You'll Live to Regret It, Pt. 4 
by Musclehead



Summer was drawing near to an end. Shelley and Nick would be leaving soon
since he was set to start graduate school. He had been somewhat loafing around
most of the summer, rationalizing that he would be working his ass off soon
enough. He spent a lot of time lounging by the pool, something made more
enjoyable every day due to Shelley's ever improving body which she didn't mind
showing off. And since Penny had made herself scarcer due to her practicing to
get ready for the fall sports, Shelley didn't find herself comparing herself
to Penny's physical perfection all the time.

One thing that Shelley didn't show off to Nick was her ever increasing
strength. Nick had no idea how much she was working out because she did it
early in the day before he was up. In fact, when he made excuses about not
working out a whole lot, she was sort of sandbagging him by encouraging him to
relax and prepare himself for fall. He would say that working out once in a
while was maintaining what he had, and she readily agreed.

She was also becoming a little less aggressive when it came to sex, though in
her mind, she wanted to do just the opposite, but she controlled her urges,
waiting until she was ready, sometime after they got back to school. But
sometimes fate has a way of forcing the issue.

It might be remembered that one of Penny's goals for the summer as to seduce
her brother's girlfriend right in front of him. Shelley knew how much Penny
turned her on but kept it well hidden. Still, Penny knew her effect on
Shelley. It had happened so many times, getting both men and women worked up
that she knew all the signs even as people were trying to hide it. One person
who seemed less aware of his sister's effect on his girlfriend, partly because
he was having his own issues with her sexual power, feeling guilty due to all
the incestuous implications.

And so, the day had come, Penny's day as well as Shelley's only Shelley didn't
know it yet. Now it might be assumed that what was about to happen with a lot
of guests around might be frowned upon by the older generation, but it must be
remembered that Mom's physical transformation and freed her from quite a bit
of what might be called sexual inhibitions. It was labor day and the pool
party was going strong.

Both Mom and Shelley were getting a lot of attention for physiques that were
noticeably on a different level than all the other people, many of whom were
reasonably fit themselves. Finally someone asked where Penny was. Everyone
knew that she was now a star athlete and Mom had been giving her a lot of
credit for training both her and Shelley. Almost as if on cue, Penny appeared
from the back door of the house.

She was wearing a sheer wraparound and underneath, one of those slingshot
bathing suits.

Dropping the wraparound on a chair and turning towards the gathering crowd,
the suit accentuated the most perfect lower core imaginable, at once
advertising a conditioning beyond most people's comprehension. Her torso
screamed power from her neck down to the lowermost tip going down to her
crotch. Her tie-ins to her legs were more evidence of her superb level of
conditioning. There were instant boners everywhere as people contemplated the
power that that lower torso might generate in mid-thrust during copulation.

Penny's shoulder to tight waist ration had always been pronounced, and now
with another five pounds of muscle in her shoulders and arms, she was the
living embodiment of the perfect V shape. Her muscular legs complimented the
rest of her magnificent structure and her beautiful breasts, barely covered by
two little straps, thrust forward from a chest now able to bench press double
her bodyweight. And to think she was only going to be a senior in high school.

But Penny was so much more than a physical phenomena who had caught up and
possibly surpassed her life-long friend, Brianna. There was no doubt that she
was possibly that was one of the hottest creatures on the planet, certainly
way beyond what anyone there at the party had ever seen. People were asking
all sorts of questions about how she had achieved such an amazing level of
fitness even as they were drooling all over her, guys and girls alike. She was
very friendly and took it all in with a grace beyond her young age.

But Penny was on a mission and soon made her way over to Shelley, who was
expecting to be upstaged as soon as Penny arrived. Nothing had gone on between
them since that day when Penny had rearranged Alex's view of life. Indeed
nothing went on that day. Yes, Penny knew the effect she had had on Shelley
that day, but she didn't act on it.

Today would be different. Penny made her way through the crowd over to where
Shelley was stretched out on a chaise lounge, having been basking in the
attention she had been getting before Penny's arrival. Standing at the end of
the lounge, staring at Shelley was already enough to get Shelley's juices
flowing, but when she started to seductively run her finger tips sometimes
over the straps that barely covered her nipples, sometimes under, Shelley
could barely suppress the involuntary moans escaping from her lips.

And then, from the side, "What are you doing, Penny?" screamed Nick. She just
ignored him and continued her seductive moves, swaying her powerful hips,
licking her lips, playing with her breasts. "Get away from my girlfriend," he
yelled as he ran at her, plowing into her and knocking her down to her side
with him on top as people moved instinctively out of the way. Although he had
the element of surprise, showing her amazing athletic ability, Penny somehow
grabbed ahold of his arm as she fell.

She rolled in the same direction and with that concentrated explosive energy
and power, she flung him over her and into the pool more than five feet away.
She was on her feet and back in front of Shelley quickly, but moving closer,
straddling the lounge chair as Shelley sat up. A few seconds later, just as
Penny was leaning forward toward the panting Shelley, Nick was back, with a
new tactic. He wrapped his arms around Penny's waist from behind to pull her
away from his girl.

Penny just straightened up and stood there proud and strong, her shoulders
back, smiling down at Shelley as he tried in vain to move her. Then she peeled
his hands from around her waist, pushing them back, pulling them together
behind her. She leaned forward, Nick's futile attempts almost un-noticed.
"Pull my straps aside, Shelley." She reached forward toward the goddess's
magnificent breasts. "With your teeth."

