"Ally!" Kyle called out sharply. She jerked her head out of the toilet immediately, turning to look at her brother where he stood in the bathroom doorway. Droplets clung to her chin where some soft fuzz had sprouted, and Kyle was further shocked to see that her mouth and nose had pushed out slightly into the beginning of a short muzzle.
Wiping her mouth with the back of her hand, Ally sat back on her knees next to the porcelain bowl. "Sorry bro, did you need some water too?" she asked, making it very apparent that she now thought of drinking from the toilet to be completely normal.
Kyle felt curiosity replace his initial shock, and only stuttered a bit as he responded. "Uhh, n-no, I mean, no, thanks Ally, I had a glass in the kitchen."
"I don't know why you'd get a glass dirty when there's perfectly good water just sitting in here whenever you want it." she said dismissively, getting to her feet and sliding past him to head for the living room. He followed, wondering what another dose of her trigger words would do to her. As she headed for the sofa, looking like she was just going to sit down and watch some TV, Kyle decided to just go for it.
"I guess that's why you're such a Good Girl, sis." Ally seemed to freeze at the mention of those magic words, so Kyle quickly doubled down: "You're not wasteful, like how you use the same food bowl over and over and... and you're such a Good Girl when you go outside to do your business, right?" his sister was slowly moving again, but as he watched, Kyle realized she was sinking down to sit on the floor instead of the couch, her legs seeming to shrink and reform a bit as she came to rest comfortably on her haunches. Her hands came to rest in front of her on the floor; she was sitting just like a dog now, and still seemed to think absolutely nothing of it.
.
"You're right" she nodded, and Kyle noticed something flopping on the side of her head; it seemed her ears had grown out into two furred peaks, folded over and blending with her brown hair. "I don't need a special drinking glass, or a new bowl for every meal. And why would I go pee in perfectly good water only to flush it away? That's some silly human stuff." Her hips and back had reshaped, and as she was talking she raised her hind leg to scratch at the collar of her shirt. Kyle could see that more brown fur was poking out from under the edges of her clothes, and she was struggling to scratch an itch with her shoes still on - he had to help her out a little further.
"A Good Girl wouldn't even wear clothes, I don't think. Right, Ally?" he wasn't sure if her mind was far enough gone to agree with him yet, but based on her body's changes, he didn't think her shoes or clothes would fit much longer. Her t-shirt looked a bit... stuffed, and he realized she was truly turning into a BIG dog like he'd suggested!
She gave him a canine grin as she gazed up at him from the floor. "You're so rrright, Kyle!" she growled, her mouth pushing out further into a squarish-muzzle as she tried to speak. "I don't know wry I even have this stuff on! It's wrrasteful to get them dirrty when I have a perfectly good coat of fur to prrotect me!" She started struggling with her clothes, seeming to have trouble gripping the fabric and bending her arms to shrug off her shirt.
Kyle quickly walked over and bent to help her, pulling the fabric over her changed head and down her arms. As she sat back and shook her head, he got a good look at how much the suggestive hypnotism had truly changed his sister: her breasts had dwindled to flatness while long, luscious brown fur had grown out to cover her torso and was spreading down her arms even as he watched. Something was twitching in the back of her shorts, and as Kyle reached under her hips to released the button and pull down the zipper, a thickly-furred tail squirmed free of it's confines to wag happily.
"Thhrranks, brro." Ally huffed, her long tongue sneaking out to slurp up the side of his face before he could back away. "Hey! Can wre go outside to play? Prrease, Kyle?! Can wre?!" She was prancing in place, her shorts sliding down her completely-canine hind legs to puddle on top of her shoes. Her heels seem to have elongated and risen out of the footwear when she stood to all fours. The only physical reminders of her humanity were her rounded shoulders, human hands and fur-less face - Kyle figured he might as well finish up her changes and take her outside to play like she clearly wanted.
"Okay Ally, yes, we can do that. You're a Good Dog, girl."
She seemed to shiver slightly at the new Trigger Word, and closed her eyes as the final changes took effect. Her nose darkened, and brown fur was finally growing in earnest on her face, spreading to cover her jowls, over her cheeks and up her forehead to meet her hair, which seemed to have parted and migrated to hang mostly from her ears; shorter brown fur covered the top of her head and blended with the rest of her coat. Her fingers were simultaneously shrinking, her shoulders flattening out and restricting her range of motion to that of the dog she now was.
Kyle couldn't quite remember the name of the breed she most closely resembled, but he was amazed to see his sister turned into a huge brown bear of a dog that was panting and wagging it's tail while gazing up at him adoringly. This was some crazy hypnosis!!