So many fine choices. You felt torn between them, but one rose to the top for you. Starlight. Maybe she'd have answers, or at least be worth talking with, and, by default, you had to speak to her before you got 'to business'. You reached out and touched her line.

Starlight's icon smiled at you. It wasn't the demure little blush Applejack had given, but one of a confident alpha sizing up her prey. "You'd better be worth it," spoke the icon before the whole thing vanished in sparkles.

Seriously, was that Celestia's doing?

She shook her head. "Every mare was allowed to have a reaction of up to two seconds in length in the event of selection. I'll have her informed and brought to Canterlot. For now, you're off duty. Even if you two hit it off, I'll be giving you some time to recover. The first time is the most trying time." She turned for the door of your suite. "For now, I leave you to rest."

Celestia strode free of the room on elegant hooves and was soon gone.

Shoot! You had more questions for her.

You were also tired. So tired... You flopped onto your bed and everything went black. When you awoke, you were under the blankets instead of on top of them. The room had been cleaned and freshened and a small tray of food was waiting for you. You were being watched, though not by uncaring sorts. A mixed blessing at best.

You slid from bed and took care of biological imperatives before grabbing the pants you secured from the lab. A soft knocking came just as you were about to get some food. You called out for who it was.

"Tailor," came the female reply. "I'm here to fit you. May I come in?"

Oh yeah. That'd be good instead of the baggy stuff you were wearing. You grabbed a roll and chewed on it on the way to the door. You threw it open to see one of the mares from the list.

Sassy Saddles smiled at you. She was shorter than you, but not by much at all. She was almost as tall as Celestia. Almost. "Hello! I hope I didn't interrupt anything." Her eyes glanced left and right. "When I received word the stud needed a new ensemble, I just had to lend a hoof. Rarity would never forgive me if I didn't." She stepped inside without being directly invited, but you didn't get any hostile vibe from her, just an eagerness. "Now you just stand there and I'll have you measured in no time at all."

You gently assured her there wasn't any huge rush. Besides, it was a chance to speak to a pony from outside the castle walls, so you asked her how things were going in Canterlot.

Her magic was holding a measuring tape that she held out to your shoulder to your fingers and then hips to legs and again from your groin to your legs on the inside. "Oh, ponies are trying to keep a stiff upper lip about it." Her magic gently nudged your large balls. "Were you... You are a large one." She raised a brow a bit as she moved on you measuring your torso length and diameter. "I heard the studs are just... made for this." She leaned in. "Is it true?"

You weren't sure if it was a good thing or not that Sassy was as curious about you as you were about Canterlot. You assured her that you were born for living, just like anyone else. You were custom adjusted for the current crisis, however.

Sassy nodded softly. "Then it's a very good thing you're doing." She tilted her head before circling around you. "I volunteered my name to that 'mare registry' of theirs. Did you see me?"

You had, and said as much.

"There must be so many... I suppose I can't blame you for picking somepony else." She sat on her haunches and tapped a chin with a hoof. "Do you have a preferred style?"

Something casual, comfortable, and easy to move in. Yep, that's all you really wanted.

"Casual, comfortable, easy to move..." Sassy nodded as if engraving each requirement in her head. "I've made some clothes for a stud before, though he was far less... mannered than you. It will be a pleasure to clothe you." She leaned in again. "Might I pry who you did select? You don't have to, I'm just curious."

You weren't sure how kosher that'd be, just giving out other pony's information like that. You gently turned down that request.

Though she pouted faintly, she didn't seem bitter. "I hope it goes well." She stood up. "For now, I have a few outfits to make! I'll bring them here, and you can take the ones you like, tell me why you don't like the others. I'll adjust them until you have a full wardrobe you not only can wear, but love wearing!" She bubbled with industrious eagerness and began to trot to the door. "Ta Ta, Stud. Have a nice day!"

With her gone, you eagerly devoured the breakfast provided. Was that bacon? It tasted a bit like bacon, huh...

Sleep had, breakfast eaten, a new day begun... Yep, you felt ready. Your muscles were a bit lethargic, but entirely functional. You saw no reason to literally lay in bed all day. You threw open the blinds to allow in all the sun, filling the room with bright light, and a distant view of Canterlot far below.

It was a pretty place. Hopefully you could help, somehow, and keep it that way.

A clopping came from the door. Who could that be? You shouted to ask the question.

"It's me," came Careful Study's voice.

You told them it was alright to come in, and they did.

She approached with an unsure smile. "I was told your first session was a rousing success. Applejack is confirmed to have taken and is being monitored closely in the castle for a few days before they let her go home." She looked you over, from your naked chest to your clothed bottoms. "I... think we..."

Why wasn't she on the list?

