Joy seemed to return to the dual-toned slime girl's face and she began excitedly humping against Fey while quickly jerking Astrid up and down on her length at the same time, the tentacles that had been tending to Ellaria and Flora and Lily doubled in pace and even more tentacles began to rise up from the slime puddle.
Faster and faster the slime girl bounced atop the centaur, each bounce producing a happy short "SQUEE!" from her mouth. Her massive pussy which covered most of Fey's hips slapping down with a wet schmack against Fey's stomach each time she hilted herself on the centaur, her tentacle pussy furiously wriggling and vibrating against Fey's length, activating every nerve cluster that Fey had and even some she wasn't aware of.
Fey groaned as she was pounded, and then that groan rose into a rising shriek as she started to peak. The slime girl seemed to understand this was the moment and redoubled her bouncing, her pussy tentacles going mad in their writhing.
Astrid cried out as her belly bulge pushed her breasts apart, the massive penetration slipping up and down her abdomen as she was rapidly slammed up and down her abused cunt made to take it all, schlpop-pop-popping over every ridge and nodule of the dick's length, her insides stirred and stimulated like nothing she had ever felt before. She whipped her head back and howled as a long squirt sprayed from her pussy and hosed clear fluid up the slime girl's stomach and up the underside of her enormous breasts, back spattering onto Astrid's face.
"AAAAAAAAAAAAAIIIIIIEEEEEEEEEE!!!"
As Astrid climaxed the slime girl slammed her down to the base of her dick, slapping her thighs up against herself as she hilted to the limit, entirely encasing her semi-transparent length inside the minotaur. At the same time she came down on top of Fey so hard that it nearly hurt, her massive swollen pussy squishing flat as she collided with Fey, her enormous melon sized clit slapping down on Fey's horse stomach as her pussy went wild. Clear fluid exploded from her puss as the slime girl came, and since she was so vast, she came in staggering amounts. Fey choked as clear fluid hit her like a wall and her upper body was entirely covered in a river of fem fluid to the point that she couldn't breathe, asphyxiating as the waterfall just kept coming, more and more as the slime girl shuddered and wobbled atop her, her slime body wobbling alarmingly.
Astrid wailed all the louder as the slime girl started to cum, the same transparent fluid waterfalling from her puss spraying up into the minotaur's womb, bulging her belly out until she looked pregnant with triplets.
Fey tried to cry out her self but succeeded in only getting a throat full of the slime girl's fluids, the best she could do was groan and splutter as her hips started violently bucking up into the giant pussy until her whole body stiffened and both her spines arched as her eyes rolled up.
Fey exploded into the slime girl, instantly filling her pussy to capacity with piping hot horse cum and then surging upward, the hosing cum visible through the slime girl's body as it punched upward and rapidly bloomed as it filled her out.
The slime girl opened her mouth and shrieked, her entire body shuddering and quaking as she was forcibly injected with Fey's impossibly virile cum.
The slime girl's stomach rapidly swelled, a great orb of horse cum growing within her 'womb' billowing outward, swelling her tummy, making her look three months pregnant, then six then nine and with triplets, then octuplets, it just didn't stop and Astrid was pushed down as the cummy mass in the slime girl's tummy ballooned in front of her.
Fey came and came and came, the unique stimulation of the slime girl's pussy dragging from her an incredible ejaculation, a lake's worth of cum inflating the slime girl massively, causing her to keel over with the weight of her own belly, touching down on the puddle below. Her head was thrown back her mouth open wide, a silent scream ripping from the slime girl's lips as her eyes rolled up and she came even harder, her whole body vibrating and shuddering her tentacles plunge fucking the other girls, going into arhythmic spasms, ripping crackling squirting chain orgasms from them in their brutal motions.
Then the slime girl's body began to glow, rapidly brightening to a blinding brilliance that could not be seen through.
The cacophony of squealing orgasming creaming cumming girls peaked as the brightness took over everything, and then only the sound of moving shuffling slime could be heard.
At last the light died and Fey found herself lying in a puddle of clear fluid. She lifted her head, her hair plastered to her face from the slime girl's juices. She carefully pushed away the hair from her eyes and looked around.
