The Queen Mother, Lavendula had encountered this creature before, in her first years of royalty. Back then, the kind rabbit, who is either a disciple of Goddess of Love, Hathor, an avatar, or even form of the goddess herself, came to express her blessing to the mother and her son, as you can see here:
Lavy & Thorn: Rabbit's Curse (art by themadcatter) by NeoShard

This time around, however, Lavy had decided to invite her for some very... intimate matters.

They made sweet love to one another the moment she pulled the bunny with her to the bed. Their tongues met and lips pressed to suck in each other. They occasionally broke their kiss to catch their breath, before getting back at it again. Their bodies were sticky with sweat emitted from the heat of their love making, as well as the environment. They managed to reach orgasm after shaky orgasm, and that was before their crotches met and they used whatever erotic toys they could reach.

The hours passed, and as the sweet smells of the queen and her companion's intense passion filled the royal bedroom.

Lavy was unaware of the strange smoke surrounding them, which would bring her into a fun and familiar predicament once the mystical doe takes her leave....
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The next day, Lavy made her way out and into the town, dressed up and strolling down without a care in the world. Her subjects saw through her new form right away, but her son (entering the middle of his teen years), took a moment before he was able to recognize his own mother.

Turned out her adventures with the rabbit creature, led to this curse... or blessing?
Interpret it as you will.
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Lavy's altered form gave her a certain need, one she felt that only her son could sate as she coaxed him into doing that out in the open. As hesitant as he was, it was difficult sometimes for Thorn to refuse his mother's advances.

More so as she begged him to shove his gifted tool up her backside, since she was literally half his size. She poked at him enough times (or rather licked him) before he finally complied and lifted her up. He was surprised that she was so light but, then again, he was transformed with her back them too.

Immediately, she groaned as her son's rod slid into her ass, hilted up to his now-noticeable knot. It didn't take long for Thorn to move his hips up, bouncing his diminutive mother. Ever the buttslut, Lavy mind was mush as she felt the bone stretch her far more as a rabbit than a skunk. She was able to get her boy to pump her harder than before, wanting more than anything right now to have his growing knot enter into her. Thorn believes this would be next to impossible, but she goaded him anyway. Each jerk has his ball of meat punch the back door of the Queen Mother, with each pounding allowing it to become looser and looser. Thorn could hear his mother's cries as she came from a rough ass railing, and he was close himself. Once more, Lavy told him to knot her, over and over before it finally got the message.

With only a few more thrusts, the prince lifted his horny mother up to his tip and let gravity finish the job while jerking his hips up one more time.

The knot practically lodged through the queen's anal ring with a squelch. Unable to hold his own cries, he howled as his balls contracted and his shaft pulsed, load after thick load, filling his mother's insides, just as she wanted. Lavy came even harder as she already felt full, to the point of excess seed was leaking out of the sealed rectum somehow.

She would be more than happy to stay like this longer if it means experiencing this again.
But alas, nothing lasts forever...
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A moment or two after Thorn pulled his shrinking knot out of his mother's royal behind with a wet pop, Lavy had a strange feeling. Her body was tingling intensively and there was a ringing coming from her; one that even her son could hear; a ringing that became louder and louder, until...

*POOF*

In an instant, she exploded in a cloud of purple smoke and before she knew it, she became her skunky self again, now that the spell wore off. With the return to her normal size and weight, her son could no longer support her and they both fell backwards in a thud.

Thankfully, her soft body was not able to crush the prince's pelvis, but it definitely knocked the wind out of him.

It was a fun experience.