Pain, Humiliation and Family Love.

Athena whistled to herself as she opened the front door to her home and began walking towards the stairs to reach her room when a rough hand grabbed her by the shoulders, "And what do we have here? Skipping school Athena?" The ugly chuckle told Athena everything she needed to know.

She turned her head slightly to the owner of the hand, her older brother, Brian, "Get lost Brian, I have stuff to do." Athena was glad her clothing was hiding her new muscles and tits, she knew just how jealous her brother was of other people matching his physique or beating it. Of course, whenever he got shown up by the other guys, he would take it out on her.

Brian snorted, "Yeah right, now come here, we're going to spar." Athena suppressed a sigh, looks like he got shown up again, and that meant she was going to get beaten up again. But not this time, Athena though, she knew that she was now much, much stronger that she appeared. She had tested her strength on the way home and found that her muscles weren't just bigger, but denser, which meant she could punch hard as she allowed Brian to drag her down to the basement where a professional boxing ring was set up.

Dad was a professional boxer, now a training instructor for boxers and he started the two on it as a way to keep in shape and in his own words, 'work out their differences by beating the shit out of each other' and Mom had accepted it, but then woman ruled the rest of the house so Athena supposed it was just one of those allowances that Mom made as they reached the ring.

"What the hell? Where's the gear?" Athena asked, realizing with a slight chill that Brian might want to do this barehanded, and the last time he **** her into a barehanded spar, she had two broken ribs and a fractured forearm. Her fear was realized as Brian simply called out angrily for her to enter the ring, Brian wanted to really beat her again.

Athena's eyes narrowed. Fine, if Brian wanted to cause some Pain, then she would pay it back, with compound interest as she climbed into the ring and took her place at opposite her brother, "So, any reason you want to beat me up this time?" God she hated it when Brian tried to assert his dominance because someone had bigger muscles than him, or a bigger dick, or was smarter than him...anything could set him and while Dad had stopped one or two attempts, he had thought Brian was overly-enthusiastic, and Athena knew that Brian was good at hiding the evidence, otherwise Dad would kick him out without any hesitation.

Athena smiled grimly as Brian shouted, "Just shut the fuck up and put 'em up!" Tch, probably lost a fight, but Athena readied herself anyway, ready for anything. Seconds later, Brian surged forward and Athena shifted as his fist clipped her forearm and she felt the impact and a slight sting, 'I barely felt that. Am I tougher as well? Makes sense, Liz was fucking stronger than she looked, so she'd be tougher as well. Okay, focus! You're tough, not invincible! Just make him back down!

The two siblings danced around the ring for several minutes, Brian sending punches that Athena dodged, before he landed a hit and the girl grunted in pain as Brian grinned, "That was just a love tap!" He landed several jabs and sneered, "Pathetic!"

Athena stayed calm, feeling the dull ache of the punches she had been blocking for the past few minutes, before she weaved out of the way of a punch, and met another one coming straight at her face. With a sickening thud that drew blood from her cheek, Liz stumbled and Brian pounced, raining punches down on her as Athena tried to block and deflect most of them like she had been taught.

"Hah, take that you bitch! Fucking teach you to be so fucking happy!" Brian snarled as he flexed his fingers and hands, as Athena slowly stood up and glared at him, "What? You going to cry?"

Athena decided that she wasn't going to take this anymore. She had a girlfriend, or at least a possible girlfriend, who could make her bigger and stronger by fucking her. She had been fucked twice by a massive cock and grown this big, and while Brian was too busy gloating to notice the change in height, he wasn't so into it that he missed Athena taking off her jacket to reveal her new body, "What the fuck?"

Athena remained silent but flexed visibly, watching Brian shake in fury, Time to fuck you up.

As Brian charged, Athena took up her stance again and this time dodged the wild swing before replying with a punch that created a sickening crack and Athena saw teeth and blood fly, but didn't let up.

Unlike the barrage of punches he had used, Athena's attacks were precisely aimed, and powerful enough that the sharp crack of breaking bones could be heard with every impact.

Finally, two simultaneous punches broke his arms and Brian collapsed from the pain, cursing breathlessly.

"Fucking bastard, that was for six years of your shit." Athena snarled, before she decided to humiliate her brother further and knelt down to unzip his pants, pulling out his flaccid penis as Brian stared at her. Athena didn't even look up as she engulfed it in her mouth and began sucking, licking and nipping it, feeling it swell until it was fully erect.

With that done, Athena followed her instincts and a few videos she had seen, one hand fondling his balls and the other stroking what wasn't in her mouth and even as Brian cursed her, she knew that he was close.

Finally, Brian groaned and she felt his dick spurt into her mouth, but rather than swallowing, Athena sucked as much out as she could, and then stood up with a mouthful of cum.

She walked over until she was standing over him and Brian snarled at her, "Like your meal bitch?"

Athena's response was to spit the mess in his face, before calmly saying, "Find another sibling to beat up." She turned to leave when she saw who was at the top of the stairs, "Dad?'

Brian paled as their father looked down at them, and then said, "Brian, I'm going to speak with your sister, then I'm going to call the hospital. When your mother gets home, we'll arrange for you to move out. Athena, could you come upstairs?" Athena nodded happily and bounced up the stairs and followed her Dad into the kitchen, where he poured a glass of water, "You better rinse."

Athena nodded and gargled, swirled the water, and then spat it and the remaining cum into the sink as her Dad took a seat, "I had suspected for a long time, but I was never able to get proof. If I hadn't come in just then...Athena, I'm so sorry."

Athena quickly crossed the space and hugged her dad, "It's okay Dad, Brian's just a fucking asshole who got good at covering his tracks, and making sure I was too weak to resist."

Her dad smiled weakly, "Thanks baby, but damn, you haven't been using steroids have you? Because I know you weren't this big yesterday."

Athena smiled weakly, "It's a long story."

"I have time."

Athena nodded, "Okay, it was actually a few minutes ago at school..." And with that she explained about Elizabeth King and how she had sex with her twice, growing her muscles and breasts each time. To her relief, her dad was even a little proud at his little girl starting her first relationship, but she was also confused why he wasn't surprised to hear about Liz.

"I've seen it in the business, it's a very rare genetic condition, inherited from Mother to Daughter though it can go dormant, that causes a girl to grow a penis and every time they masturbate, they release a flood of hormones that trigger the growth." He shrugged, "And the effect on you is mostly a side-effect of having sex with her."

"I won't grow bigger will I?" Athena asked, slightly worried.

Her Dad shrugged, "Biggest girl I know is close to seventeen feet but she was an **** case, plus the growth is slow, so you'd have to be having sex with her every..." He gave Athena a flat stare as she whistled innocently, "Just be careful, once you stop growing, then she can get you pregnant very easily."

"I'll be careful Dad." Athena replied before looking at the house, "I can't stay here Dad, not for a while, not until I know that Brian is gone. I'm going to pack my stuff and stay at Liz's until then."

Her Dad nodded, "I understand baby, you just be careful." He glanced down at his hand as Athena laid hers on top, "Athena?"

"Thanks dad, Love you tell mum I will visit soon" giving him a kiss on the cheek then picking up her stuff and walking out with a smile.