Maybe it isn't necessary to get out of this right away, Erin decided as she hovered effortlessly above the floor, suspended from Trish's rear by a purple fuzzy sheath. Even though they were only walking along the breezeway between Trish's new giant indoor pool and now-larger house, Erin imagined that Trish at a gallop would make being down here feel like she was flying like superman.
As Trish made her way to the bathroom past the new upscale furniture, Erin was exploring the limits of her station. Testing how far back and forward she could reach, she could reach the middle of her knots with her hands but not the bottom of them or their sheath. Reaching forward, she could reach about a foot in front of Trish's forelegs, which Trish noticed her doing.
"What'cha doin' down there?" she asked Erin.
"Just stretching," Erin came up with as an answer. It wasn't really even a fib.
Having found the limits of her arms, she decided to see how flexible her back was. She could bend upward, but not very far thanks to the rainbow barrel in the way. Side to side she felt she was more limber as a cock than as a human, and bending down led her to believe she could bend in half if she wanted to, but she didn't try it because she would have smashed her face into the bathroom floor. Her neck seemed to bend differently too, it was much easier to look straight up, or what used to be straight up but was now horizontal thanks to her prone position.
All this maneuvering around was giving her an electric feeling in her skin, which apparently Trish could also feel.
"Stop that, its time for our first piss together. Remember what the doctor said, crane your neck to seal off your lungs."
Despite her earlier adventurousness, Erin was now feeling second thoughts as she felt the looming pressure was about to be released. She hastily generated a sentence.
"Erin the partial dog-dick is about to experience urination for the first time."
She wasn't used to holding the phone at this angle and fat-fingered her edit. She meant to change the sentence to "...experience love for the first time" but tapped on the wrong word and did not notice. The sentence she accepted instead read, "Erin the partial dog-dick is about to love urination for the first time."
"Ready? Here it comes," Trish warned and released their bladder.
It was too late to edit another sentence as centaur piss started its journey from the bladder above her down the tubes and into her urethra. The sensation was not unlike taking a dick in her pussy. The feeling of rightness of fluid pouring down her urethra was difficult to understate. The way the pressurized fluid stretched her urethra as it flowed from her base, past her knot, into her chest, then finally...
Erin was in the middle of a deep inhale at the sudden pleasurable sensations but found her breath cut short as her neck and head were forced straight. Staring at the bowl of the oversized toilet, yellow piss began to pour past her lips in a stream.
The taste and smell were strong. But something about it changed - Erin found the flavor not repulsive but incredible, like ambrosia from the gods.
It seemed they had a lot of urine backed up, and soon Erin was beyond merely reveling in the sensations inside her and across her nose and tongue. She decided to play with the stream, directing it left and right with her tongue like one would hold their thumb over a garden hose. Trish seemed to notice and scolded her.
"Erin! Don't spray me! Keep it in the toilet!" Trish shifted to counteract the direction Erin diverted the stream, trying to keep it going between her legs. Erin tried to apologize but couldn't get her lungs to work.
As the stream pressure diminished a bit, Erin tensed their bladder–apparently she had shared control over it–pulsing the flow a few times and reveling in the feeling.
Finally after a time that felt long and short, it was over. Only a few drops were left. Erin was infatuated with the feeling of pissing. Why did she even think it would be a bad thing in the first place? She was starting to question why she would even want to separate from this using the app.
With the main event over, Erin's head relaxed from its straight-forward direction and she could finish the inhale she started 30 seconds ago. Despite going that long without breathing, it didn't feel uncomfortable in the slightest. Maybe she didn't need to breathe at all?
A bit of piss was left over in her mouth which she sloshed around with her tongue, trying to extract every last bit of flavor from it. Despite how great it tasted when she was urinating, it now tasted only mildly good.
Opening her mouth to speak let the rest of it leak out onto the porcelain, and she could only sum up the situation as, "wow that was incredible!"
Trish was glad to hear this. It was rough for Erin adjusting to their new shared life. The first day back Erin was thrilled to be a part of filling the pool up with their cum, but then had balked at doing the other thing cocks were meant to do. Trish was trying to be kind by drinking less and holding it in so they had to piss fewer times, but it was simply nature's call. Erin became irate any time they had to go, but it seemed this time was different.
"I'm so glad, you would not believe how worried I was the sensory changes wouldn't kick in. The docs at the clinic said it would be a few days but it's been a week. So what was it like down there?"
"Well, first I could feel the muscles in our bladder release, then I could feel the pressure in my urethra as it traveled up my length. When it got to my mouth, it tasted the same, but it felt like I was drinking the best soda ever," Erin couldn't help but gush about the experience.
"Wow, it sounds like you liked that even more than cumming!"
"Mmm, drink more water."
"Haha I will, now rinse your mouth out, we don't want an infection."
Erin looked around and found a nozzle that pointed up with a handle to open it. Turning it on sprayed enough water she could catch it in her mouth. She rinsed out her mouth a few times before deciding to try swallowing some water.
When she tried to swallow, something else happened. Normally the esophagus contracts in a wave and pulls food down one's throat. This was the opposite. Starting deep inside her, it felt like she was swallowing something backwards as the wave moved up her length just like the urine did a few minutes ago. It seems a few drops were left over in the pipes because she could taste some pops of flavor as they were expelled from her urethra.
Apparently Trish could also feel this because she said, "good, I didn't have to remind you to do that this time."
Feeling like she had sufficiently washed all the urine out, Erin shut off the water. "Alright, I'm done!"
"Ok good, I'm ready to go to bed", Trish said while yawning. Erin was starting to feel tired too. It was hard to believe things unfolded so fast. She only started using the app at 9:30.
As Trish was cleaning up for the night and Erin was slowly being pulled back into their sheath, she got to reflect on what had transpired
In the span of the last few hours, Erin turned three people into centaurs, one of them giant with udders to match. She had given herself a huge horsecock which she fucked one of them with, then got fucked by another. With two bad sentences she got stuck to Trish's dick then merged with it. Maybe those sentences weren't all bad? She did love urinating–just like the app said–so maybe the changes weren't bad at all.
As Trish settled them onto the bed and Erin's arms were nearly at the lip of the sheath, she noticed Erin still had her phone.
"Here, hand me that and I'll plug it in," Trish offered and held out her hand.
Erin looked at the phone and saw it had adequate charge for the night.
"No thanks, I'm good," Erin refused.
"Alright, well don't loose it in there," Trish relented.
Erin's shoulders were now inside the sheath so she tucked her arms in and let herself be consumed the rest of the way.
Snug inside, Erin fell asleep quickly, dreaming of what would happen next.