You consider your options heavily. Applejack's a good girl, mare, whatever. If she wants a foal, why not you to deliver it? She's not married or otherwise taken, so you aren't hurting any feelings. Best of all, she already knows what's going on, so she won't be upset on that level either. She seemed like the best one to start with.

You tap at the row with Applejack and it lit up. The picture of her got a little blush, took off her hat and placed it over her chest as she looked down and away before the entire display vanished in a collection of sparkles.

Celestia gently clopped her clad hooves. "Applejack. She will be quite pleased to have been chosen. She's been waiting some time for the opportunity."

Really? Why didn't she get someone before?

Celestia lifted her shoulders. "We try not to pressure our donors. They just didn't select her, and we weren't trying to force them. You're doing so much for us, at least honoring your decisions seems the right thing to do. We'll have a missive sent to her immediately. You'll perform your duty tomorrow."

Luna stepped up and nuzzled into your exposed side, reminding you that you were still very naked. "Until then, you have free run of the castle, minus a few areas. The guards will gently inform you if you try to go there." You jumped as she licked over your ribs. "Until then, we must ask that you reserve that precious power of yours. You have selected Applejack, so let no other mare distract you, even if they should dare to approach and ask about it."

Other mares knew about it?

Celestia sighed gently. "We have tried to keep it discrete, but due to the... nature of it, we can only do so much. Some do, yes. Nobles especially, so some may approach you, hoping to bypass the selection process. That wouldn't be fair to all the other ponies, so, please, decline them. Be polite, but firm."

Luna nodded. "There are even those that simply find the act... stimulating. Depraved mares." She rolled her eyes. "This is for the life of our species, not mere titillation. Ah, that reminds..." She lifted a hoof and tapped your dangling member. "This won't do. Since you've agreed to stud for us, you need a proper studding tool."

Does that mean any foal you make effectively won't be related to you?

Celestia quickly shook her head. "You will be the father. While we will... gently... modify the script of your body, any foal you beget will be related to you." She smiled gently. "It is fortunate that humanity shares much with ponykind. While the ordering of the script is scrambled, the actual writing is the same." She looked down at your balls. "We will re-arrange them to be compatible, and add a few missing parts. Humanity has no script for horns, wings, or other things."

She can see you looking a bit nervous about it, but her gentle expression didn't falter. "It won't hurt, and we will only be touching those of your seed. All other changes are entirely cosmetic. You will still be you, of this I promise."

"Speaking of..." Luna came up behind you. "Will you be on two legs or four for this first session? Applejack has stated that she is willing to meet her breeder either way and accepts it."

Celestia perked an ear at her sister before returning her focus on you. "You do not have to decide now."

But you were pretty sure. If she's alright with it, let's start on two legs before we go full in. Tripping in the middle of the act would be a bit embarrassing to say the least.

Luna reached around you, her hooves landing on either side of your dangling member and giving it a gentle caress. "Always exposed. You must be nervous..." She was starting to stroke, running the cool metal of her horseshoes along your sensitive flesh. "Now, don't be alarmed. I'm just priming you for tomorrow."

You couldn't see it directly, but you could see the reflections of her magic. Your member grew with every beat of your increasingly excited heart as she played across it. The magic seemed to flow into you and ran right down your center into the filling organ.

It began to swell all the faster. Your vision dimmed a moment as if the sudden influx of blood was too much, but you recovered, slumped back against Luna as she worked.

Celestia smiled gently. "I am afraid I must now inform you that there is no going back. If you had objections to this, this would have been the time to voice any such. You are now an employee and treasured subject of Equestria. May Destiny treat us both kindly."

Her words were worrying in a way, but your eyes were on your cock, still growing. It had long ago reached its fullness, but it wasn't happy there. It grew wider all along, becoming more of a straight pillar of excited male meat as the head became flattened. A ring of flesh swelled up around the middle. Luna helpfully provided, "That is your medial ring. Used carefully, you will use it to excite mares and to help ensure that none of your seed escapes them."

A heavy weight seemed to be pulling you down beyond that. The powerful magic was rushing into your balls and with every thud of your heart they gained a little in diameter as the hair that covered them grew thicker and thicker, forming a pelt that would do well on any pony. That fur spread upwards as your shaft pulled upwards, forming a sheath under Luna's careful watch. You felt incredibly turned on. You wanted to do... something. There were two mares right there.

What about them?

As if Celestia could see the wild look in your eyes, she shook her head gently. "Your masculinity is being focused to be strong enough to accomplish the task ahead of you. Be calm, and this sensation will pass. Remember, Applejack is who you selected."

Luna's magic gripped your member just below where the head used to be and squeezed firmly. "Do not force us to supress your natural urges. Think of something peaceful. I'm almost complete."

You were not... literally hung like a horse. Then again, you weren't as large as a horse in general, and you imagined ponies were much smaller than Celestia or Luna, if the show was at all accurate. The main change was in the structure, though you were pretty sure you had packed an inch or two in there. You felt powerful. You felt virile. You could fuck the world!

A knock caused all three heads, including your own, to snap to a door that led out to the garden you were in.

Celestia held up a hoof. "I'll handle this." She trotted over to the door and it opened under her golden magic. "Yes?"

Whoever it was spoke in deep tones, but you couldn't make out the words.

Luna nudged you forward to stand on your own feet. "Finished. How do you feel?"

You turned to Luna and found that your member didn't jut out at her as it would have normally done. It was angled out and up, mostly up, but not entirely up at least. If one discounted having a horse cock and balls... you felt fine.

Didn't the changes wait until the session?

Luna raised a brow. "The changes to your seed are quite intensive. Better it be done now long before it's needed. Besides, that portion we will not be undoing until and unless you decide to cease being a male once you've been expended."

Speaking of that... Why did he have to be so concentrated in the first place? Humans got each other knocked up just fine without it.

Luna nodded gently. "Though females are fruitful, they were affected by sister's... meddling... Before this, a perfectly normal amount of stallion energy and seed would be quite sufficient to quicken the womb of a mare. Now, much like the moon and sun long ago, it requires so much effort that the user is left without any magic after a time." She sighed, voice heavy with annoyance. "Sister. She thinks she knows the answer for all things. I swear..."

Celestia came back towards you both. "We have to go. You're free to wander the castle, as we said earlier. Don't leave, and obey the guards, and your every need will be gladly met. Thank you, once more."

Luna quirked a little smile. "If you prefer, since you seem a curious soul--" She pointed. "The research area is just that way. Tell them Luna said you could look. Perhaps you will have some fresh ideas. One thing, do not permit them to experiment on you directly. You are reserved."

"That is a royal edict," agreed Celestia. "At the very least, Applejack comes first."

They left together, and there you were, naked and sporting an equine chubby. Your shaft was slowly receding into your new sheath. Having one at all was a bit odd, but there it was. Oh well, you had a full day before Applejack showed up. Maybe it was time to get exploring?

Author's Note

More choices! I tried to incorporate some of the more popular choices selected in the last chapter in the direction and discussion in this one. Having fun? Let me know! Also vote

Choices:

1) Maybe we should cover our shame?
2) Time to mingle with random ponies. Let's find someone that doesn't look like a guard.
3) Maybe a guard is just the pony to talk to.
4) That research area sounds interesting.
5) Hey, hold it. Let's get something to eat and just relax.
6) You're hung like a horse... Maybe a test run wouldn't hurt anything, right?
7) Running away? Never not an option.