You could feel your pants already starting to strain under the growth flowing through your body. You grin and let out a laugh.
'What is it, baby?' Amy had crawled up onto the table. She had one hand down the front of her pants, fingering.
'I had to be sure.' You look down at your forearm as course brown hair grow outward. It doesn't hurt so much as tingle. 'I asked it to change me into a anthro horse man.' You always had a thing for that.
Amy smiles, 'Awesome babe. I love those.' Whether this was actually true to the real Amy, we can't know. As per his first note, Amy is attracted to you no matter what you are. Even if you were a stool, she would hit that.
It comes over you in waves that lap up against your skin with hurrying effect. You grow taller and wider. Your hips finally are finally too much for your pants as they rip at the seams until you're left with just a tattered bit around your waist and ground. In your head, all that bulging you feel is muscle. Your butt expands to compliment your hips and there is a weight on your chest which, you assume, is from your new pecks. You would have looked down only your face is pushing out.
'I've always wanted this.' You say in a warble. Your voice is changing to match your new body.
Long hairs brush by your new, elongated ears which you can only guess is your mane coming in. You wince at the first bit of pain as your feet cramp and bend over to form your new hooves. Meanwhile your hands mutate into an odd three fingered hoof formation.
'I can't stand it.' Amy bounds down to the floor in front of you. Merrily, she undoes your button and fly then tears away the last bits of pants and shirt from you.
'By all means,' you say, voice a bit higher than you would have thought, 'enjoy me. I'll probably be a little too big for you though but the pen can change that.' As your new long tongue licked your new teeth you already thought of changing Amy into a form more fitting for you. In fact, though your body is still numb and dazed, and still finishing, from the change, you feel a burst of pleasure from your groin as Amy has clearly started her work.
'Could you write something for me dear?' Your voice was definitely more sweet and girly than you would have expected but no matter. You were a man where it mattered, you thought.
Like an obedient dog, Amy pulled from her duties to listen.
'Write that you would like to become the perfect horse compliment to me but with twice the lust you have now.' The last bit was a bit over the top but you figured, why not? The wording was also quite odd but no matter, it would get the job done.
Amy hastily wrote it down and shoved it into the box.
'Now back to your sweet pussy.' What an odd choice of words, you thought. Just before you could finish that thought through logically, your body quivered again with pleasure. You could feel your tail flick, butt tense, and as your new hand rubbed your ample breast, even you couldn't help but be jarred.
You look down and gasp in horror. Instead of a muscled, stallion you are a quite buxom mare. With an ample breast topped with light brown hair, you could see down to your foal bearing hips, and Amy, face deep in your womanly slit.
That wasn't all you noticed about Amy though. As her own shirt began to strain with a growing mass beneath, a tail became to emerge just above her butt.
'Oh no.' You say in your sweet mare voice.