No, she couldn't leave things as they were between Menhit and Carmilla. They were adorable and deserved to be together.
The latex demoness wove through her atelier with Zhang slithering close on her heels. Something between saliva and cum spilled out of the lamia's penile-head as she nearly choked on her amused laughter. Erra shared her amusement with puffs of green smoke escaping her filter as she threw open one of her storerooms.
Inspired by the war doll's panoply of deadly internal armaments, the daughter of pestilence had taken it on herself to craft nozzle attachments and surgical tools compatible with her back tentacles. Her favorite accelerated her liquid poisons to a metal cutting jet. Utilitarian at first, but then she had realized the sheer potential they had crafted a few 'fun' additions for herself. Toxin-leaking dildos... vibrating wands... self-lubricating flashlights... although she hadn't forgotten about Menhit. Those toys she and Zheng gathered from the shelves were still prototypes and untested for the doll's anatomy, but Erra was, if anything, confident in her artistry.
Her best friend could butcher humans and demons alike with exhilarating savagery. However, you waged love more subtly than war. "Mhmm," Erra's latex shell squeaked as she pressed a finger against her chin, "Zhang, I'm calling in my favor with the Duke of the Stygian Depths... Think our animal-loving princess would prefer to be reamed with a horse or dragon-headed dildo? You're a better judge than me... Yes, I suppose there is room for both inside her doll body. Anyway, ask him for a week in one of the underwater palaces."
Pestilence's heir and the lamia made casual conversation as they planned out the retreat. Lots of details to decide. A couple of days alone with Menhit while they tried out and refined the toys before Princess Carmilla arrived, and they could have a romantic weekend together. The palaces themselves were like hollow diamond pearls suspended in the depths of an endless sea. Hellish underwater monsters swam outside the resorts, while slaves catered to the demonic occupants every need and desire.
Once back in the atelier, Erra stretched and eased out the creaks in her suit. Her tail coiled behind her and the needle-like tip filled with a viscous blue liquid.
"Zhang." The latex demoness breathed as she circled her assistant, running her fingers up her rows of breasts. The altered human shivered and spluttered more cum-saliva when her mistress flicked and tugged playfully at her erect and milky nipples. Perhaps she'd turn them into cunts or cocks in the future. But she didn't stay there and set her thoughts behind as she continued up her neck. Cupping the sides of her engorged head, Erra coaxed the lamia to lean it against her crotch with a push of her fingers. Between Erra's thick thighs, the latex shifted and opened up in a plush and elastic slit.
There was no need for foreplay, lubricants already dripped from her artificial sex, but Zhang still used her lips to lavish attention against Erra's puffy rubber labia. The demoness moaned as she felt the lamia's earnest and sincere praise vibrate through her empty body with each slithering push of her elongated tongue. They did not love each other. The relationship was that of master and her slave and would never progress further. "Not yet." The plague demon begged between the static groans when she felt her assistant's fleshy glans forcing her legs to spread further apart. Yet, she was a loyal and dutiful slave that Erra treasured.
The rubber woman caressed the lamia's head, feeling her heat and every quivering muscle as she teased the sensitive and supple flesh. Erra returned her fingers to her neck, physically admiring the smooth and flaccid length as it rested against her crotch with her languid strokes ."You'll need something to survive the Stygian Depths." Zhang didn't argue and simply and submissively exposed her neck. Even if she didn't know what follow, she trusted the demoness. The former human bit back the pain she felt when Erra's tail pierced her neck and injected her with the azure solution.
The points of green light in the latex demoness' lenses shone as she took in the woman's changes. Her pussy ached for attention, but her hands were cradling the now coldly shivering Zhang. Layered sections of scales appeared across her body. They were glistening with a layer of faint and translucent mucus that bubbled out of her pores. It soon mixed with her leaking milk and other fluids. Erra envied humans their mutable flesh and she hungrily explored the bulging outgrowths along the sides of the lamia's slender neck. Then the demoness threw back her head and her metallic cry joined with Zhang's lustful and pained scream when the bulges split into sets of thick and ridged gills.
They spasmed as the lamia tried to futility breath using her new organs before she remembered she had a mouth and parted her lips to take deep and shuddering breaths. Such a beautiful chimera she had created. Tucking a lock of stray neon green latex strands behind her mask, Erra reached for her assistant again, her legs spread in an open invitation. "We still have a few tests left to perform." Her latex pussy creaked as Zhang began pressing her lips against her.
She had no bones or organs to worry about, so all she had to do was continue tell Zhang to go deeper. The demoness moaned with sudden relief when the entire cock-shaped head was inside, with the entrance to her sex coiled and elastically stretched around the lamia's neck. The process repeated with each ridged gill. A seemingly endless repetition of strain and relief. Her senses stretched alongside her pussy, and Erra could feel the lamia's tongue and lips wetly kissing the convulsing passage in almost excruciating detail.
"Oh, Satan!" The rubber demoness cried out to her lord as she felt Zhang's neck rolling like a wave inside of her. Ridges and everything pushing and pulling at once. Erra bent over, hands squeezing the lamia's shoulders for support. Her entire latex body was rippling, distorting from the shockwaves of the lashing movements. She wasn't the only one in absolute bliss either. Zhang's cock-tail was twitched against the floor, a puddle of pre-cum already leaking out of the bottom slit.
They continued to thrust building their pleasure together. Their moans and screaming, either muffled or shot through with static, echoing against the domed ceiling and walls. Erra could feel it cresting. Not the only one either as muffled scream reverberated through her. If the gargoyles could complain she knew they would as soon as they saw an entire workstation covered in the sticky yellow-white effluence by Zhang. It was so much, the demoness felt sliver a pride that soon drowned in her own rush of pleasure. Her sex flooded, overwhelming the lamia who tried to retreat. Only made things worse. Or better. Even Erra couldn't be sure as her mind filled with the same interference as her voice.
Another successful test, the demoness crooned as she rested her weak legs against the lamia. She'd write down the notes later.