The band lay slumped around her, near comatose from being so utterly ruined by tentacles, their pussies gaped in the open air.
She blinked as she caught sight of something. It was a wall of white amongst the pillars. She blinked blearily as she tried to understand just what she was looking at. It was like a massive white tube. Furrowing her brow she looked around and found a second white tube on her opposite side too. Then her eyes slid along their length and came to a stop by some sort of vast glossy white cave the size of a small room. The cave's walls were moving and their surface was covered in thousands of wiggling white tentacles. As she watched the walls moved, shifting and clenching as fluids oozed down from the ceiling in long stringy lines.
"T-tentacles on the inside…?" What she was looking at slowly dawned on Fey. It was the vast, mind bogglingy huge, gaped pussy of a slime girl, far larger than its previous incarnation, and the two vast tubes to either side? They were the mind breakingly large thighs of said slime girl. The entire band was currently lying between the slime girl's thighs, her body surrounding them.
"Oh fuck."
She swallowed nervously. Just one wrong move and the slime girl could bring down the entire structure on them, those pillars would only stand up to so much and a very large slime girl accidentally snapping a few could only mean bad things. The slime girl had truly evolved beyond anything she could even comprehend.
"W-Wummy? A-are you there? Please don't move, you'll break things!"
She listened and thought she heard a very distant and muffled "Squee!" from far away. It seemed the newly evolved slime girl understood something of her situation at least. She looked around at the others but they were still passed out on the floor, occasionally twitching from the aftershocks.
"Just what am I supposed to do about this?" she muttered.
The slime seemed to respond to her words and as she watched it began to soften, shapes blurring, becoming more rounded and slime like. The slime then seemed to pull in on itself and the vast quantities of mass dragged toward a central core, legs and torso rolling inward, becoming one big rounded blob. She stared as two big dots appeared on the giant slime monster and she realised she was looking at Wummy's eyes. This new Wummy was significantly larger than even the blue slime had been.
The slime monster looked down at her, and Fey felt not a little concern for her current situation. Tame or not, Wummy was still a slime monster, a dangerous and powerful one that had just somehow absorbed and subsumed another dangerous and powerful slime monster making it, (Her now?) even more dangerous and powerful. She shifted her hooves nervously.
"Squee?" said Wummy, its roundness tilting questioningly.
"You… you haven't seen Vivi by any, uhm, chance?"
The slime stared at her making Fey all the more uncomfortable. Then she once more began to shrink down, this time however Fey had the distinct impression this was different. The amount of mass was not being compressed and shifted just a little but a whole heck of a lot. Wummy shrunk as she watched, going from a terrifying more than two stories tall to half then a quarter then smaller still. It occurred to Fey that the slime tentacles that the slime produced did not in fact come out of nowhere but were in fact compressed mass in the slime's normal body that was allowed to expand, and when she retracted a tentacle that mass was simply compressed once more. What the slime was doing now was simply a greater, more intense version of that, compressing down her vast mass into a much smaller denser package.
The slime was slowing now and she seemed to struggle somewhat to compress herself, crushing herself down smaller and smaller until she seemed to hit a limiter. The slime stopped at about twice her original size. The only real difference apart from that was that her transparency was slightly more opaque.
As Wummy shrank Vivi was revealed lying on the ground behind her. A single tentacle slipped from the slime and dragged the vulpine close, then touched up against Vivi's exposed pussy, fondly petting her muff, then running the tip along her slit.
Before the slime slipped inside however it turned and looked up at Fey.
Then she spoke.
"Squeecret?"
Fey near jumped out of her skin in surprise.
"You can speak? Oh, oh gods, what have I helped create? Wait, wait, did you say secret?"
The slime nodded, or rather rocked on the spot.
Fey opened her mouth, looked around at her passed out band, then slowly closed her mouth.
"I told Lily and Kayla off about this, I can't…"
The slime looked at her, seemed to shrug, then slipped inside of Vivi, the vulpine let out a whimpering moan in her sleep as the increased mass of the slime monster squeezed up inside of her, her belly filling out massively more with Wummy's increased size making her look pregnant with octuplets.
Wummy had returned home.