The newly-formed centaur tried her hardest to stifle her moans and remain still. Injuring Tiff would be terrible, even if she deserved it just a little. Katie wanted to at least look behind her to see her friend pleasuring her like this, but that would be acknowledging a few things that weren't so easy to deal with as it was. It was better to just ride this out, she thought as she scrambled to remove her remaining clothes.
"Man, it's roomy in here! I wonder if I could take a nap inside you if I wanted!"
Tiff worked her right arm slowly in and out of Katie's huge pussy, feeling around with her hand as she did so. Her left hand, which had been stroking Katie's thumb-sized clit, soon slipped in to join its mate, and Tiff wasted no time trying to bring her friend to her first climax in this new form.
All the while, Katie was feeling... strange down where her human vagina had been. She swore she could feel herself getting wet down there, but it could've been phantom limb for all she knew. The black-haired centaur's breasts were rather in the way for her to confirm anything visually, though - not to mention she was kneading them out of frustration.
Despite how good it felt to have her arms in Katie's womanhood, it clearly wouldn't be enough to send the girl over. Removing her left arm from the damp passage, Tiff brought the dripping hand back to Katie's clitoris and began to pinch the nub. She felt the movement from that.
Still, that wasn't satisfying enough for Tiff - it was time to get a taste for herself.
The brunette moved her face closer and closer to her friend's opening, taking in the aroma, and began sucking on Katie's clit. Leaking juices from the centauress's pussy trickled onto the area and into Tiff's mouth. It wasn't bitter, as she'd expected from a few tentative tastes of her own juices in the past; it was... like an apple or a cherry or something. This fueled her oral attentions, and she redoubled her efforts.
It was all paying off. Katie, overtaken by these new sensations and the possible retaining of a certain old one, bucked once and stiffened, relief coursing through her. Tiff was almost knocked away from the movement, but stayed firm.
Katie let out a sigh of relief as she released her breasts. Tiff still could be felt on her hindquarters, but Katie was recovering from her orgasm. Out of habit, she moved her hand down to where she was used to having a pussy - after masturbation, it was wise to clean up.
It was surprising when she felt a soaked patch of hair and a faint feeling of a slit.
"Tiff, come around my front! I think I still have my old pussy, too!"
The brunette clambered over to her friend's front. Looking at the junction between human and horse, the fur seemed pretty low-cut, starting only high enough to cover where the vagina would be. Tiff didn't see pictures like these very often, as she was limited to more worksafe pictures where the hairline often went up to the waist.
Then there was the positively wet tousle of fur right where that human vagina would be. Tiff extended two fingers and stroked the area. Katie shivered ever so slightly as her friend found and parted this more familiar set of lower lips. The pussy looked like a normal human female's, Tiff mused. "Not only do you get to be a centaur, but you get to keep both of your pussies? Now I'm jealous!"
Katie finally gathered the courage to speak, grabbing her friend and hugging her. "Don't you dare get transformed before we're done testing me out. I want to at least try to give you a ride. And maybe I'd like to have you take a nap in my snatch."
Tess tried to put on her best pout. "But mo~m, I wanna play with my own body, too!"
This caused Katie to giggle. "You can, sweetie, but only after you finish playing with mine."