It’s a nice day in Ponyville. Ponies are trotting about doing their things and everything is in order, but that won’t last long, however.

At Twilight’s castle, Spike was busy cleaning up the place under Twilight’s orders. "Ugh, another day of cleaning. “Cleaning, cleaning, cleaning! That's all she ever asks me to do.” Spike grumbles in annoyance. "All these spell books stacked here without use, she might as well open a library!" He said as he saw a stack of books and began to sweep the dust off. He says as he sweeps, then accidentally hits a shelf, and a book falls to the ground.

Spike sees the book on the ground and looks at it. The cover said, “How to Train Your Pony?” Spike opens the book and begins to read. “First, find a pony, or make your own.” Spike reads. He reads the page with the pony transformation spell, but gets some pronunciations wrong, but it works anyway.

First, he finds his arms feeling numb and he drops the book on the floor, but surprisingly, his feet are not hurt as they are already changing into hooves. Not long after, he feels his backside changing, forcing him to fall on four legs, unable to stand back up on two easily. He starts growing purple fur around his body, forming a nice soft coat. The fins atop his head change into a luscious green mane, like he always wanted. His tail becomes smoother, with the spikes becoming shorter and less distinguished, except for the diamond at his tail, which gained a green color. Finally, a cutie mark of a fireball appeared on his flank, completing his ponification.

"I'm a pony! Wow! Now I can blend in better! Though, I wonder how I can grow wings..." Spike thinks to himself as he notices his fire cutie mark warping and changing. His cutie mark is now a hazmat hazard symbol! His flank changes from fur coat into yellow latex rubber!

"What's this mark?" He comments on his newly formed cutie mark on his yellow flank. His hind legs and tail change, "What's going on? Why am I turning yellow?"

Once the rubber covers his crotch, a throbbing bulge appears on his private area, "Ooh, must touch!" He says as mind starts fading. He touches it as the dronification spreads forward, nearing his neck as he nears nirvana, figuratively.

Spike feels himself panting more and more as his mouth and nozzle gets sealed away by the rubber then gas mask valves audibly pop out of his cheeks. His cheek valves become his main, no, only source of air. On top of his head, his spikes fuse and merge into a black rubber mohawk. Then, he sees his world disappearing as he adjusts to his new visors that formed, having his eyes disappear behind them and his pupils vanishing behind the glass, but he couldn't care less. He keeps rubbing and grinding on his bulge uncontrollably until he suddenly stops.

He hears some ponies giggling outside, and so he goes outside to check out who that was. It’s the CMCs. The CMCs look at him with curiosity. "Are you... Spike?" They ask, seeing him coming out from Twilight’s house, and also partially recognizing him by the shape of his tail, still having the pointed triangle on its end. “Spike, a pony?” asked Apple Bloom.

He moans and pants, seemingly saying yes, leading the CMCs to approach him even closer.

"You're a pony!" said Sweetie Belle. "And with a cutie mark too!” They then look at Spike’s suspicious cutie mark, noting, "I've never seen such a cutie mark before." "Yeah, it's all black!"

Unknowingly, while looking at Spike, he uses his tail and scratches the three CMCs, causing them to get infected too, thus beginning their change into pony drones. "I'm so jealous! I wish I had a cutie mark too!" said the unknowing Scootaloo as yellow latex suddenly appeared on them, and a black cutie mark too. "Woah! The same mark as Spike!"

Oh, I've got one too!" Apple Bloom said.

"Same here!" Sweetie Belle pointed out excitedly.

"Of course it's the same mark, we are all BFFs after all!" Scootaloo exclaimed.

As they were talking, their flanks became yellow latex, with hooves becoming ridged black boots, and suddenly, a bulge grew from their crotches, just like Spike’s! A sense of itchiness suddenly overcomes them from below, as they find their bulge itching. As they touch their bulge, they find themselves slowly losing their consciousness, submitting themselves to pleasure. While they do that, the rubber slowly spreads up and up, showing no signs of retreating or even stopping.

Eventually, they look at each other, filled with lust and horniness. With their uncontrollable desires, they touch each other and enjoy it. With their minds almost completely gone, their heads also go the way of the ponydrone, with their manes changing into mohawks, their eyes changing into glass lenses, and their entire muzzles get sealed with latex. Valves even appeared on each of the CMCs’ cheeks, leaving them only able to pant and moan for air. After that, they were now just horny pony drones, just like Spike.

And Spike, seeing his first task as a pony drone completed, is satisfied and goes off, looking for another victim.

To be continued...

Author's Note

The ponydrone tf process:

The victim's lungs would turn into inflatable air sacs, mainly for carbon dioxide. Their digestive system, once used to make enzymes for digestion, had now become a system used to make latex, and their brains, once just like any other ponies, had turned into a hivemind connector. With their new hivemind, they could not resist doing what it told them to do, even though they still had a part of their old mind.

Before long, their manes would change into black rubber blocks of mohawks, and their tails and hooves turned black as well. Their coats fused with their yellow skin, turning into rubber. The more their minds vanish, the hornier and more lustful they feel.

They would then start to rub/grind/poking bulges on their private areas.