"Well, I've always wanted to be a centaur," you reply. "They're so strong and majestic... I would love to be one for a while."
Jamie smiled. "I knew you'll choose that! See, I've even marked the page..." He turned the book, and you could see a little red mark on the page. You smile. "You know me too well, dude."
"I sure do! Before changing, I would like to tell you the exact details. You see, this isn't Disney magic, and this process could turn badly if we're not specific. You'll be a centaur for the rest of the vacation. Don't worry, your parents won't notice you're missing-that's the coolest part! Everyone-exept for me and you-will think that you being a centaur is completely normal. Your parents and other friends will remeber you as my brother, who was changed due to a badly-casted spell. Isn't it just awesome?"
"Whoa," You reply. "Are you serious? That's amazing! I'll have nothing to worry about!"
"Exactly! And since you were ever been a centaur, your belongings-clothes, food, etc. will also change to accommodate this. The spell won't effect us, so even though everyone will think nothing has changed, you will have to adapt-well, both of us will. We'll need to train together, and try to act natural about everything. Understood?"
"Yeah, but if it's a task for you, why wouldn't your parents be aware as well?"
"That's the whole point! That's what they're testing..."
"Cool," You reply. "Anything else?"
Jamie giggled. "You're so eager, are you? No, we can start... but, and I'm sorry for your incovinience, you must know two things... well, actually, three. First: you can't go back. Since the transformation will start, you'll stay like that for the whole month. Secondly, the transformation won't be painful, but it could feel very strange. And lastly... you'll have to transform naked. As soon as you'll finish changing, you'll wear you new-reality clothes, but during the transformation, you can't wear anything, it negates the magic." He explained.
"Fine," You sighed, and stripped down.
"Oh, not here! You'll be too big for this room... or not, actually. The room will probably also change... but let's not risk it. Come outside."
You followed Jamie outside. He standed near a circle of glowing runes, and you backed of, nervous.
"Don't be afaraid, nothing bad will happen to you. Just get in the circle, and I'll cast the spell."
You entered the circle, and Jamie started reading words in a strange language. Suddenly, a wave of yellow energy surged from Jamie's hands, and struck you in the chest, making you fall over.
You raised up, and saw Jamie looking worried at you from outside the circle. "Are you alright?"
"Yeah, it was mostly suprising." You said. You looked at him, feeling exposed. "Is it going to start already? I don't like standing here all naked."
"It already has started," Laughed Jamie, and pointed at your butt. You didn't understand. What was he talking about?
Then you felt a pushing sensetion right above your anus. You looked back, and saw a slick, black horse tail coming out of your body. It lengthened, and a starnge feeling filled your mind, making you wonder what was that. Jamie called: "See if you can control it!"
You focused, and realised what was the strange feeling in your mind: You could control your tail now! You swished it, and laughed in amazment. Having a tail is so cool!
Your foot felt warm. You lifted it up, and watched in horror as your fingers mashed together and started turning black. "What is happening to my foot?!" You shouted.
"Relax, man, you're getting your hooves!"
How could you forgot! Horses have hooves, and no fingers!
Your foot became more round, and the same happened to your other foot, completeing their changes into horse's hooves.
Next were your legs. They shifted and lengthened, and changed their posture, becoming equine. You felt a bit unbalanced-no wonder horses walk on all fours, walking on two hooves was so hard!
Your lower part started to extand, becoming bigger and bigger, sprouting fur and gaining mass.
"I think it's becoming your horse body... oh!" Said Jamie, and you screamed, as a new pair of horse legs sprouted from your abadomen, and your lower part became a full horse's body. You were standing on all fours now, your lower part mostly equine. It continued to sprout fur and get bigger, and you sighed in relief as you became more balanced.
A wave of heat passed through your privates, and you could feel them changing, getting bigger, and covering in fur. You tried to look at your part, struggling to bend your back so low, and saw a sheath covering it, finishing your transformation. The runes faded, and the circle disappeared. Jamie walked up to you, and stroked your back. "You look so cool, man! Come, we'll get you a mirror so you can see yourself."
You started walking after him, but immideatly fell over. Jamie laughed. "Oh, right, I guess you need to learn how to walk properly... as a horse, I mean."
You blushed. "Yeah, guess so..."
"It says here that you should walk with left hind, left front, right hind, right front, and repeat. Try it," Suggested Jamie, looking at his phone.
You tried it, and it worked! You started walking, and then decided to run! You ran-no, trotted-in circles, feeling fast and strong. Who knew that running could be so great?
Jamie couldn't stop his laughter. "Geez, dude, it looks so funny," He laughed. You turned to him, and asked: "What will we do now?"
"Well, first we'll get you a mirror. But then... I don't know, what do you want to do?"