Trained Step Sister pt.3

After their parents returned, Mark and Allison wound up not having any time by themselves. Either one or both of their parents was at home at the same time they were, or one of the two of them was working. For the first few days, it was tolerable, but after about a week, it was driving the both of them nuts. Mark was still seeing Julia, but she was keeping him at arms distance on their dates. She would still make out with him, but that was it.
How did this happen? Mark wondered to himself. We’re actually progressing backwards in our relationship!
It was especially torturous for him to go home and see Allison, knowing that she was so close, yet so far from him. She wasn’t helping matters by the way that she was dressing. Her shorts were cut high enough that her ass cheeks peeked out the bottom before sloping gently into the backs of her thighs, and her shirts were cut low enough to display a nice amount of her cleavage, and tight enough to accentuate her curves.
Mark found himself masturbating in the shower a couple of times while picturing Allison and replaying some of their sexual encounters in his memory.
After a couple of weeks of this torment, their parents announced that there would be a dinner party that weekend, and he knew that he and Allison would both be off work that night.
Finally!! Mark thought to himself. But his hopes were immediately dashed when they announced that they were hosting it, and he and Allison were expected to be present to help serve their guests.
He and Julia had hung out the night before, and that hadn’t helped his mood any. As they kissed goodnight, she ran her hand along the crotch of his shorts, tracing the outline of his cock with her fingernails before abruptly jumping in her SUV and driving off, leaving him cursing the darkness.

As he returned home from work the next evening, his phone rang. His step mother was running late, and his dad was still at work: Could he pick up some ice?
Immediately seizing his opportunity, he asked her how late she would be, and if he needed to get anything started for her.
“Why thank you Mark, that’s so thoughtful. I’m only about half an hour late, so I don’t think so. I’ll let you know if I’ll be any later.”
Mark hung up and sped home, briefly stopping for ice. Half an hour, tops.
As he pulled into their drive, his heart leapt. Allison was home!
He raced into the house and began searching for her, finding her in the dining room, arranging place settings.
“Can you believe we have to do this shit?” She groused to him.
He ignored her complaint and spun her around so that her ass was facing him and dropped his shorts.
“Mark, what are you …”
“Your mom is running half an hour late.” He hoarsely whispered in her ear as he undid the button on her shorts and stripped them down to her ankles. Allison didn’t need to be told twice, she leaned forward and placed her hands on the table as Mark stroked his dick once or twice in his hand, and started rubbing it up and down her slit. After a couple of passes, Allison’s pussy started to get wet, and she nodded to him.
“I’m ready.”
“It wouldn’t matter if you weren’t.” He snarled at her as he pushed into her moistening twat. Allison smiled at that. He didn’t need to force her to do this and they both knew it, but she enjoyed the charade nonetheless.
He pumped in and out of her in several shallow strokes, loosening her up before ramming in several times, getting as deep as he could, and making her gasp and whimper. He grabbed her by the hair and yanked her head back, snarling in her ear as he fucked her.
“Take it, take it, take it, that’s right, take my cock you little whore.”
Allison moaned in pleasure, feeling the pressure build up in her loins, ready to be released. Suddenly, Mark withdrew from her and began scrambling for his shorts.
“Shit! I just heard a car!! Get dressed, I think your mom is home!!”
Allison dutifully pulled her shorts back up and straightened the tablecloth that she had wrinkled, before heading towards her bathroom and jumping in the shower, just as her mother walked in the door.
When she came out, she found her mother and step father frantically scurrying about.
“Why were both of you in the shower at the same time? There’s work that needs to be done!” Her mom bitched at her. She glanced at the clock and swore under her breath. “We won’t be ready when they get here.” Her husband placed a hand on her shoulder and gave it a light squeeze.
“Everything will be fine, you’ll see.”
With the four of them working, they managed to get everything set up with time to spare, and their parents heaved a sigh of relief.
“Okay, we’re going to go get ready, you two be dressed when they get here. Mark, no shorts, khakis and a button down shirt.”
Mark rolled his eyes, but agreed. As soon as their parents disappeared, Allison turned to Mark.
“I’m all sweaty again, I’m going to take another shower before people get here.” And she headed towards her bathroom.
As she stood under the showerhead, she lightly rubbed her pussy lips, and pushed them together on top of her clit, giving herself a light buzz as she gently rubbed them up and down, her clit trapped between them.
God, she had been so close when Mark had stopped …
She was awakened from her reverie by the shower curtain being whisked back, and Mark stepping into the shower with her.
“What do you think you’re doing?” She asked him as she smiled coyly.
“Finishing what I started.” He replied as he bent her over at the waist, presenting her pussy at just the right angle to him. Allison wasn’t the only one who had been deprived of their orgasm earlier, Mark had also been close when her mother had returned home, interrupting the two of them.
He took a deep breath and slid his cock into Allison, making them both moan. He leaned forward and whispered in her ear.
“Allison, you have to be quiet, understand?” She nodded her head as he began pumping his cock in and out of her boiling pussy.
Jesus, how did I go so long without him? Allison thought to herself.
Jesus, how did I go so long without having sex? Mark thought to himself.
He quickly built up a steady rhythm, his dick twitching inside of her. He reached forward and cupped her swaying breasts in his hands, pinching her erect nipples between his fingers. He could feel her pussy convulsing around his dick, she was so hot that he was convinced that his dick was going to be scalded.
He felt his balls aching for release when he suddenly heard his step-mother’s voice getting closer.
“Allison? Allison?”
Mark froze as her mom knocked on the door.
“Allison, have you seen Mark?”
Mark choked and stuffed a washcloth in his mouth and bit down on it as hard as he could.
“Allison, did you hear me?”
Allison fought to control her voice as she answered her mother, shouting forcefully to cover her passion.
“Jeez mom, I’m in the shower!”
“Don’t take that tone with me, young lady, I asked if you had seen Mark.”
Allison leaned her head against her arm and bit down on the flesh, stifling a huge groan as she did so.
“Allison?”
“No, I haven’t.