The snake paused. Eileen had an idea, and clicked her fingers. Eric's reptilian eyes glittered hungrily as he watched his wife begin to grow.
First, taller. While she had never been small at a respectable 6 feet, Eileen was quickly breaking 7, 8 feet. She stopped just shy of double her previous height at a nice, tall 11'5. Yet even at that size, Eric's head alone dwarfed her entire body. Tight muscle grew across her frame. Thick, solid - though not nearly as powerful as what she'd gifted her husband - she looked like an accomplished athlete in seconds.
But still, Eileen wasn't done. She winked at her partner, and Eric hissed as he found his cocks being pushed apart where they had remained coiled around her thighs. He practically drooled as he saw what his wife had planned. Eileen's body inflated, a thick blanket of fat forming over every inch of her. The muscle still remained, of course, but instead of being lean and hard, Eileen's body had become delectably soft. Her breasts expanded from an E-cup up to a J-cup in seconds. Eric's tongue coiled around her torso and fondled them with great gusto. Her ass became two great boulders of fat, each bigger than her head and somehow even more jiggly than her boobs. Eric quickly found that his huge, long snake cocks no longer reached all the way around her thunderous thighs.
Eileen had filled out in every conceivable sense. Only her tummy stayed taut, a slight hint of abs showing through the smooth flesh, overshadowed by the two beanbags she called her breasts. She was large and gorgeously chubby, thick in all the right places, with curves to die for. Eric couldn't help but constrict himself around her, feeling up her pillowy body.
Eileen giggled. "Oh yeah, honey. And this girl's stretchy enough to take anything inside her," she said. Eric constricted her harder. "But not yet. Got one more improvement for you, my lovely snake."
With a simple thought, Eric's tail began to extend out. Hundreds of feet were added as it grew thinner and thinner, until, eventually, it reached a thickness half the size of a human hair. And with his super strength and impervious nature, he could easily snap someone's neck even with that tiny filament.
But, having a tail that thin did mean he could slip it into his wife's ass and begin stretching it out. Eileen moaned as he did so, feeling him wind dexterously through her intestines, pulling more and more of his tail up into her until she was being stretched by something as thick as a coke can. When he decided she had been teased enough, he quickly retracted himself, and coiled his tail around her body.
Eileen felt her huge body become weightless for a second, as Eric easily lifted her up and positioned her, before bringing her down hard onto his twin cocks. Eileen screamed, but she couldn't fight back as her husband overpowered her and began pumping her up and down, distending her tight stomach more and more with every stroke. One cock up the ass, one in her pussy, Eileen was in heaven. Her eyes rolled back in her head as she took 3 feet of magnificent cock inside her - and she wasn't even hilted!
Meanwhile, Eric controlled every last twitch of his cocks, synchronising the throbbing of their veins with Eileen's own heartbeat. He twitched one of his barbs, letting it rub against her clit with every thrust, even as the tip hammered against her g-spot. Eileen came with a yell, and Eric hadn't even begun yet.
As she was recovering from her first orgasm of many, Eric quickly pressed his snout against her comparatively tiny head. His thick tongue forced its way down her throat, tickling every muscle all the way up until her stomach. And then, he used the super-fine tip of his tail to wind down her ear canal and into her brain. His eyes bore into hers as he began to hypnotise her mid-mindfuck.
His mistress was a squealing, over-stimulated mess in his coils. Her mind was putty. More, he urged her. Give me more!
Eileen was too happy to oblige. She orgasmed again as she found Eric's shafts growing inside her once again, this time without any effect to his overall size. They were simply swelling bigger, and fatter, and longer... quickly surpassing his wife's previous height to 7 feet of girthy, muscular snake dick. He groaned as his body swelled fatter again, more and more muscle piling onto his already titanic frame, and he began slamming his wife down so hard onto his shafts that shockwaves rippled across her flab. A strange sensation overcame him as something changed internally, as well. Behind his testicles, another set of balls were forming, then another. The six of them began to swell until they were visible bumps on his otherwise smooth and lithe form. His refraction period all but disappeared. Pheromones began to leak from between his scales, and his long, black tongue became coated in aphrodisiac saliva as it was massaged by his wife's throat.
Eric hissed and roared as he finally found his limit inside Eileen, where he could feel the indent of both cocks pressing against his tongue where it had wound itself inside her. Eileen herself was incoherent, addled by lust. With a single twitch, Eric willed himself to unload from all six of his testicles, an orgasm of god-like proportions. Eileen expanded like a balloon - true to her word, taking everything he gave her and never spilling a drop of her snake's thick, virile cum.
Gently, Eric retracted himself from his wife and laid her immobile body down on the bed to rest. Then, he manoeuvred his huge body outside the mansion to really stretch his coils out. The miles-long snake hissed as he drew himself up to survey his kingdom - a private island with a mansion large enough for him to coil in every room. He turned to the horizon. He could let loose a little bit before his mistress recovered, couldn't he?