"It could be anything, really," Droze answered. "Most often a close family member like a parent or sibling. Age has a lot to do with it, too. If you're old enough, you might become my new parent."
"Just age? What about gender?"
Droze tilted his head in thought. "I'm not sure. I don't think that matters at all."
By now, the blue scales had covered you from head to toe, thick and armored like a crocodile in some places, tiny and silky smooth in others like the underbelly of a lizard. Suddenly, an unseen force shoved you down onto all fours right before your shoulders and hips seemed to fold inwards, becoming those of a quadruped. At the same time, your body took on a more streamlined shape, even shrinking a bit to leave you about the size and shape of a greyhound. While larger than Droze by a fair amount, you were nowhere near the horse size of those three from earlier.
"Just great," you growled, your voice taking on an oddly musical sound. From what you had heard so far, dragon voices were close enough to humans, though they could switch to more bestial roars when it suited them. Still, did the other dragons sound so high and soft? "So, why am I so small?" You asked as you shook off your now ill-fitting clothes.
"I guess you're still young." Droze inspected your shimmering blue form that steadily grew longer thanks to your lengthening neck and developing tail. "I'd say you're older than me, but only by a little. Oh well, I was hoping for a new mother, but a big sister will do just fine. At least, I won't be alone anymore."
"Sister!?" You bent your swan-like neck to glance between your hind legs in time to see the last hint of male genitals vanishing, leaving nothing more than a slit barely visible amongst your scales. "Ah! No, not that! Not Tha-aaaARAWRR!" Unfortunately, your face had chosen this moment to elongate into a reptilian muzzle, the last of your human features melting into those of a perfect little dragoness. Your physical transformation had completed.
Your first surprised roar faded into an odd calm, and you felt new instincts and thought patterns entering your mind. A certain familiarity with your new shape settled into place until you no longer felt as out of home in your new skin, or your new gender. "T-This is me, now," you breathed. "I'm a dragoness." You looked at Droze with sudden affection. "I'm your sister. I love you, and I'll always take care of you."
Droze let out a cry of happiness and leapt onto you, nuzzling into your warm side as you wrapped your serpentine tail, now as long as the rest of you combined, around him in protection. You were not about to let anything hurt your little brother ever again.