Careful jumped at that. "I wasn't?"

She didn't know?

Careful frowned a moment before it cleared. "They probably took me off because... They know what I did." She sat down, looking upset.

You reminded her they still let her just walk in. They didn't have any objection to them talking.

Careful blinked at that. "That's a good point. Still, why wouldn't they let you pick me?" She seemed to realize what she had just said and went a fierce red. "I mean, if you wanted to!"

You promised it was alright and gave her a soft pat on the head that she seemed to enjoy. By the way, you did have a question for her.

"Yes?" She perked up and smiled. "How can I help?"

You decided to be straight forward about it and told her your theory about her being a former stud.

That blush turned to a pale texture quickly. It wasn't an answer, and yet it was. She looked terrified.

You pick up her stunned body, though your muscles protest being used. She was lighter than Applejack at least. You set her down on the bed gently as you spoke in a reassuring voice, telling her that it was alright. You just wanted to know the truth.

"No wonder they took me off the list." She glanced away. "I... Luna tried seeking out friendlier studs. She tried to find a male that had great empathy for females, and she found me. I am a female, I just had the wrong body..." She sat up a little. "So there they were, asking me to be a male, just for a little while. Be their male well enough, they promised, and I could become the woman I always wanted to be. No surgery, no fakeness, all woman, even able to give birth. I... took the deal."

Careful Study was a transsexual that hadn't gone for surgery or hormones. Well, she had been. She had become a mare, entirely a mare. You asked her if she was happy.

"Beyond... anything." Her ears lowered, looking embarrassed. "I mean, sure, it isn't a human female, but female. And it's real. Human doctors, what can they do? Hollow out pieces of you and flip it inside out in a mockery." She cringed with obvious terror at the idea of modern sexual reassignment. "I've heard... from other trans that they don't even try that hard to even make it look right, and it isn't right. I..." She trailed off slowly. "It was... Why am I even talking about that... You must be disgusted." She looked up at you, shrunk with worry.

Of all the things you'd seen so far in Equestria, a trans pony that could just be a mare with magic seemed so distant from the top of the list. You sat down beside her to be closer to her level and put an arm around her. You pulled her in quietly, and she flopped against you. She began to sniffle a little, shedding almost-silent tears.

When the emotions had passed, she sat up against you and suddenly hopped up. Her hooves on your shoulders, she gave you a kiss on the lips but only for an instant before she hopped down to the floor. "You're a real gem." She glanced left and right. "I almost forgot why I came here in the first place! We need to do some measurements, see how your body and aetheric network are responding to the shock of your first breeding. Take off those pants and we'll get to it."

You obliged her and were soon laying on your back on the bed. She hopped up between your legs with a curious-looking caliper floating beside her. "Wider." She nudged a leg with a hoof. You spread your legs a bit wider for her and she slid the calipers over your balls carefully. It began to blink and glow in different patterns and it tingled just a little.

"Lower than where you were when you first visited me," she reported. "But well within acceptable levels. I'll be taking this measurement daily. Eat well, get some movement. With luck, we'll coax you up to full again." Her smile was hopefully, but clearly a little overly-optimistic.

You asked her what the odds of that were.

She cringed faintly. "We had one stud that recovered completely the first time, then began to degrade. Most degrade immediately and fall lower and lower until..." She pulled the calipers back carefully. "Gone."

About that, just how many times are we talking? A dozen? Six? Four?

She slipped the tool away into some pocket she somehow had in her fur. "It depends on the stud and how they treat themselves in part. Be healthy and active and happy." She smiled. "You do have friends. You're not alone."

That was all very good, but a startling lack of an answer.

Her ears flipped back. "It can be anywhere from three in one case to thirty in the longest case. S-Still! Please, stay optimistic. I think that's an important part. Feeling isolated and depressed will suppress you even without breeding going on. So many of the other studs were so isolated..."

How many times had she lasted?

She went red. "I... made six foals."

Did she ever talk to them, or their mothers?

Careful squirmed in place. "Just one... We're dear friends. The others... they didn't really want to talk to me after the fact." She turned for the door. "I should let you enjoy your day. You know where to find me. Come any time you'd like."

Author's Note

https://www.surveymonkey.com/results/SM-28HDHZBN/

Many mares were thought of, but Starlight... Her demanding gaze was quite insistent. This was a mare that had answers, perhaps...

Well, a day off! What do?

1) Let's make friendly with some random ponies in the castle
2) Forget the ponies, it's the castle I want to explore
3) Back to the research area.
4) Can humans learn magic? Let's find out!
5) Join the guards for a real workout
6) This day is for chillaxing. Engage full relaxation
7) Ask permission to visit Canterlot
8) Forget that, sneak out!