Xavier had had a long day. School was pretty tough really, more than usual, and all he wanted was to get into bed and rest after all of it. Seems his sister had even beat him to it, already resting in her bed, her head peaking above the sheets, an ear flicking every now and then or a cute little noise maybe. He eased into his own bed on the opposite end of the room, yawning softly and getting settled underneath them himself with one more sigh of relief, the warmth and comfort more than enough to bring him to sleep within moments. 

The night quickly became peaceful, with even their mother had long been asleep for a bit now, but just because it was peaceful in the house, didn't mean that Xavier's dreams were going to be the same way. Not by a long shot, the thirteen year old cheetah tossing and turning subtly in his sleep for the first time since he had been young, images showing in his mind that he couldn't really make too much sense of. Sure, he'd seen these things before, but he didn't remember feeling this way about them at all. 

He saw many different women, mostly that he'd seen on the internet, and... Breasts, naked bodies, smooth forms that had never really sparked much interest in him before. He gave the slightest of groans out into the room even out of his dream, his sister turning in slight disturbance, yet not yet waking from her own peaceful sleep, a mass rising in his sheets slowly but surely as the dreams went on.

And they went on and on, not proving to be any less arousing for the poor thing, starting to appear as if he were there and actually touching, feeling, playing with those women... And yet also his sister? There was a slight feeling of conflict within him about that, but in his dreams, his conscience wasn't strong enough to restrict him. His hands roamed over her fairly well-developed form even for her age, feeling up the breasts he'd always secretly wanted to, feeling so real...

And outside of his dreams, the most peculiar thing was happening, that rising mass kept rising for a few moments, far beyond the few inches that he knew his member could reach, thickening and curving off, sliding down the sheets and over his leg to make another bulge, a couple inches in width, and continuing to lengthen with each and every moment.

He was giving the slightest of soft moans in his sleep, his sister unknowingly in an increasing state of unrest, as she laid out on her back and spread her legs as her tired mind tried to search out a more comfortable way of sleeping, the mass lengthening onto the floor, thick and black, throbbing and moving slowly, silently, off toward his sister's bed. It was on its own mission, and it knew what it wanted, even if he was somewhat wary of it. 

It covered the distance faster than it should be able to, but its impressive length was more than enough to allow it to traverse wherever it happened to want to within the room. But there was only one place that it would ever want to be, and the sister was soon made a victim of that want, a thick, black cock head rubbing against her ever so rude panties protecting her womanhood, her ears folding back as she started to give her own soft, high pitched moans out into the room almost in tune with her brother's. 

And his dreams were gradually turning more and lewder in nature as well, as the events of the outside world unfolded the inner became far more perverse, and far faster too. Like imagining his sister as a much more well-endowed woman than she actually was... And himself as something similar, and yet so different. Strong and masculine and far, far too hung. And all the while, he and his sister were having hot, passionate love in his mind, precum wetting the tip that was poking around her sister's treasured area, making it all the easier to slip around those panties to get to where it needed to go. 

She squirmed and whined softly in her sleep, she'd never been penetrated before, not even once, so this was an experience she'd never had, starting to stir slowly from her rest as it pressed again and again, short thrusts prodding past her lips and into her sex the impressive girth of it making it a slow process of working itself deeper, but that was best, as the slower it went, the less it woke her up, and it wasn't done yet, that was certain. 

There was only so much that could be taken of such pleasure though, the sister cheetah slowly stirring and yawning softly, soon catching that it was still quite late in the room groggily, just before she felt the odd sensations in a place that definitely, definitely shouldn't be having odd sensations inside of it. The pleasure was slight, very much so, but because the member had managed to bury itself nearly cervix deep within her already, every little movement meant she could feel it working nearly the entirety of her pussy with ease, making her bite her lip and suppress a moan as she gazed with wide eyes over the intruder inside of her. 

Silent screaming rang out inside of her mind, all so eager to pierce the room and yet she refrained from it, fear abound and yet a strong sense of curiosity as well, letting her eyes follow the shape in the dim moonlight, just barely reflecting off of the sleek surface of the long, black tube of cock flesh that laid across the floor, leading her to her brother's bed. The girl slowly rose to follow it herself, the shaft giving a sudden thrust and spreading her cervix open itself, making her lose her balance with another, somewhat louder moan, on all fours as she collected her bearings from the event.

For once in a long while in the room, there was complete and utter silence, no movement,  nothing at all. The girl steadily but surely continued her approach as her brother took small, steady breathes, his dreams and his lust seeming to momentarily subside as she did so, the lightest of sparks of pleasure from her body's movement. Each step incited a little more for them both to experience with how they were so well connected. The sheets were lifted by her tentative paw to reveal just what she could only have suspected was the case, even if she didn't believe it. 

The slick, massive black cock was just so alluring to look at, and it made her spine shiver in a multitude of ways. Both by actual pleasure and the thoughts that ran through her mind of what such a unique member could actually do, and what it was already doing without him even having had a conscious thought put into it already. It wasn't just the shaft that was impressive either, he had a large, full sack that no doubt had more seed than any male around several times over, big enough she couldn't palm them, and she did try as she crawled atop the bed. 

