In all the excitement of this brave new world they had entered, Derek and Sonya barely noticed the passage of time until it really was late enough for them to go to bed. Sonya wasn't interested in a sexual experience right now and Derek was enough of a gentleman to respect that; he excused himself to the bathroom for a while and let Sonya explore her new body for a bit in private. After that, Derek was tired and Sonya was enjoying this form enough that she wanted to stick with it for a while, so they agreed to hold off on any more transformations until the morning. That meant Sonya would get a chance to fulfill the highest purpose that any stuffed animal could: to be something to cuddle with during the night.
It was only after Derek switched the lights off and wrapped his giant arms around her that Sonya realized she didn't feel tired at all. In fact, she felt as awake and alert as she ever had, and it occurred to her that she might not actually be able to sleep anymore. But that didn't mean she was getting bored, lying still in the dark like this. She was exactly where she was supposed to be, a sort of protective force, responsible for making sure that Derek would have nothing but sweet dreams. The thought stuck with her, repeating over and over in her mind. Sweet dreams. Happy dreams. She was trying to project that energy into her boyfriend's subconscious, as though she had any idea how to do that. But now that she knew magic really existed, anything seemed plausible.
Suddenly, she felt what seemed like an earthquake jostling her. Derek, who had been sleeping on his back, rolled over onto one side and unconsciously pressed his teddy bear girlfriend into the space between his ribcage and the mattress. The sudden shift of weight on top of Sonya flattened her plush body a little bit, and she had hardly adjusted to her new position when she heard a soft voice breaking the dead silence of the darkened room. "Sonya..." Derek slurred. "I... turn you... to... bear..."
Sonya was curious now. Was her imagined dream-power actually working on Derek, or was this just a coincidence? Near the tips of her flat feet, she could feel Derek's erect penis slowly encroaching upward as he slept. That was not what she meant by "happy dreams"... At the same moment, she could feel Derek's weight on her pressing tighter and tighter, as the space underneath his body seemed to get smaller. Sonya thought her boyfriend was just shifting his position again, but looking around, he and the bed and the whole room seemed to be getting smaller as well. She could feel her heart beating again, a sensation she hadn't entirely realized was no longer there. Was the transformation wearing off now? Was she becoming human again? And why exactly did that thought disappoint her so much?
But it was immediately obvious to her that her changes were not reversing, at least not exactly. Her stubby arms were losing their soft, rounded-off shapes, but instead of fleshy fingers poking back out, she was gaining new sharp-tipped claws. As she grew more and more in size and strength, she gently tried to peel Derek off of herself without waking him, and found that even though she was still less than half his height, she could lift his full weight easily.
Sonya didn't quite understand what was happening to her at first. Then, after a moment's thought, it occurred to her. She was still wearing the collar! And that meant her body was going to literally obey any transformation command it was given, even if it was a half-formed sentence that spilled out of an unconscious mind.
Derek woke when he felt hot breath in his face. He had been in the middle of the most wonderful dream, where he actually found the TF MacGuffin he and Sonya had been fantasizing about for so long, and promptly used it to turn his girlfriend into a stuffed animal. It was the sort of dream Derek had on a regular basis, and he was always disappointed to wake up and remember that things like that just don't happen in real life. For some reason, he could've sworn that this particular fantasy felt more real, like it had actually happened just last night. But as he realized that there was no teddy bear in his arms and there was, in fact, a warm body lying right next to him, he was disappointed yet again.
Then he felt the hot breath in his face once more, strong and strangely smelly, and that was enough to prompt Derek to open his eyes. It was dark, but he could tell that the thing lying beside him in his bed was not Sonya, as he had assumed. It was something big, dark, and hairy. He reached over to the lamp on the bedside table and clicked it on, and found that the thing pressing against his side was a grizzly bear!
Jumping out of his bed at once, he was just about to scream at the top of his lungs when the first few rational thoughts and memories started to overtake his instinctual, fight-or-flight response. For one thing, his parents were probably fast asleep downstairs, and as silly as it might seem at a time like this, he didn't want to wake them. Worse than that, he realized that his sudden movement had just woken the giant predator that had somehow gotten into his room from its own slumber. Then, even more importantly, he noticed the collar strung around the bear's thick neck, and everything came flooding back to him.
