Before I could even close the door on Jesse he had me, a flick of his wrist was all it took to freeze my body in place. He beckoned me in with a finger, and my body obeyed by closing the door behind me.
I could feel more magic in me even as he released my body. My clothing, ill-fitting male's uniform, was quickly changing into some skimpy little girl's uniform. The skirt barely made it down passed the panties that cupped at my sensitive areas. I had to nicker in pleasure, which made me blush furiously. I didn't even know if the blush showed under all that cheek fur. Jesse stood up, and I actually felt smaller in his presence. That, or he had just made himself bigger since we last saw each other. The tall stallion cast a long shadow over me. It intimidated me just long enough for him to grab me by the wrist and fling me onto my own bed.
I could smell everything now, and on my own sheets I smelled my human, male self. But mixing with that was something new, the smell of barnyard lust, plush fur...but more than anything the musk of this massive stallion filled my nose. He lifted my skirt and tugged down on my panties before pressing a thumb right into my tailhole. I squirmed around in his grip, but it useless. Soon I figured out what he was doing, he pressed something cold and around against my pucker. I looked back to see a vial of some bubbling potion sink down into my body. The warm rush of fluids was so...sensual in this body. My thick nipples pressed bra-lessly against my shirt, even inch of them showing, and my tunnel flushed with fluids. The deluge made my moan and squirm more, the panties were still hugging against my pussy and seemed to catch most of the juices. I howled, snorted, and neighed like a horny little filly, my hooves and legs struggled against my sheets.
Jesse's big hand came down and smacked on my ass. Hard. I screamed from the sensation, a powerful mix of pain and pleasure. But the feelings afterwards were so much worse. "You know how this works right?" he said as a rumble came up from my belly.
"Wh-what do you mean?" was all my girlish little voice could squeak out.
"An orgasm is a sign of acceptance to these spells. For every orgasm you have, you'll spend another day like this. Oh...and they compound, so watch out for those multiples, little filly."
I actually felt my ears droop as he said that.
"I, for one, am looking forward to spending the school year as a big, buff stallion with a huge dick. Hope you enjoy being my fuck-mare on the side. Oh yeah, did you figure out what that potion was yet?"
I really hadn't, not until it happened... My stomach was rumbling so badly now that I couldn't stand it, the pressure only had one place to go.
"Oh god!" I shouted as my ass fluttered in a loud fart, then another. Each time my round rump seemed to expand, like a balloon that grew every time it let out gas. I was sobbing by the time the third fart came out, my now massive ass sticking up in the air and straining those tiny little panties. I was shocked to find my breasts doing the same, each fart made them bigger as well, my nipples ached as they started to leak milk out. "Nnnngh! Y-you made me into a fucking cow!" I screamed, though in my lusty mare's voice I'm sure it didn't sound threatening at all.
He chuckled at me.
"Oh you'll be my little brood-mare, don't worry. But I'll let you stay a horse as long as you milk yourself dry every day. As for the farting...anal, twice a day at least. That will keep it down, and shrink you back to your sexy self."
Just then I let out another frrrrrt! sound, my panties snapped when my butt, thighs, and hips all grew out at the same time. I looked down to see my fat breasts and thick thighs wrestling against each other. "Nnnngh! Please, I'll do anything to this stoooop!" I stressed the last word hard as another loud fart droned out, my fattening ass gave my just enough pleasure to make me squirt out my first female orgasm...before passing out in a puddle of sex juices and mare's milk.