The ever so depraved dreams kickstarted again the moment he could feel the warmth of his sister against his own, completing the feeling of her already every so tight womanhood around that member of his and making it feel all the more real within his mind. All too real, the shaft making sudden and quick thrusts again and again as he did the same to her within his dream, the room filling again with the sounds of moan after moan of the siblings. It would twist and explore her depths as much as it liked, showing her a taste of just what she had been dreaming of, the cheetah in constant and far too intense pleasure moment by moment, and her brother was a victim of it all the same. She could almost hear the seed in those tanks moving and getting prepared as she was made to brace herself against her brother and hold him tight, almost adorable if it weren't for the fact that this was far beyond innocent. 

The uniquely cocked cheetah boy gave out a loud moan, enough to pierce the walls quite effectively as his eyes shot open to see his sister atop him, thoughts racing to as a thick bulge raced up the urethra of his shaft, even as it still pounded her so mercilessly into him, watching his own shaft be far out of his control was such a strange experience. It was so wrong, this was his sister and he was so deep inside of her, and he couldn't deny that he was very much enjoying it as well. 

The girl could feel a heavy amount of leaking within her, it was a building pressure and warmth, she could almost see her belly pushing out as her womb was filled with so much of nothing but the last bits of precum. And then the climax hit her, making her gasp as powerful gushes of cum started erupting inside of her time and again, moaning out loud and catching the drowsy ear of a certain mother cheetah. 

The curvaceous woman slowly awoke, hearing the clearly sexualized moans of her two children through the walls with a bit of a sigh, straightening herself and bearing an expression that said all it needed to, bearing the weight of such information for so long meant she wasn't all too surprised by this. What she was surprised by was the massive belly her daughter had earned by the time she pushed the door open, a gasp of surprise from both teens as and the deepest red blush that they could ever possibly muster, looking an almost amusing orange when the fur was taken into account. It was a massive belly, pushing out and looking beyond pregnant, full of nothing but what she could assume but her son's own virile production. 

"Sooo... This is a bit awkward, yeah I know. But there was going to have to be a time I had to explain this to you anyway, and now that it's staring me in the face I don't have much of a choice now do I?" She sighed softly, rubbing her temples and refreshing her mind over all the topics and giving a slight nod as her children took the time to muster what words they could for a situation. 

"Am I in trouble for this?" The sister spoke first with a deep red blush. Unbeknownst to her, the only slightly curvaceous breasts she had been gifted with by her generous mother were starting to press out even more against her nightwear, quite impressively indeed, yet her mother merely made note of that... Hadn't been the first time she saw something like that in action after all. Inch by inch the cheetah girl's breasts pushed onward, little by little conquering her chest and laying atop that already well bloated belly of hers, making her look almost like some kind of fertility idol if it weren't for the fact the rest of her form didn't quite fit the bill. 

"No, you're not in trouble, neither of you are in trouble. You couldn't have known about this, so the responsibility here is entirely mine really." She nodded, grasping her tail and playing with it herself as she tried to think of a way to diffuse all of the awkward tension of the situation. It didn't seem possible. "But son, there's only one real way to say this, and I know you're going to have a hard time believing this, but it is completely true. You are part of an alien race, at least in part. Rest assured that I'm still your mother." She spoke calmly and clearly, watching the expression of shock on her boy's face widen a little more with each and every word she spoke, it was almost comically cute, bringing a bit of a giggle out of her as she watched it happen.

"So... This is natural?" He asked back, almost sounding a bit relieved... He did have an explanation, as odd as it was, it was better than nothing at all, and he'd take whatever solace he could get in the strange place he was put in right now. Not to mention he was bound to blush all the deeper as his gaze turned to his sister, noticing her breasts being so much larger than they once were, bigger than his head and just so enticing to him. He always had a thing for large breasts. Now if only her breathing wouldn't make them jiggle a little every time he could focus more on the conversation at hand... And keep his lust in check. This was tough though, especially because even he could tell they were still pushing out, and his sister couldn't help but give soft little moans every now and then as they pressed taught against her clothes, straining them a little more with each passing second. 

His mother was more than happy to help him out though, nodding in agreement as her tail slowly made its way out of her grasp. "It's natural for you, yes. You're not a freak, at least, not a freak as far as being naturally different because you're not all cheetah in blood, anyway. Besides, none of my children will be called freaks." She huffed with a bit of pride, averting her gaze to the happenings as she didn't want to make them any... Well... More uncomfortable than this had already been. 

"So you're telling me that all this is just... Normal for him? Everything? Even the huge and long... Yknow..." She breathed quietly, blushing deeply and trying to hide her face somewhere, finding a mild success in doing so by hiding it between the massive breasts, making the quiver and the boy beneath her do just the same, a slight movement of the length inside of her making her eep and moan softly as his lust was spiked by such a display. They wobbled and swayed a little bit, only restrained by the now protesting and subtly tearing fabric, cream-colored cheetah furred flesh poking out from the holes that were starting to be created. 

"Completely normal for him, trust me, I would know. He hasn't even fully developed yet though." She calmly remarked, starting to flip through contacts on her phone. The mother cheetah had to get some countermeasures put into place, and soon, or else things might get a little out of her control too fast. With the sound of more moaning coming from her daughter as that member started to thrust yet again into her, she knew she didn't have all that much time to get this done either, flipping through her contacts and finding the exact one she needed, dialing them up and letting out a brief sigh of relief as she tried to ignore the burning lust she was feeling, oh she'd love to feel that pleasure again...