(text from the original post):

The above drawing is based on https://danbooru.donmai.us/posts/3523689
(sorry for not posting anything for awhile, I’ve been working on a bunch of different things – but this here is the just the start of a new 20-part, full-length transformation / TG / BE story + breast growth sequence I’ve been tinkering around w/ for a minute, so without further ado…)

Full sequence here: https://www.deviantart.com/horselover-fat-01/gallery/81205791/the-reluctant-rarity

THE RELUCTANT RARITY
Day 1

The Eronomicon.

Its name strikes lust into the hearts of all who know of its secrets.

And now, Raymond’s whole body surged with its eldritch power.

Meticulously, his plan had unfurled – after weeks of Dark Web research, Raymond had sought the ancient book at a sparsely-attended, sparsely-supervised travelling exhibit on early pagan literature that had arrived the State University Library. He had placed his left hand upon its 69th page, and he had recited the occult incantation perfectly as rehearsed. He had shuddered to feel the vortex of secret energy surge upwards from the ragged parchment into his arm, swirling silently within him, flooding his body with the pulsing spirit of The Eronomicon.

His plan was almost complete.

All Raymond now had to do was step into the next room, where he knew Kairi would be sitting down, studying for her chemistry class. It was Friday; he had known she would be there – and he had seen her there just moments ago, just before he had stepped into the Grand Exhibition Hall. He had nursed an obsessive crush on her ever since high school. They had rarely spoke, but Raymond had always admired her from afar, as she had laughed and flirted and dated other men. She was infinitely more popular than he.

But today – at long last – she would be his.

The power Raymond had received was the power to gratify one’s innermost fantasies. With just a single glance, Kairi would begin her transformation into that which Raymond desired most – and yet, since she already met his ideal form to the letter, he knew that it would only be Kairi’s mind which would change… as she surely would begin to fall deeply in love with Raymond and Raymond alone, just like in his dreams… Day by day, Kairi’s thoughts would become more & more obsessive, as her lustful desires mounted… She would begin to fantasize about him, wishing desperately to become his love-slave… Eventually, she’d be begging for his cock… Her mental transformation only ceasing when their desires at last became consummated…

Raymond’s pants felt tight with anticipation.

He licked his lips.

Then, with a rush of cool air, Raymond pushed open the great oak doors which led back to the Study Hall.

He stepped over the threshold.

…

There she was.

There, across the room – radiant as always with her gold, sunny curls, her stylish outfit and that trim, athletic figure – Kairi sat alone, dutifully thumbing her way through a huge textbook at one of the long plywood study tables. She didn’t look up, notice or acknowledge Raymond at all.

According to his Dark Web sources, the first person Raymond laid eyes on would be the one to receive the magic of the encantation swirling within him. Raymond’s gaze fixed upon Kairi immediately as he prepared to feel the rush of invisible energy exit his body to enter hers, supernaturally fusing his own long-hidden desires with her body’s mental & genetic programming… Raymond braced himself…

And then…

Nothing happened.

…?

Raymond was confused.

He focused his gaze on Kairi even harder, still feeling the swirling vortex of magic energy within him.

…

Nothing.

What was going on? Why wasn’t it working…?

Raymond felt a little silly now, staring across the hall at the girl of his dreams, still brimming with a strange energy – and nothing was happening. What was wrong? Was there some final step he’d forgotten? Raymond’s mind raced…

Suddenly, a force like a thousand pins and needles searing into every pore of his flesh swarmed into his system from an unknown source. With an ancient yet oddly familiar sensation, the simmering energy in Raymond’s core fused with this new intrusion like the union of two long-lost lovers, the dark vortex within burbling up in an instant to meet the bright piercing spirit from without. The two merged forces, reunited, dispersed and flowed at once throughout Raymond’s terrified anatomy in a blazing heat of forbidden passion, bending his mind & soul into a gagging swoon, nearly knocking Raymond off his feet.

And then, it was over.

…

What the hell was that?

Massaging his temples and tying to shake it off, Raymond still tingled with a fading, prickly energy that now felt somehow deeply integrated within every cell of his body. His innards trembled with uncertainty.

Looking up front of him, Kairi still hadn’t budged at all, remaining utterly unaware of Raymond’s presence across the room.

Then, Raymond’s eyes darted off to the side.

And…

There, sitting at a remote table against a far wall, Raymond saw a gangly, pale-faced, pasty, awkward, nerdy-looking freshman boy avert his gaze meekly – apparently, the boy had just glanced up briefly to see who had walked in. He wore a dumb-looking shirt with some stupid cartoon on it or something.

Raymond scratched his head, still not really sure what the hell had just happened.

Whatever.

It was getting late. Raymond decided to just cut his losses, go home and get some rest. He was feeling pretty exhausted all of the sudden anyway… He’d probably do some extra research tomorrow to try and get to the bottom of what could’ve gone wrong…

Raymond yawned.

