlasting fuck was that?" she asked to the empty streets. She had seen all sorts of freaks working at the gas station, but never anything like that.

"Screw this job. I don't get paid enough to deal with this shit," she said to herself.

She turned to start heading home, wanting nothing more than to just forget about all of this. But she couldn't get the image out of her head. How impossibly huge that slut's boobs were... how much milk she was firing... how loudly she squealed...

"God I wish that were me."

It took her a moment to realize what she just said. It just sort of slipped out. She shook her head in disgust, trying to get the thoughts out. But no matter how hard she tried, more dirty thoughts filled her mind.

"I want boobs like that."

"I wish someone could rut me like that."

"It must feel so good to shoot so much milk."

Her face reddened with arousal as the fantasies consumed her. "Maybe... maybe I can take... one more look..." she said to herself.

She began walking back to the gas station, her lust slowly increasing with each step. As she moved, her hips slowly started to sway more seductively. As she got closer, she found her body heating up, and slowly began removing articles of clothing. By the time she reached the door, she was totally naked and felt no shame in being so.

Looking through the window, she could see the two siblings.

It seemed like they were taking a break from vaginal sex. Instead, Rachel was covered in cum and posing seductively, while Parker was standing a few feet back to get a full look at her, while furiously masturbating.

The girl swung the doors open, causing Rachel to look at her. Grinning, Rachel winked at her and gave her a peace sign. "Well look who's back. Ready to join the fun?"

"Yes! Oh god yes! I need that dick! Please fuck me! Breed me! Make me into a milking milf!" the girl pleaded in desperation.

Parker looked up at her vacantly, feeling a twinge of arousal for this new naked girl. However, he also saw his sister, whom he found far more attractive. Compared to her, this slut was nothing.

"No! Gunna... fuck... sister again when done... jerking to her! Go away!" Parker grunted.

The counter girl gasped. "No! Don't you want to fuck me too? I'm hot, aren't I? Don't you want these titties?" she begged, squeezing her breasts together and wiggling her hips to try and seduce him.

"Not... as hot... as sister..." he stammered.

Rachel looked at her brother in surprise, not understanding why he wouldn't fuck as many people as he could. But she didn't understand. The virus had gone overboard on making him obsessed with his sister. He would never get tired of her. If there was ever a choice of who to fuck, he would pick her every time.

At hearing this rejection, the counter girl felt a jealously she couldn't quantify. She needed him to fuck her like his sister. NEEDED IT!