A few minutes later, Cindy and Erin arrived at the centaur's house. It was a modern ranch house, which probably cost more than Erin's entire building- the square footage alone was probably more than her Ex's parent's place. Cindy stopped to drop Erin off and went to prepare for a shower. This gave Erin a bunch of time to change things up!
She laid down on the couch, deciding to change herself.
"A human woman is laying on a couch"
Changing "Woman" to "Futanari" led to a small bulge appearing in Erin's pants. Pulling it out revealed a perfectly acceptable human cock and balls. Maybe a bit on the smaller side, but still acceptable.
"Erin holds her human genitalia in her hands."
She thinks back to Cindy, who was currently doing who knows what. Now, even though she originally wasn't intending on getting down and dirty tonight, she did think that screwing Trish's friend was a good recompense.
"Erin holds her equine genitalia in her hands."
The tube of meat in her hands lengthened slightly, but apart from a fuzzy sheath, nothing really changed.
"The dick in her hand is far below average."
Changing below to above makes it grow significantly- from about a pinky finger to a coke can flaccid. The thing was massive, as were the apple sized testicles which were hiding her human vagina. She made her testicles internal and continued to change herself. She figured out that holding a specific body part upped the chances of it becoming targeted. Her flat chest finally bloomed, as did her hips. She also bulked up significantly, although she stayed her small height- she liked the idea of being eye-level with Cindy's chest. Speaking of,
"Cindy is debating on whether or not to cover her c-cup chest."
Erin grinned at this, and changed C to G.
"Erin?" Cindy yelled out from the bathroom, "I'm ready!"
"Coming!" Erin responded, quickly changing "Cindy smells like a horse," into "Cindy smells like a tangerine," to save herself from having to smell horse all the time. She followed the now strong smell of citrus to the centaur, who's large breasts were threatening to explode out of the bikini.
"I- I haven't been swimming since I've Changed." She said, "A-and I didn't want you to be awkward about any of this so..."
Erin gave her a look, to which Cindy paused for a moment. "O-oh right, you wouldn't know. So, you know how there aren't any child centaurs?" she asked, trotting into the ensuite- which was larger than Erin's entire bedroom by itself. It at the other end of the room was a large, slightly elevated plate behind sliding glass. It looked like a bathtub without the sides. In the corner was a console of sorts, which Erin guessed was to control the entire thing. Cindy trotted past the weird looking toilet and opened the door. Her blush deepened significantly as she spun around. "Y-you'll need to strip, though," she stuttered, before pointedly looking away from Erin. The futa stripped, being careful to hide her phone somewhere the centaur wouldn't find it. As she did, the lighting dropped, giving a certain alien flair to the entire room.
"So, Child centaurs?" Erin asked, following Cindy's instructions.
"Oh yeah," Cindy said, "So, I wasn't always a centaur. Neither were Tina nor Trish. We were all humans until we hit puberty, where we started changing. I actually got it the easiest out of us three, if you believe it. At least I don't drip milk everywhere or look like a cartoon character. Although even Trish is rather lucky, considering."
"Why? Isn't making a mess everywhere a bad thing?" Erin asked.
"At least she can still breathe air, and is in mostly full control of herself," Cindy replied. "Spilling milk everywhere is tame compared to some people's experience. Anyways, the Change is mostly unpredictable- two people with no family history of Changed have around a 2% chance of having a Changing child. If two people are changed, however, that still doesn't guarantee it happening- or what the change will be once it happens."
"I see," Erin replied, focusing on cleaning the tauric body. "So, you don't make milk?"
Cindy didn't reply, only covering her breasts. What Erin didn't know was that ever since she had stripped, pheromones had been emanating from her horse cock, all of which were heading straight for Cindy's brain, forcing her into heat. If she had been able to reach, she would have been destroying herself. Luckily, Erin finished cleaning her quickly. She spun around, ready to thank her, only to catch a glance of the now half erect cock resting on Erin's crotch. Green eyes met ambers, and Cindy said one line. "Fuck me. Now."
Erin rushed behind Cindy and lined up with the now lying down centaur's dripping wet pussy. The first pump made Cindy moan, as did the second and third pumps. Equine grilcum was soaking Erin's hips, evidence of multiple orgasms. Her bikini had long since disappeared, snapped off from trying to contain the massive globes hidden behind them. A couple dozen pumps later, and Erin came as well, filling Cindy's fertile womb with pure, virile cum. Her upper body was shaking from bliss, and she finally stopped moaning. Erin waited until her cock softened enough to leave and stopped the shower. Re-aquiring her clothes, she took her phone once more, reading a line off her phone.
"Cindy's virginity was taken by Erin."
Perfect, she thought, before heading out. She did leave her phone number on Cindy's fridge.