Too self-conscious and afraid to try and say hello to Kairi (who still barely knew he existed anyhow), Raymond quietly sidled out a side-door into a musty concrete relief-staircase that would take him down to the ground floor.

Back in the Study Hall, turning over another page of his homework, the pale boy in the corner coughed.

That night…

The weird tingling sensation in Raymond’s flesh didn’t seem to want to go away. Worse yet, the dull, spinning sensation in his skull had steadily congealed itself into a splitting headache – so bad, his forehead practically felt like it could burst open at any moment.

A grey fever enshrouded Raymond’s senses. His flesh crawled, clammy with icy chills.

It felt… uncanny.

Raymond wrapped himself up in several blankets and crawled onto his apartment couch to get some rest, shivering from an eerie, soft burning and sickly sensation now flourishing throughout his entire system.

Just a cold… or the flu or something…

Laying his head down on a pillow, everything swirled into a hazy swoon.

Overtaken by an all-encompassing, marrow-deep exhaustion, Raymond fell asleep, tossing & turning in uneasy slumber.

…

Raymond’s dreams that night were… bizarre.

In one dream, someone he cared for deeply kept calling out for him in agony, desperate for some form of reunification… but they were locked behind some insurmountable barrier. With each & every mounting, desperate cry of need heard from this lost one, a piece of Raymond’s soul seemed to melt away in sympathetic grief and compassion until soon enough Raymond’s entire dream-body was a warm, indistinct puddle of steaming, fluid mush – finally able to slip in-between the cracks at last, squelching along like a giant viscous amoeba, or something… on a soul-consuming mission to caress & console this missing, desperate, forlorn other-half – no matter what the cost, to give absolutely everything to rescue this dearest one…

This dream was forgotten as soon as it was over.

The next morning, Raymond felt like he’d been hit by a bus.

A disorienting soreness pulsed throughout his entire body, flooding his whole system with a woozy, dehydrated, buzzing anxiety. His inner-ear swirled, making him feel dizzy. His stomach churned – for several agonizing moments, he felt right on the verge of vomiting. And strangely enough, his ass ached – or, more specifically, his lower back: right around his tailbone, which felt hampered by some odd kind of unfamiliar… pressure.

Sitting up, Raymond groaned.

His forehead felt as if it had been split open – a throbbing pain rippled throughout his frontal scalp, His pelvic floor felt sore and kind of itchy, and numb, almost like he’d been kicked hard in the nuts the night before. His right hand reached down to scratch at the offending area.

But what his fingers found… was not what they expected.

Raymond’s hand recoiled.

Then, a digital double-take.

No.

No…!

It was gone.

…

His penis, his balls, everything… it was gone.

All of it.

And, in it’s place…

Soft lips.

Delicate folds.

A deep, senstive gash…

A narrow slit, rimmed with soft, puffy lips, tender to the touch.

…

Raymond had a vagina.

He screamed.

But the scream was not his scream. No 19-year-old male could ever scream like that. The scream was too high, too shrill, too piercing… too female.

…

Raymond was a girl.

But that wasn’t even the worst of it…

Everything in his apartment felt weirdly proportioned… everthing seemed bigger than it should be… or maybe – no… – he was… smaller?

Bolting to his feet, Raymond rushed to the bathroom to assess the full extent of the damage – only to discover that his entire sense of balance was completely shot. Something crucial in his inner-ear had definitely changed, as he struggled to orient himself amidst alien feedback from his diminished frame. Nothing felt right – even the bare soles of his feet seemed awkwardly miniature as they padded quick & unsteady against the beige carpet. Skidding into the linoleum-tiled hallway, a sudden loud crash behind him drew his attention to a smashed table lamp in his wake.

What the…?

Looking back, Raymond was aghast to discover the horrifying source of the ominous weight he’d earlier felt troubling his tailbone…

A tail.

Shimmering violet, coiled into tight, buoyant spirals, sticking out a full 3 feet behind him, bobbing & swaying to the rhythm of his gait…

A fucking tail.

Raymond careened into the restroom and flicked on the light (tail colliding with the doorknob), and there, in the mirror…

Raymond recoiled instinctively, clutching at his chest (distressingly puffier than usual) with one hand and clenching the other tight into a fist – fight or flight –

He gasped.

There in the mirror, a look of terror tinged with disgust on its mutant face, was…. well, it wasn’t exactly human… but…

In most respects, the figure in the mirror resembled your typical 19-year-old girl – maybe just a few inches shorter than average. But her flesh was snow white, unnaturally white… and out of her forehead jutted some alien, bonelike appendage – no… a unicorn horn – and her ears… no mere human had ears like that… and her face – was that a snout? And her big blue eyes… and her glistening purple hair… and that tail…

And…

That thing… it… she… was him.

Raymond screamed.

Next chapter: https://www.deviantart.com/horselover-fat-01/art/THE-RELUCTANT-RARITY-Part-2-C-cup-900871298