Jenny is insatiable, of course.

Marcus lay limp as his sister sat on top of his face, her hot, dripping pussy still pressed over his mouth. Even if he found the courage now to try and tell her how he felt, every word would end up muffled. She wouldn't even hear him.

"Wow little brother." She gasped above him, still panting for breath. "You're so good at that. Fuck...I'm going to be using that sweet tongue of yours a lot. Don't worry, we can still play plenty with your cute little dickie, but sometimes a girl just needs to feel her lover licking her and know he's focused only on pleasing her." She shifted up onto her knees above his face, and for a moment the young prince felt a flicker of hope that this was over and she was going to get off him. Jenny promptly crushed that, swinging her leg over him and shuffling round so that she was facing down his body instead, her muscled butt hovering right over his face. Those two, pale cheeks were all he could see, perfectly smooth and curved, and Marcus felt, to his horror, his aching dick start to twitch and throb. It even stiffened up a little, sending shivers through his throbbing, overly-sensitive skin. He blushed furiously, hoping Jenny wouldn't notice, but of course she did. "Oh, you like my ass, do you?" His sister purred above him, her voice hot with satisfaction.

"Jenny, wait!" Marcus tried to say. Then she just sat back on top of him, reducing his voice to a muffled squeak. She bucked back and forth, rubbing her hot pussy over his chin again and moaning. Every time he tried to push her off she just sat back down harder, too much for his feeble little body to even try and lift. Pressed underneath her butt, all he could do was watch in shock as she reached back with her hands and spread her tight cheeks. Her butthole was right there, a tight pink ring of muscle, hairless and clean. Marcus just stared at it, frozen under his sister. He had no idea what was going on, but his body flushed with that same tingling heat.

"Come on now, runt." He heard her say, a note of impatience in her words that made him tremble anxiously underneath her. "I did it for you and it felt good, didn't it? Now it's your turn. You're not going to be a selfish lover, remember? Lick my ass and make sure I know you mean it." She sounded a little scary. Marcus didn't want to do this, but she was right that she'd done it to him and it had felt good, no matter how embarrassing it had been. Maybe if he just did what she said she'd finally get off him. He took in a deep breath, then stuck out his trembling tongue towards her butt, craning his neck to reach.

Jenny let out a hoarse, gasping moan as he licked up the ghostly-white skin of her butt. At first he told himself he'd just lick around that hole and hope that would satisfy her, but she kept bucking and moving, clearly trying to get his tongue exactly where she wanted it. His tongue fluttered over that tight ring of muscle and he felt it pulse and wriggle against him. He knew his face had turned scarlet the moment he realized what she wanted him to do, but no-one would see how hot he was blushing with his sister's buttocks pressing against him, smothering his scalding cheeks.

Jenny's breaths grew hungrier with each tentative lick, and Marcus felt his own body respond despite his ****. His belly fluttered madly each time she clenched and moaned, knowing those hoarse sounds meant he was pleasing her. One of her hands was back in front of her now, and he realized the wet, squelching noise he was suddenly hearing meant she was furiously fingering herself. Her tight butthole twitched and relaxed when he licked her, like it was trying to pull his tongue inside. He blushed even hotter at the thought, but a strange part of him wondered what would happen if just he let it happen? Would Jenny like that even more?

"Get that tongue inside me, little brother!" Jenny squealed above him, like she'd heard his thoughts. Too far-gone now to resist his sister, Marcus pressed his trembling tongue against her butthole. He felt the tight ring of muscle tense up, then suddenly relax, and just like that he was back inside her. It was really hot there too, and he could feel muscles clenching around his tongue. Utterly unsure what he was even doing, Marcus just thrust his tongue in and out the way he'd pleased her pussy earlier. There was a strange musky flavor on his tongue, different to her pussy but still not at all unpleasant. He could hardly even think through the haze of glowing embarrassment, shameful arousal, and on top of it all, this new, tingling desire to keep going and see what happened. "Fuck, fuck fuck!" His sister screamed suddenly, even louder than the last time.

Her butthole clenched so tight he felt like it was strangling his tongue and he squealed shrilly, pulling back before she hurt him. His tongue hang from his lips, aching and tired, as he watched his sister thrash and gasp her way through another orgasm above him. Through it all, Marcus knew he should be disgusted and ashamed at what he'd done, and he was, at least a little. At the same time, he couldn't help but feel a strange satisfaction knowing that he'd managed to make her feel so good.

Jenny was really beautiful. He'd known that even before, of course, but as she slumped off him to one side and lay there gasping on the bed, he felt his gaze drift over her half- naked body, pale skin coated in a sheen of sweat. It felt like he was seeing something different now and he couldn't look away. Her long, muscled legs looked so perfect, running up to the curves of her thighs and butt. Lost in this strange haze, Marcus found himself struggling with urges he'd never felt before. Some part of him, fluttering in his belly and throbbing in his aching dick, wanted to do that again, make it even better this time. He even wondered for a moment if he could make her orgasm just from her butt, without her having to use her fingers at all.