"Sonya?" he whispered to the animal, noticing the surprisingly human-like look of confusion that had just appeared on its face. "Is that you?"
Sonya, for her part, had missed out on the ending of her change. What with her trying to keep Derek from waking up beside her, she must have dozed off the moment her body became biological enough that she was able to sleep again. Startled by the sudden burst of light shining in her eyes, she tried to respond to Derek's questions, but it came out as a growl. The noise was so deep and so animalistic that it scared her, and then she realized she was the one who made it!
Looking down at herself, she found that the outcome of her transformation was more or less what she had been expecting. She was covered, from head to toe, in a thick coat of solidly brown fur, but that was where the resemblance between her previous form and this new one ended. She was huge, and she felt powerful. The bedroom around her, which had been a sprawling space to her just a moment ago, now seemed like a cramped closet. And Derek, who had been much taller than her when they went to bed, now seemed like a tiny, weak, helpless little thing, especially since he was currently cowering in fear.
Derek could see the bear trying to sit up in his bed, which wobbled like a house of cards under its enormous weight. Suddenly, the wooden frame snapped, sending the middle portion of the mattress and the animal on top of it crashing to the floor with a thankfully muffled crunch. Seeing the damage she had done, Sonya moaned in dismay.
Thinking quickly, and remembering the one aspect of transformation that his girlfriend really didn't like, Derek issued another command. "Sonya, you can talk again!"
"Oh, thank god!" Sonya replied, in a voice so low and husky that it caught both of them off-guard. She stumbled out of the wreckage of Derek's bed and tried to get to her feet. Balancing on her hind legs was a surprisingly tricky feat, considering that she had been doing it for so many years by now. The bears at the zoo made it look so easy, she thought. But she managed to avoid toppling over and crushing her boyfriend, and after a minute she was standing steadily enough. Looking down at Derek now, she could see that he was not so much frightened anymore as he was awestruck.
"How did this happen?" Derek asked. He hadn't grasped just how big Sonya had become, but now she was towering over him. Under any other circumstances, being two feet away from a wild animal with razor-sharp teeth and claws would be utterly terrifying, and he instinctively felt that at least some of that fear. But he knew that Sonya was in the driver's seat of this hulking body that loomed above him, and he trusted that his girlfriend would never do anything to hurt him, at least not intentionally.
"You were talking in your sleep," Sonya replied, with a giggle that ended up sounding more like a deep, rumbling chuckle. "I guess you were dreaming about turning me into a teddy bear, you said the word 'bear' out loud, and well" - she gestured to the collar on her neck with a paw that was frustratingly impossible to point a finger with - "I guess this thing was listening. Sorry about your bed, by the way."
Derek laughed hard at that, breaking the tension that had hung in the air ever since Sonya's unexpected change scared the daylights out of him. They were both starting to actually get comfortable with this. "Oh, that's fine! We have magic now, remember? And magic," he continued, quoting a line he remembered from one of their past roleplays that Sonya had been really proud of, "'has a way of eliminating all your ordinary problems even as it gives you a bunch of new ones.' We can probably just rope the collar around the bed and order it to be fixed, right?"
"It's worth a try," Sonya replied. Then, reassured that he wasn't scared of her anymore, she scooped Derek up into her arms for a very literal bear hug. To think that she was the tiny one nestled in the arms of a much bigger lover just a few minutes ago.
Weakly, Derek sputtered out, "Sonya, I don't think you know your own strength..." Realizing she was holding him too tight, Sonya let go of her boyfriend, letting him drop to the floor.
"Oops," she said. Watching him get back to his feet and dust himself off, Sonya realized she wasn't as remorseful about nearly crushing Derek as she probably should be. Taking something small and helpless, prey, and hurting it felt disturbingly good in this form. There was a devilish glint in her eye as she looked at him this time. "Well, you may be a little too weak for me right now, but we can fix that. Magic, right?"