Nick was going crazy at the notion that his sister was seducing his
girlfriend, and doing it right in front of him. But it was even more
humiliating that she was doing it in front of all their friends and he seemed,
at the moment at least, powerless to stop her. Could it get worse? Well, yes.
As Penny began moaning along due to the wonderful oral gratification she was
receiving, Nick redoubled his efforts still getting nowhere.

And then, Penny removed one of her hands, reaching forward and cupping the
back of Shelley's head, pulling her in closer as she held Nick locked with one
hand, and behind her back no less. Soon, both girls were making quite a bit of
noise, Shelley at least as turned on as Penny even though all she was doing
was pleasuring this goddess. Nick was struggling furiously with no results,
but becoming a bit of an annoyance.

Penny suddenly thrust back with her hard ass, knocking Nick onto his back on
the lower end of the lounge, and then sitting on his stomach, catching his
hands under her. The she reached forward and grabbed his ankles, twisting his
lower legs down then back before putting her powerful legs on top of his so
she caught his ankles back near his hips. He couldn't move anything. With her
hands now free, Penny reached forward, pulling Shelley's head back into place
with one hand and reaching down with the other to find Shelley's pussy.

Nick was yelling curses at Penny, as frustrated and embarrassed as he had ever
been, so completely controlled by his younger sister, unable to move anything
except his head while she ignored him and played with his girlfriend's pussy
as she licked, sucked and fondled Penny's breasts. Everyone watching clapped
and shouted as the girls reached simultaneous orgasms. And to add to Nick's
embarrassment, he ejaculated into his swimtrunks at the same time.

Penny got off him and stood back away from the chaise longue as Nick got up
furiously came at her, only to find himself on his knees with both arms behind
his back in seconds. "Give up Nick. I could take two of you. I'm too strong
for you and too hot for your girlfriend. Evidently too hot for you as well."
She let go and he got up and hurriedly went into the house as everyone laughed
at his expense.

A little while later Shelley found him in their bedroom, sitting on the edge
of the bed staring down at the floor. When he saw her his anger again boiled
to the surface. "How could you do that? How could you humiliate me like that?"

"I couldn't help it. She's soooo hot. It was almost like I was hypnotized. And
she controlled you like you were a child. She's so much stronger than you."
Shelley almost swooned as she talked about Penny, further enraging Nick.

"Well I'm still stronger than you." He lunged at her, knocking her to the
floor and pulling at her bikini, tearing the top off. It was almost as if he
was trying to rape her. His day was only about to get worse. Shelley pushed
with all her might, dislodging Nick. Before he could react, she was on him,
forcing him onto his back as she intertwined her legs around his. She slammed
his wrists to the floor on either side of his head.

He struggled wildly, but the moment had arrived. "I'm stronger than you now,
Nick. Not just pound for pound. I'm stronger, period. You've been taking it
easy all summer long I've been working out like crazy with the help of your
sister's training." Shelley was all but panting, even more turned on by the
new found revelation that she was stronger than her man than she had been by
his sister.

With lightening quickness, she turned around, caught his arms under the folds
of her knees and slammed down on his face. After pulling her suit bottom to
the side, her drenched pussy found his mouth. She leaned forward and grabbed
his legs at the ankles then sat back up, folding him in half. "Start licking,
buddy boy." She started undulating her hips on his face but she wasn't feeling
his tongue yet.

"I said lick," she commanded as she pulled back farther on his ankles, pushing
them out to the sides as well with her strong arms. Suddenly a tongue went
deep into her pussy, sending her into instant convulsions as she thrusted up
and down on his face with more frenetic energy than ever in her life. Oh this
was so fucking awesome. It was just like Penny and Mom had said. It is so much
better when you make him do it then if he does it voluntarily.

She rode his face for half an hour, at one point letting go of his legs for a
few seconds. As his body flopped back down onto the floor, she noticed that
even through his swimtrunks, she could tell that he was fully erect. Yanking
his shorts off, she saw that he was decidedly even harder than usual. Through
her sexual fog she realized that he was enjoying being sexually overwhelmed as
she was doing it. She grabbed his ankles again, spreading his legs out to the
sides as far as they could go, eliciting a cry of pain from poor Nick into her
pussy and sending her on to a new sexual high.

Leaning forward, she began rubbing her breasts on his cock. It only took about
two seconds for Nick to explode all over her tits and her tight abs. She got
off him and turned around, straddling him on all fours. "Lick all your cum off
my beautiful tits and tummy." He resisted. Leaning farther forward and down,
she suddenly started slamming her hard abs up and down on his head. It was
amazing how much force this not real big woman could generate with her well
trained torso.

"All right, all right," he cried. "Please stop. I'll do it."

"Make sure you linger and get my nipples real clean, understand." As he
dutifully cleaned her off, indeed taking extra time on her erect nipples, she
impaled herself on him, again pinning his wrists down to let him know that
from now on she was in charge because she was stronger. From this day forward
Nick's life would be subservient to a smaller but superior woman. And to think
that this sequence of events started years before when he teased his sister
and her friend, Sheila, now known as Brianna.

And as to Penny and Brianna, whom we hadn't seen for quite a while, well they
got together on occasion for some awesome muscle girl lovin', but mostly when
they weren't working out, they spent their time doing whatever they wanted
with whatever guy they wanted, taking sexuality to new heights, because they
knew that it was always better when you can make the men do it.